Almost
nobody seems to report the positive side of our recent climate change
action. It’s remarkable what we’ve done in two years, which gives us
much hope that we can indeed rise to the challenge. I have never in my
life seen such a coming together of nations worldwide to solve a
problem.
And the young particularly are driving action, as in Greta Thunberg’s emotional speech to EU leaders.
Longer video here
However
there is much understandable fear, and even hysteria, in some
responses, which doesn’t seem to be strongly based on science. As an
example, the Extinction Rebellion are disrupting services throughout
London right now, with the aim to get the UK government to commit to
zero carbon emissions by 2025.
Government must act now to halt biodiversity loss and reduce greenhouse gas emissions to net zero by 2025.
Our Demands - Extinction Rebellion
I
can’t find where they derive that figure. It isn’t in the 2018 IPCC
report which says we need to reach that level by 2050 for the 1.5 °C
goal.
I
do support the need for urgent action. But I also come across a great
deal of fake and exaggerated news on climate change, and help people who
have got scared by the junk science into a sense of panic and despair.
There’s
a pervasive idea in our society of an almost impossible situation, that
we can’t do anything about climate change, or that nobody is doing
anything, or that we are headed for a doomsday scenario and it is almost
over, already. None of that is true, not remotely so.
I’d
like to focus in this article on what the climate scientists themselves
say. Also on what we are already doing, and what they say we need to do
in the future.
The EU reduced emissions by 22% from 1994 to 2017. It is on track to meet its 2020 target
- 20% cut in greenhouse gas emissions (from 1990 levels)
- 20% of EU energy from renewables
- 20% improvement in energy efficiency
Progress made in cutting emissions - Climate Action - European Commission
It’s long term strategy is zero emissions by 2050, and if it achieves that, it makes it 1.5 °C compatible. The UK has done even better, a 40% reduction:
See Slow burn? The long road to a zero-emissions UK. In the UK, our emissions are now the lowest since 1920.
China
and India are often criticized because their emissions are still
increasing. But they start off with much lower emissions per person,
especially India with only 1.8 tons per capita well below world average
of 4.2 tons per capita. They are rapidly industrializing, yes but they
aim to peak emissions well below the European levels and then reduce
rapidly to zero.
Worldwide Co2 emissions for 2016
India remains on track to overachieve on its 2 C compatible target and 1.5 C is within reach India | Climate Action Tracker, see also Guest post: Why India’s CO2 emissions grew strongly in 2017 | Carbon Brief
China
faces the biggest challenge of all, it is expected to meet its
commitments which include 20% non fossil fuel by 2030 and to peak
emissions before 2030 but it has to increase its commitments for us to
have a chance to say within 1.5 C. China | Climate Action Tracker
As
far as I can see the demands of the Extinction Rebellion are not based
on any report by climate scientists. By pushing for nearly impossible
demands they risk a future where we commit to things that we can’t
achieve, instead of committing to things that are possible.
The
thing that has made the Paris agreement such a success is that nations
are able to set policies they know they can achieve at every stage, and
then increase their pledges year on year as they gain experience and
develop new industries to make it all possible. I think we need to
continue in the same spirit. Be ambitious, but make sure our goals can
be achieved when we commit to them.
The
UK government’s plan is to reduce emissions by 80% in 2050. That’s not
enough yet, but if it steps up in its pledge to a 100% reduction, it
would then be 1.5 °C compatible to save the corals UK steps towards zero-carbon economy. This is something we can pressurize them to do. And then to be even more ambitious once they do that.
According
to the IPCC report in 2018, after just a decade or so at 2 °C we lose
99% of the corals, and the reefs probably do not recover. If we don’t go
much above 1.5 °C then 10 - 30% of them remain and they can recover,
though this may take a long time. They can do this because they can
adapt to warmer temperatures, as well as migrate and set up reefs in
places that used to be too cold for them, but at 2 °C the warming is too
rapid for this to work so well.
They
do caution that these projections are not certain and that it’s
possible that corals are more resistant than this, or that we can do
things to help them adapt. See box 3.4, page 230 of their chapter 3.
They
found that no other major ecosystem on Earth is so sensitive, either in
the sea or on land. The corals are the only entire ecosystem we risk
losing at 2 C. Humans for sure are not at any risk of extinction under
any of the scenarios,
There
is a risk of severe impacts on other ecosystems however. In this map
the regions marked in red risk severe impact at 2 °C, and the dark red
regions, at 1.5 °C.
Figure 3.16 of chapter 3 of the IPCC report in 2018.
The
coloured regions highlight risks of sever impact. The gray scale
regions correspond to moderate impacts at those various temperatures.
This
doesn’t mean that the ecosystems vanish. Rather, they change to other
ecosystems. For instance the melting permafrost will lead to a radically
different ecosystem in northern Canada, Alaska and Siberia, in a 2 °C
warmer world, but this warmer world would be more habitable for humans
in the far north, letting us grow crops using conventional agriculture
that never could grow there before. The pace of the change is the main
issue.
It is
important to stay within 1.5 °C for these and many other reasons.
However, our future is a habitable world for humans in all the
scenarios. Indeed it has been greening as a result of the CO2
fertilization effect so far (Rising CO2 has 'greened' world's plants and trees | Carbon Brief).
This should continue through to 2050 at least, with increasing crop
yields, and faster growing trees, some varieties even growing twice as
fast as saplings in the warmer world with the more CO2 rich atmosphere I
will discuss this more later in this article.
It’s
the transition, and the speed of transition that matters, far more than
the end state. Even at an increase of 12 °C then the world is still
very habitable for humans, as we’ll see. What’s more we have already
averted a possible ice age 20,000 years from now, and are headed to a
future where there won’t be any ice ages for hundreds of thousands of
years. That is good because interglacials are far more stable than ice
ages when there are often wild swings in temperature.
The
IPCC do project tens or hundreds of millions of climate refugees and
other serious effects at 2 °C of warning. At that temperature point, we
may get population densities quadrupling in some places in the sub
tropics due to the migrants from the tropics.
That
is a serious societal impact in anyone’s books. However, there is
nothing in the report about collapse of society or an end of
civilization. Those “predictions” are all embellishment by journalists,
which sadly are often just believed “as is” by their readers, especially
young children.
Here is what they say about climate migrants in chapter 3:
Displacement: At
2°C of warming, there is a potential for significant population
displacement concentrated in the tropics. Tropical populations may have
to move distances greater than 1000 km if global mean temperature rises
by 2°C from 2011–2030 to the end of the century. A disproportionately
rapid evacuation from the tropics could lead to a concentration of
population in tropical margins and the subtropics, where population
densities could increase by 300% or more
page 245, 3.4.10.2 The changing structure of communities: migration, displacement and conflict from chapter 3 of the IPCC report in 2018.
This
summary table shows the numbers affected at various temperature
increases. We are currently headed for 3 °C, the last column,
Figure 3.4 page 246 of chapter 3 of the IPCC report in 2018.
Habitat degradation and crop yield change are particularly vulnerable to the difference from 1.5°C to 2°C.
OUR ACHIEVEMENTS IN JUST TWO YEARS
The
situation is undoubtedly serious. However, it is remarkable what we
have achieved and are achieving, and can do in the future, especially
when you look back to before the Paris Agreement in 2016. Back then
admittedly things were dire. The earlier Kyoto protocol agreement based
on carbon trading was a flop, leading to only modest commitments.
But then we had this truly major breakthrough.
What
you need to know is that the Paris agreement only came into place in
2016. They agreed the rulebook for the first time in December 2018, an
essential step before implementing it properly.
When
the US decided to leave, this made only a small dent. Indeed Trump may
well have galvanized the other countries into more action as well as
many cities, companies, states and individuals in the US itself.
In
two years, worldwide, we have already implemented policies to knock an
entire degree off the temperature projected for 2100 from around 4 °C to
around 3 °C.
This
shows what we can do if we work together. If we keep up this momentum
for the next decade, who knows what we can achieve? Might we not be able
to knock another 1.5 °C off the projection for 2100 with our actions in
the next twelve years? After all the whole idea of the agreement is
that pledges increase year on year.
It
is important to keep up the momentum. However, the IPCC made it clear
in their report that 1.5 °C is scientifically possible, is affordable
and is achievable. The main thing required is the political will to do
it.
You so often
hear that politicians are not doing anything. This also is not true.
Some countries already target below 2 °C. The most populous of those is
India, with a population of 1.339 billion, not far off that of China.
It is not far from achieving a 1.5 °C compatible target according to Climate Action Tracker.
That
is a substantial chunk of the world population that is already well on
its way to 1.5 °C. Many of the smaller countries are doing even better
and are already below 1.5 °C compatible.
The
journalists just about always hopelessly exaggerate the IPCC reports
and add numerous embellishments. Even the mainstream news, such as the
New York Times, have their share of exaggerations and misinformation.
A
good example here is the mistake the New York Times made about carbon
pricing. They confused the confused future costs of sea wall defences,
of climate migrants, etc with the incentive tax to prevent emissions of
that CO2, as part of an integrated program. The mitigation costs could
rise to $27,000 a ton by 2100, but the incentive tax to prevent us
getting into this situation at all is estimated at various values of $5
upwards, as part of a mixed program of many measures.
They
weren’t the only ones to make this mistake. The Hill also ran a story
based on this claiming that the IPCC was saying that gas (petrol) would
cost $240 a gallon
This
is such a major misunderstanding. The passage they got the figure is
crystal clear, if you are used to reading scientific papers. It’s hard
to know how the confusion arose. But this is just one of many confusions
in even the mainstream press. Instead of going by what the co-chairs
said, the journalists went through the report, misread a few passages,
and riffed on their misunderstandings without running them past anyone.
Another
major misunderstanding was the claim that the IPCC pathways required
vast amounts of CO2 sequestration using technology we don’t have yet.
Far from it. The pathway to zero emissions by 2050 only had a practical
amount of reafforestation as a carbon negative measure, to offset a
small part of the emissions.
The NY Times title was also click bait: “Major Climate Report Describes a Strong Risk of Crisis as Early as 2040:”. That possible crisis was for coral reefs as early as 2040, not for humanity.
Also,
the central message of the report was that this can be averted with
policies to stay within 1.5 °C, and that this is scientifically
possible, affordable and just needs the political will. That is the
positive side of the report which was not highlighted in headlines, and
barely mentioned in the articles either.
Try watching the videos by the co-chairs and the press conference for the IPCC report in 2018
Watch
the original press conferences and compare with the New York Times
report, and others in the mainstream press at the time, and you wonder
if they went to the same event.
EXPECT CO2 LEVELS AND EVEN YEAR ON YEAR EMISSIONS TO CONTINUE TO RISE FOR A WHILE ON ALL SCENARIOS
Climate
activists often make a big deal of this, giving the impression that our
climate policies can’t be working for as long as we have increasing
emissions.
Yes,
our yearly CO2 emissions are still rising, but that’s not surprising.
All the scenarios project a rise for at least a few more years, even the
ones with 1.5 °C targets. Our current policies and unconditional
pledges will lead to reduced emissions year on year within a few years.
Also,
long after our yearly emissions have declined, we should expect CO2
levels in the atmosphere to keep increasing. It is only when the
emissions reach zero that our CO2 levels and temperature stabilizes,
which even with the 1.5 °C compatible paths doesn’t happen until the mid
century.
With current policies and unconditional pledges we are headed for around 3 °C with a 2/3 chance of staying within 3.2 °C (see summary graphic). That’s just a start. We are bound to get to lower targets than that as they ramp up the pledges.
The bloggers and journalists who share graphs and say “look, we haven’t achieved anything yet” are looking at them with the wrong kind of analysis. This is not a reason to be disheartened.
WHAT IS IT WE HAVE TO DO BY 2030?
Many
of the journalists reported that we have a decade to avoid disaster,
and the more sensationalist accounts say that we risk human extinction,
within a decade.
That’s
not what the IPCC said. It was widely misreported and I think the
journalists have a lot of the responsibility for the current hysteria,
due to the way they mislead the public by not summarizing what they said
accurately.
The report actually said that the best way to 1.5 °C is to reduce CO2 emissions by 45% by 2030.
So,
we have twelve years to reduce emissions by 45%. Nothing much will
happen in 2030. But unless we are already down to a 45% reduction by
then, it will become increasingly harder to remain within 1.5 C by the
middle of the century.
After that we reduce to zero by 2050.
However
if we don’t start those reductions until 2030, we can still stay within
1.5 °C but we have to reduce much more rapidly after that and reach 0
°C by 2045, five years earlier.
That’s
for the 1.5 °C pathway. If we want to stay within 2 °C then it’s much
easier. For that pathway, we need to reduce 20% by 2030 and reach net
zero by 2075.
Also,
reaching zero emissions by 2050 (or 2045) was only one of four ways to
stay within 1.5 °C. We can also overshoot a little (not all the way to 2
°C), and then use negative emissions to get back again, for instance.
Global Warming of 1.5 ºC - chapter 1, figure 1.4
Even
if we don’t manage that, and the temperature briefly reaches 2 °C, it
is possible to get back down to 1.5 °C if we remove CO2 for the rest of
the century to compensate.
This shows conceptually the idea of the two approaches. The best approach is the one to the right,
This is a good summary of some of the main points in the agreement:
HAVE DONE SO MUCH ALREADY
And
- this is hardly utopian as a vision. We have done so much already.
This graph gives an idea of what we have done already. Our current
policies are already well below the “no climate policies” orange region.
Remember most of this has been achieved in only two years!
We
have another ten years to achieve first stopping our current increase
in CO2 emissions year on year, and then the 45% reduction which is the
start of the easier P1 pathway. We can definitely do it. That was the
conclusion of the IPCC report. It’s a matter of politics, not science,
whether we do this.
Of
course the US plan to withdraw. But they are not the largest emitter,
China is, and they are the most important of all to reduce quickly. They
are responsible for half of the extra emissions that caused emissions
to rise again in 2017 after plateauing for a couple of years.
There
the bars show the increases or decreases. As you can see half the
increase from 2016 to 2017 is from China. Graph from here:
As
we’ll see they are fulfilling their pledges under the Paris Agreement -
which is not to stop increasing yet - they only committed to peak some
time before 2030. But that much is really ambitious for a rapidly
industrializing country and they seem on track to do it. We need more
ambitious pledges from them to stay within 1.5 C. But they have
fulfilled their pledges so far.
They have a strong incentive as they are amongst the most affected.
With
“business as usual” then parts of China would get so hot that farmers
can’t work in their rice fields any more during heat waves, and coastal
cities are vulnerable to flooding. So, they are very motivated to do
something about it.
Graphs from: CO₂ and other Greenhouse Gas Emissions
Within the US too, then there is strong support for the Paris agreement in many sectors
The United States climate alliance
accounts for 16 states, as well as the territory of Puerto Rico
committed to upholding the Paris agreement within their borders. Amongst
those sixteen, California if they were a separate country would be the
fifth largest economy.
Cal Facts 2002: Economy
Major
cities around the world have committed to build only zero carbon
buildings by 2030 and to make existing buildings zero carbon by 2050. In
the US that includes New York City and San Francisco:
New York which has 60% of the California economy.
And
the US may well return to the Paris agreement in the future at some
point before 2030. Trump could change his mind, and the next president
in 2022 or 2026 may well return to it, especially with increasingly
clear symptoms of climate change and its effects in the US. That is time
enough for the US government to join in reducing emissions to zero by
2050.
And remember most of this has happened in the last two years. So how much can we achieve in the next ten years?
DEALING WITH SOME POPULAR MISCONCEPTIONS RIGHT AWAY
Before getting to more details about climate change, I’d like to debunk some of the popular misconceptions
DEEP ADAPTATION
Many
have been scared by Jem Bendell’s “Deep adaptation”. He is a
sociologist who relies extensively on Wasdell’s never published non peer
reviewed article. This in turn depends on the now disproved Clathrate
Gun Hypothesis.
This
is the article that is supposedly so depressing it’s driving its
readers to therapy. I can well believed from the panicked and scared
PM’s I get. But the article itself is grounded in junk science. That it
makes people depressed doesn’t mean it is correct.
Indeed,
the climate scientist Michael Mann’s comment on it is just four letters
“Crap”. See the other responses to his tweet too.
I cover this in detail in my article:
UNINHABITABLE EARTH
Others
have been scared by this article and then book by David Wallace-Wells.
He doesn’t write like a scientist. He says himself that he is a general
journalist who has only been interested in climate change for one to two
years.
His book
is just a scrap book of the scariest stories he has found, not a
systematic survey. He misunderstands things, exaggerates, and misses
important nuances in the stories he covers.
The
evidence that climate change is a serious problem that we must contend
with now, is overwhelming on its own. There is no need to overstate the
evidence, particularly when it feeds a paralyzing narrative of doom and
hopelessness. I'm afraid this latest article does that. That's too bad.
The journalist is clearly a talented one, and this is somewhat of a lost
opportunity to objectively inform the discourse over human-caused
climate change.
Michael E. Mann
For more about this see my:
AREN’T HUMANS GOING TO GO EXTINCT IN 2026 OR 2030?
These are fake news stories. One of the worst of the junk blogs is:
He uses quadratic equations, and other polynomials to project! An utterly bizarre idea to a mathematician.
This
image may be enough for you to see how ridiculous his posts are. In the
blue inset I have extrapolated his quadratic (or one very close to it)
both ways so you can see how it will always predict an increase to
infinity in the future and decrease from infinity from the past (unless
it’s the other way around, increase from absolute zero and decrease to
absolute zero) - it is a RIDICULOUS way to extrapolate.:
This blog sadly impresses readers because the credentials of the “contributors” on his deceptive About page seem impressive
It goes on and on, 33 contributors, professors and emeritus professors.
However, click through to the linked names on his About
page, and you realize he credits as a “contributor” all the people
talking in embedded YouTube videos in his blog posts. He surely hasn’t
asked permission of any of them. They probably are not even aware of it.
He just includes this material under the YouTube license for embedding
content.
The other junk scientist who scares many people is
- Guy McPherson, a retired professor of ecology who has lost contact with the scientific method.
You
can tell how far he has gone in the direction of junk science when you
discover he uses Sam Carana’s blog with its daft polynomial projections
as a source for his own predictions!
Guy
McPherson keeps saying the average temperature of Earth is going to
increase rapidly by several degrees in a few months. None of it ever
happens because it is based on junk science like this.
See my Absurd
blog post at Arctic News predicting a ridiculous 10 °C rise in global
temperatures by 2026 - using a POLYNOMIAL to EXTRAPOLATE!!!
You
are not at risk of extinction in any of the climate scenarios. The
worst that happens is that the world gets so hot perhaps you start to
grow coconuts in the Mediterranean and oranges in the UK. Not that you
have coconuts growing in Canada or that humans can’t survive at all.
DIDN’T A 1972 COMPUTER MODEL SAY WE WOULD SOON BE EXTINCT, BY 2040?
This
is a computer program that simulated the world as five numbers for
everything. In 1972 it needed a computer that filled a room. Today it
would run in a fraction of a second on your mobile phone.
It
is just a coincidence. It predicted the number of children would stop
going up because we could no longer find the resources needed to bring
up children any more by now. But it's the opposite.
The number of children is almost the same as it was a decade ago, that’s true.
However,
it is because we have food and other resources for our children, and
have good medicine to prevent children dying and as a result people are
having fewer children worldwide. It is in a background of greatly
increasing life expectancy. Ten to 20 years in the last 50 years.
See
Here is a graph from that page:
The countries with decreasing populations are places like Japan which have a the highest standards of living.
Japan Population | 1950-2018 | Data | Chart | Calendar | Forecast | News
All
this is the opposite of what their model predicted, fewer children
because of poverty and not being able to bring them up, and a situation
of scarcity and hardship, and short lives.
It is just a coincidence.
We
should use the UN population division and other modern well tested and
thoroughly researched projections and modern computers and programs not
this ancient 1972 program that uses only 5 numbers to represent the
entire world!
My article about it is here:
Debunked: No we are not on track for end of world by 1972 computer model
More on this later in the page.
AREN’T WE ALL GOING TO RUN OUT OF OXYGEN TO BREATHE IN A WARMER WORLD?
No not true at all.
There is plenty of oxygen in the atmosphere for many thousands of years and so there is nothing to worry about of that nature.
It’s
not only us that will be fine. There is enough oxygen there for all the
animals in the world to breathe for the foreseeable future even if,
impossibly, photosynthesis ceased completely world wide. This is also
taking account of all the natural processes that remove it. We are fine
for oxygen for thousands of years no matter what happens.
WORLD WITHOUT INSECTS
- Are we headed for a world without insects?
This featured as main story on the TV with a claim that we risked all insects vanishing in 40 years.
But
this is not true at all. It is a case of low quality research with a
dramatic and scary conclusion being promoted through the roof by the
press, and high quality research with the opposite conclusion quietly
ignored or not even noticed.
This
research was immediately criticized by ecologists. It was a not a
systematic survey for one. The researchers just did a search for
articles with “declin*” in the title, so of course they mainly found
articles about declining populations.
They
also found very few studies outside of Europe and the US. For the whole
of China and for Australia the only articles they found were about
honey bees, a domesticated insect. This is like including reports of
declining numbers of sheep in an article on declining numbers of
mammals. Most of their world map was a complete blank.
Those purple bars in Australia and China are for the domestic honeybee
There
were some points in it of interest to academic readers who knew how to
evaluate its limitations, but it should never have got so much
publicity.
A week
or so later the UN biodiversity in agriculture report came out. Their
section on insects was systematic and thorough, based on sent in reports
by experts in many countries reporting to the UN found a mixed picture.
Some stable, some with mixed trends. Some countries reported increases
of pollinators, such as Nepal, and also parts of Europe due to a policy
encouraging flower rich field margins.
They
reported that the German study, which found decreased insect numbers in
nature reserves had lead to a new organization to do something about
it. It is probably due to insecticides and agricultural practices
reducing field margins, so there is much one can do.
The
only habitats they identified with a significant decreasing trend in
insects worldwide were for pastures grazed by livestock.
We
can pollinate the few crops that need pollination using domesticated
insects such as honey bees and the tropical “stingless bees”. But wild
insects add to the diversity and increase crop yields. They reported on
many projects to help improve pollinator diversity.
More on this later.
RUNAWAY GREENHOUSE TO A VENUS HOTHOUSE
- Don’t
we risk making the world as uninhabitable as Venus, by triggering a
runaway greenhouse effect by burning all the fossil fuels?
This
is not true. It was a theory due to James Hansen, who though he is a
climate scientist, has a reputation of exaggerated statements about
climate change. He published this idea, without any calculations to back
it up, in a popular book with no peer review. He did not cite any
published work on the subject in is book.
It was soon disproved. To do that we would have to burn ten times the total reserves of oil, gas and coal in the world.
More on this later.
METHANE BOMB / CLATHRATE GUN
- Others
will tell you that the methane below the ocean floor in the Arctic will
cause a rapid temperature increase of several degrees. There were scientists skeptical of this from the beginning and it is now effectively disproved.
The
methane has been leaking for millions of years, since before there was
ice in the Arctic. The warming temperatures only affect the top 1.6
meters which are indeed very slowly destabilizing, in summer months
only, and they are not able to contribute significantly to global
warming.
More on this later.
MELTING OF POLAR ICE
- Others say that when we have an ice free summer in the Arctic, this will lead to rapid melting of all the ice at the poles.
No that is not true. The sun is always low near the horizon in the
Arctic region and it is dark for half the year, sun never rises at all.
The
extra albedo from ice melting there has a feedback effect locally,
leading to more ice melt in summer than otherwise, but not globally.
Also this is sea ice, floating on the sea, and it melting makes no
difference to sea levels worldwide. This is taken account of in the
models used by climate change and is a minor effect.
SIBERIAN AND CANADIAN PERMAFROST
- Nor can the Siberian permafrost melting do this.
If the temperature goes up a bit, they start destabilizing and add to
the CO2 long term. But they can't warm up the climate enough to
significantly increase their own effects. I
It's
a result of something else, us warming the climate, then a bit extra
added. Not a runaway. And it can go both ways on the 3 C pathway we are
on now. It could be a carbon sink through peat and vegetation growing.
We can also encourage vegetation to help make it more carbon negative by
irrigation. On our present pathway, the range of CO2 emissions is
enough for something between a temperature rise by a fifth of a degree
by 2200 and a temperature drop by the same amount, most of it after
2100. More on this later.
NO KNOWN RUNAWAY EFFECTS
The
sensationalist press make a lot of this, that there are some effects
that are not included in the models such as the Arctic permafrost. What
they ignore is the reasoning that gives justification for leaving them
out.
In a
systematic review by the Royal Society they concluded that there are no
known runaway effects. Nothing that acts like a gun or bomb. Yes, if we
warm the climate and that can lead to some additional warming over long
timescales. But nothing that exhibits “threshold behaviour”.
I go into all of these in more detail with cites in the section DELAYED EFFECTS (below)
The
IPCC say that whenever we stop CO2 emissions, if we ramp down all the
way to carbon neutral, then whatever temperatures we reached by the,
those are the temperatures we are at from then on apart from a tiny
fraction of a degree.
There
may be some temperature rise “baked in” as a result of the masking
effect of SO2 aerosols from coal burning and the like, which cool the
planet down slightly, but if so, it’s only a fraction of a degree,
around 0.15 °C and if we stop the CO2, and remove the black soot (which
has a warming effect) at the same time as we reduce the SO2, we can
prevent even that.
Global Warming of 1.5 ºC - chapter 1, figure 1.5
If
we stop all aerosol emissions, yellow line, there is a short term bump
in temperature by 0.15 degrees, and returning to the previous
temperatures in 20 years and ending with a reduction to 0.25 C below the
present by 2100
Temperatures go down slowly as soon as we reach carbon neutral, depending how you define carbon neutral.
If
you define carbon neutral as continuing to produce enough CO2 to
exactly match the natural negative emissions from all CO2 sinks
including the sea, then temperatures stay more or less level, rising
slightly, the blue line. If it means a net zero anthropogenic emissions
they go down because the excess CO2 in the atmosphere is gradually
removed over time by natural processes, with the yellow and purple
lines.
CURRENT POLICIES - A LITTLE OVER 3 C
According to Climate Action Tracker our current policies keep us within 3.3 °C,
while the unconditional pledges and targets keep us within 3. 0 °C with
a 66% or greater chance of remaining within 3.2 °C. This is their summary graphic
.
“In
the absence of policies global warming is expected, to reach 4.1 °C –
4.8 °C above pre-industrial by the end of the century. ... Current
policies presently in place around the world are projected to … result
in about 3.3°C warming above pre-industrial levels. The unconditional
pledges and targets that governments have made, including NDCs 2 as of
December 2018, would limit warming to about 3.0°C above pre-industrial
levels, or in probabilistic terms, likely (66% or greater chance) limit
warming below 3.2°C.” Temperatures | Climate Action Tracker
As
soon as we stop emissions - that's it as far as temperature increases
go. But the temperature reached, whatever it is, persists for centuries.
From: the IPCC here
Yes,
there are some lingering minor effects such as the Siberian permafrost
or removal of masking effect of anthropogenic emissions. The climate
doomsdayers make a lot of those minor effects and claim they are major
but there is no basis for that as we’ll see.
THE IPCC REPORT IS NOT REWRITTEN BY GOVERNMENTS
This is something that is often said to discredit the IPCC. But it is not true at all.
It
arises from a confusion over the review process for the summary for
policy makers. This is indeed scrutinized line by line by the
governments worldwide as a final stage, but only to ensure that the
report has been summarized accurately for the general public. They do
not rewrite the report itself. This is done at the end after the report
has been finished by the scientists,
There
are three stages, first the experts review the entire report, then
experts together with the governments, and the final stage focuses only
on the Overview chapter.
The governments are involved to make sure that the overview chapter is
"is accurate, well balanced and presents the findings of the underlying report clearly."
It
is most helpful for non scientists anyway and won’t make much
difference to those interested in the background science who will
probably focus on the main report. It does also give you an index into
the rest of the report helping you to find relevant material - they give
the chapter headings and sections in the overview so you can then go to
the sections written by the scientists in the original report to check
what it is they are summarizing.
The
IPCC do not do any research themselves. Rather they are a review body
that looks over the climate change literature of the last several years ,
and scrutinize it carefully, assessing things not just by the number of
studies but their scientific merit and the amount of certainty in their
conclusions. They are widely respected by the climate scientists.
YES WE CAN STAY WITHIN 1.5 °C
In
the 2018 report the IPCC said in their review that we can stay within
1.5 °C if we act right away. They were clear about this in both the
report itself and the speeches made by the co-chairs in the extended
press conference. We need to increase the pledges for the Paris
agreement considerably by 2030, but we can do it. There is a mechanism
in place to increase pledges every year, so this is certainly possible,
if there is the political will.
The graph that came with the report shows this 1.5 °C pathway. It reaches 1.5 °C at 2040 and then levels off. Graph here.
This was hugely misrepresented in the press, even in the mainstream press.
CO2 PRICING MISUNDERSTANDING IN THE NY TIMES
I’ve
already touched on the New York Times report which said that we need
carbon pricing at $27,000 per ton by 2100, confusing mitigation costs
with incentive pricing.
This is what they said:
For
instance, the report says that heavy taxes or prices on carbon dioxide
emissions — perhaps as high as $27,000 per ton by 2100 — would be
required.
Major Climate Report Describes a Strong Risk of Crisis as Early as 2040:
This
has been taken up by many other media outlets and blogs in support of
climate catastrophism and the idea that it is hopeless, or that the
measures are politically impossible to implement.
However this is completely mistaken. The section they got that number from says in its intro
The
price of carbon assessed here is fundamentally different from the
concepts of optimal carbon price in a cost–benefit analysis, or the
social cost of carbon
2.5.2.1 Price of carbon emissions from Global Warming of 1.5 ºC, chapter 2, page 152
In
the rest of the intro, they explain that what they are referring to
here is the cost of mitigating the effects of that extra ton of CO2.
To
unpack this a bit more, then, for instance, if our CO2 emissions lead
to a sea level rise, that $27,000 would include a contribution to the
cost of all the sea barriers to contain the rising sea through to 2100.
It is a completely different idea from the pricing you need to use as an
incentive to stop emitting the CO2, which is only one of many measures
you might use in a combined program. Some countries use carbon pricing,
others don’t.
Later
in that very same section from the IPCC that the NY times misquoted,
they talk about an incentive price, and they make various suggestions,
mostly in the range of $5 to $50 or so depending on whether it is used
on its own or as part of a larger program of measures. Taking the US
electrical sector as an example they say
Furthermore,
a mix of stringent energy efficiency policies (e.g., minimum
performance standards, building codes) combined with a carbon tax
(rising from $10 per ton in 2020 to $27 per ton in 2040) is more
cost-effective than a carbon tax alone (from $20 to $53 per ton) to
generate a 1.5°C pathway for the U.S. electric sector. Likewise, a
policy mix encompassing a moderate carbon price ($7 per ton in 2015)
combined with a ban on new coal-based power plants and dedicated
policies addressing renewable electricity generation capacity and
electric vehicles reduces efficiency losses compared with an optimal
carbon pricing in 2030.
2.5.2.1 Price of carbon emissions from Global Warming of 1.5 ºC, chapter 2, page 153
(to make it more readable, I removed cites and rewrote USD2010 to $ and tCO2 t−¹ to “per ton”)
The
NY Times journalist just cherry picked one paragraph with that high
number in it, without understanding its context at all. Yet this has
been taken up by so many other blogs and articles.
Search Google and this is the top result, a search snippet highlighted by Google’s algorithm:
The Hill reports it the same way as the NYTimes:
The IPCC claims in its latest report
that action must be taken to avert global warming of 1.5 degrees
Celsius by the end of the century — a benchmark it says comes with
costly climate consequences. Its recommendation: a carbon tax of as much as $200 per ton of carbon dioxide emissions by 2030 to an astonishing $27,000 per ton by 2100.
For
America families, this could mean the price of gasoline soaring to $240
per gallon. Remember when we thought $4 per gallon was high?
Gas at $240 per gallon? IPCC report lays out high cost of carbon taxes
And a Google search turns up many more articles and blog posts saying the same thing
This is all completely mistaken, as you can see from the quotes from the IPCC report itself that I just gave.
FOUR WAYS TO GET TO 1.5 °C
What
they actually said is that if we cut CO2 emissions rapidly in the next
12 years then we can achieve a 1.5 °C rise easily. If we don't do that,
it is hard to avoid 2 °C by 2050 to 2060 though we can still get back to
1.5 °C by burning lots of biofuel and capturing the CO2 from burning it
for the rest of the century and other forms of carbon capture and
storage. They looked at four different ways of staying within 1.5 °C.
The
best is to cut emissions quickly especially since coral reefs are
nearly extinct after just two years at 2 °C and delayed reductions mean a
few years at 2 °C.
These
are the four main pathways the cover in the report, in their
investigation of ways to remain within 1.5 °C. (That’s the goal of the
Paris agreement and they were tasked with both finding out what was
needed to remain within this, and what the difference is between effects
at 1.5 °C and 2 °C)
The
P1 pathway assumes rapid reduction by 45% by 2030 and then a reduction
to to 0% emissions by 2050. It never requires a negative emissions in
total, but some of the CO2 is offset by negative emissions through
afforestation shown in brown in the diagram. Which is already going on,
China particularly is doing a lot of afforestation.
(The
yellow in these diagrams is active removal by continually recycling the
trees in forests by burning biofuels and capturing the CO2)
I
shared this graph before, but let’s look at it again, which shows
conceptually the idea of the two approaches. The P1 path is like the one
on the right, and the other ones have increasing amounts of temporary
excess like the one on the left:
The
other main alternative they discussed involves reaching 2 °C at around
2050-2060 but then for the rest of the century we use carbon capture and
storage.
However
they were widely misrepresented in the press with a claim that they
required as yet unproven expensive methods for taking carbon directly
from the atmosphere. This is not what they said.
Instead
they said we could do it by growing vast forests for fuel and then
burning that fuel in plants that capture the CO2 emissions from the fuel
burning. This works because the trees as they grow take CO2 from the
atmosphere and as they are burnt the CO2 is then captured and the next
generation of trees repeats the process.
It
would be a huge challenge to do that, but it is known technology. The
main thing would be scaling up the carbon capture and storage for the
emissions from the wood burning power stations. But that’s far easier
than taking it out of the atmosphere with several plants already doing
this.
The main
disadvantages of this second approach, apart from the expense and
complexity, is that it means that the corals are nearly extinct at 2 °C
and it just takes a couple of years at that temperature to kill most of
them to the extent that recovery is difficult.
The
other two ways they discuss in the report are a mix of some early
reductions and some reafforestation and biofuels with later carbon
capture and storage, with more capture needed if the early reductions
are less.
They
didn't find any other ecosystems that are as sensitive as the corals.
Not even the mangrove swamps which was one of the other ones they looked
at for climate sensitivity.
The
2018 report was actually a little more optimistic than expected, if
anything. They raised the CO2 emissions level needed to stay within 1.5
°C due to re-examining of past data. See
THICK LAYERS OF ICE TAKE A VERY LONG TIME TO MELT - CENTURIES TO MILLENNIA
When
our emissions reach a net zero (no more added than is removed) then the
temperature increases stop and then start to go down as the CO2 levels
reduce. However the world does continue to change and there is a lot of
lag there, mainly because of the ice, and the ocean.
The
permafrost would continue to melt as would the ice in Western
Antarctica and Greenland. That’s a slow process because ice has huge
thermal inertia.
Icebergs
can spend months, and longer, in warm water before they melt. There are
lakes in New Zealand that often gets icebergs from glaciers and once
there they continue for ages. Bizarrely you get ice bergs in warm water
in summer.
Those
are icebergs in the full sunlight of a New Zealand summer day. So think
how slowly ice must melt in the far colder conditions at the poles.
The
poles will still experience the six month polar winter every year and
only glancing sunlight even in the Arctic or Antarctic summer. So, yes,
the ice in Greenland and Antarctica will melt eventually, until it
reaches whatever level of cover is in equilibrium with the climate. But
this is an immensely long process.
The
Greenland and Antarctic ice will persist for a long time in a warmer
world for much longer than the year or two of those New Zealand
icebergs. Indeed both will be covered in kilometers thick layers of ice
for tens of thousands of years in any of the future scenarios. It just
takes that long to melt so much ice in a slightly warmer world.
The
sea level continues to rise partly from this ice melting, and partly
also from the sea warming up. The sea has a huge thermal capacity and
will gradually take up heat from the atmosphere but that’s another
thousands of years process. The warmer sea expands. For the smaller sea
level rises about half the sea level rise is from the sea expanding
rather than ice melting.
All
that would continue, if we stopped emissions right away, but at a
lesser rate than if we were going to a warmer world. About 15- 40% of
the emitted carbon remains in the atmosphere for 1000 years.
However
none of this changes the situation that the world is slowly cooling as
soon as emissions stop in the 1.5 °C scenario or most scenarios that end
up with zero emissions. Even as the ice melts, the world is cooling
down, as CO2 gradually comes out of the atmosphere dissolved in the sea,
taken up in peat bogs, swamps and salt marshes, in the soil as it
builds up, and so on.
REMOVING CO2 THROUGH RE-AFFORESTATION
We
can also remove CO2 from the atmosphere more rapidly, by burning wood
and then using carbon capture on the CO2 produced - every time you do
that it takes some CO2 from the atmosphere.
We
can also remove CO2 by re-afforestation, and reversing desertification.
Improving the soil also takes CO2 out of the atmosphere, as does making
forests more species rich.
If
eventually for instance we regreen the Sahara desert back to the way it
was 5000 BC when it was pastureland rather than desert - that would
take large amounts of CO2 from the atmosphere.
The Sahara dust fertilizes the Amazon. Massive amounts of Saharan dust fertilize the Amazon rainforest But 11000 to 5000 BC then the Sahara was green.
Green Sahara: African Humid Periods Paced by Earth's Orbital Changes
So the Amazon jungle can manage fine without the Sahara dust or less of it.
We are already doing afforestation as part of the measures to deal with climate change.
China planted nearly 79 million hectares by 2015. Under the Bonn Challenge,
56 countries, from central and south America mainly, are pledged to
restore 350 million hectares of forest by 2030. All four of the IPCC's
scenarios for remaining within 1.5 °C involved some measure of
afforestation.
In a
recent study reported in Scientific American, researchers who planted a
mix of trees rather than a single species found that they removed 32
tons per hectare instead of the more usual 12 tons.
Reverting
non forest land to forests globally could offset around 253 billion
tons of CO2 between 2018 and 2100, which is equivalent to seven years of
global CO2 emissions at current levels.
Carbon
brief have a map of where reafforestation is happening around the world
and with a summary of the research, and the opportunities and
challenges here.
Mapped: Where ‘afforestation’ is taking place around the world
EFFECT OF CO2 ON PLANT GROWTH
Trees and plants grow faster in a world with more CO2 due to the CO2 fertilization effect
Trees
increase in productivity by around 23 percent over pre-industrial and
crops boosted by 11.5 percent for most, like wheat and rice but some
like corn which use a more efficient form of photosynthesis can’t
benefit so much from the extra CO2 because they are so efficient at
fixating CO2 already and are only boosted by 8.4 percent.
A downside is that food crops can lose a significant amount of zinc and iron in a warming world and grains also lose protein.
Ask the Experts: Does Rising CO2 Benefit Plants?
There’s
a likely increase of productivity of trees by 23 to 28% until 2050. But
the responses are more pronounced in young trees.
Also
a study of European trees in 2018 found that though the volume
increased by 29 to 100% (up to a doubling of the volume added) the
density decreased by 8 to 12 percent.
So they produce much more wood, but it tends to be lighter, offsetting some of the gains.
Trees and climate change: Faster growth, lighter wood
Grasses
also increase in productivity with more CO2, but it depends on the
species. One study for instance found that the optimal levels of CO2 for
grass depend on the species
“We
found that the optimal CO2 concentrations occurred at 945, 915, and
1151 ppm for the aboveground biomass of tall fescue, perennial ryegrass,
and Kentucky bluegrass, respectively.
The optimal CO2 concentrations for the growth of three perennial grass species
Overview of some of the research through to 2012 here:
The effect can also be seen from orbit with satellite measurements. Leaf area is increasing.
This
greening is a combination of new leaves on existing plants as well as
an increase in the amount of land covered by plants and shrubs. Only a
few areas, less than 4%, show a browning effect. Many areas have an
increase of more than 50%.
Rising CO2 has 'greened' world's plants and trees | Carbon Brief
The researchers estimated that 70% of the extra growth is due to rising CO2 in the atmosphere.
Another
8% is due to climate shifts in temperature and rainfall patterns,
especially for high latitudes like the Tibetan Plateau and the Sahel
region in Africa.
The
Arctic is getting greener of course because of the melting permafrost.
And the Amazon jungle areas are too however, interestingly.
Then
the rest is due to effects such as more nitrogen in the soil from
fertilizer, changes in forest cover, grazing and intensive farming.
This is a video summary:
SOIL IMPROVEMENT
It
is possible that soil improvement also could make a big difference. As
the soil is improved, CO2 is taken up from the atmosphere.
The
amount that can be removed in this way is hard to estimate, but it
could remove 200 Gt by 2100 which could increase to 500 Gt by techniques
such composting (rather than burning) soil revenues, limited tilling,
and mixing biochar. Currently human activities are running at just under
37 Gt in 2017. So, soil improvement could take up between 5 and 13
years of emissions at 2017 levels. I got those figures of CO2 emissions
from here:
This is a summary in a recent review from 2018 of CO2 removal methods:
"In
addition to mixing biochar into soils, recent studies have focused on
replenishing or enhancing organic carbon in cultivated soils through
various agricultural practices, such as limiting tilling, and composting
(rather than burning) crop residues. … Earlier studies suggested a very
limited possible role for soil enrichment; however, more recent
analyses suggest a physical removal potential of ~200 Gt(CO2) by 2100, …
and this could possibly be increased up to 500 Gt(CO2) by practices
such as soil carbon enrichment at greater depths. …“
Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals
WHAT IS THE WORST CAN HAPPEN?
We
continue to have winter and summer in all the scenarios - this does
nothing to the tilt of Earth which leads to the changes of temperature
between summer and winter. Where I live on the Isle of Mull, we have
less than seven hours of daylight in the middle of winter, while in the
middle of summer it gets so light at night that the entire night counts
as twilight, never reaching complete darkness. That won’t change.
We will still have six month long winters of total darkness at the poles.
The
Himalayas are also always going to be cold in all the scenarios even
with no climate policies at all. Tibet, Mongolia, the high Andes, the
Alps, these are all going to remain cold in all scenarios, if warmer
than before.
The
ice in Greenland and Antarctica is still there for thousands of years in
a warming world as it takes that long to melt it all. The Arctic sea
ice can melt in summer at the highest temperatures but in winter when
the sun never rises at all it will still be very cold in the Arctic.
It’s a world of less ice and fewer glaciers but not no ice. So clearly not an uninhabitable world on any scenario.
The
idea that even the worst of climate changes would make humanity extinct
is utterly ridiculous. It often comes from James Hansen's exaggeration
in his book "Storms of our grandchildren" published in 2008 and still
available to buy at Amazon. It says incorrectly
“After
the ice has gone, would the Earth proceed to the Venus syndrome, a
runaway greenhouse effect that would destroy all life on the planet,
perhaps permanently? While that is difficult to say based on present
information, I’ve come to conclude that if we burn all reserves of oil,
gas, and coal, there is a substantial chance we will initiate the
runaway greenhouse. If we also burn the tar sands and tar shale, I
believe the Venus syndrome is a dead certainty”
Page 236
James
Hansen is a climate scientist, but he is well known for his hugely
exaggerated statements not based on any peer reviewed research. This is
an example. It was just speculation which he could publish in a book
without going through peer review.
After
his book was published, researchers quickly disproved it. But his book
is still on sale and still quoted even though everyone in the topic of
climate change knows it is wrong. For the background to this see my
The
journalists, politicians, public figures who put their weight behind
the climate change lobby, they often exaggerate. Even the ones doing
good science and the ones of high reputation like David Attenborough -
they use hyperbole to try to get politicians to act.
THE HURRICANES, HEAT WAVES, FIRES, AND FLOODING ARE NOT GLOBAL EVENTS
I’d
like to do a bit of an aside here to help people who are panicking
about this. I often get people contact me scared of things that couldn’t
possibly do anything to them. This may be obvious once I say it but it
needs to be said for some people who are really scared and not thinking
clearly, also for very young children.
You
will get natural hazards like the fires, heat waves, flooding and
hurricanes. And we’ll get more of those as a result of climate change.
But don’t think of them as covering the entire world. That just can’t
happen.
For instance, you are not going to get a heat wave at all if you live somewhere really cold like lose to the Arctic circle.
You
aren’t going to get a proper hurricane if you live in Europe, because
hurricanes cross the Atlantic from West to East and never make landfall
in Europe (strong winds yes, hurricanes proper, no).
You aren’t at risk of a forest fire if you live in a place without trees.
The
sea in worst case rises meters by 2100. The IPCC talks about it being
feet, but it is possible it could be higher than their estimate because
they caution that the science is not yet well settled on this. But not
tens of meters for sure. And not the kilometers rise needed to swamp the
entire world - there isn’t enough ice to melt to do that ever.
For
instance this is what happens to Florida with a three meters sea level
rise. This is much higher than the IPCC projection for 2100 of two to
four feet, and although that is regarded as conservative, it’s not
likely it’s as much as three meters.
Florida
before and after a 3 meter sea level rise due to melting ice from the
Antarctic and Greenland ice sheets. Image made using the Eustatic Sea Level Change tool from Virtual Earth System Laboratory (VESL).
Florida is a low lying state, yet most of Florida also is untouched at a three meters rise.
If
you live in the Florida keys or Miami, yes you may have to move house.
Florida is especially vulnerable because the land is porous limestone.
For New York, or Netherlands they can build higher flood barriers. For
these low lying areas in Florida the worst case is you move out or build
upwards (e.g. artificial islands) or get used to Miami having flooded
streets at extreme high tides.
So,
yes that can happen. But I get people worried about sea level rise who
live nowhere near the sea. It doesn’t mean that the entire surface of
the Earth is covered in water to a depth of one meter. You are only at
risk if you are in a city that is already close to being flooded.
Also
for people who do live close to sea level, just a meter or so above the
high tide mark - it is only a risk of flooding at the highest tides
with storm surges to start with. Even with a one meter rise or more, you
are not going to be flooded at low tide or indeed, any time except the
highest spring tides once a lunar month with assistance of storms.
The
worst case is you have to evacuate Miami or convert it into a city that
is a bit like Venice during the occasional high tide storm surges with
sea filling the streets.
Everyone
else, then it’s just like normal flood warnings, wildfire warnings,
heat wave warnings and hurricane warnings, but maybe more of those in
the future.
The
wildfires are only a risk if you are in a place like California already
at risk of fires. It’s not talking about fires, and flooding sweeping
over the entire world, or of a global hurricane that affects everyone
worldwide - no such thing is even possible.
THE RCP’S - TARGETING 1.5 °C, 2.4 °C, 3 °C AND 4.9 °C
Let’s
look at the “RCP”s or Recognized Concentration Pathways. These are
detailed scenarios worked out so that climate modelers can run their
models on the same projections for comparing them. If it weren’t for
them, everyone would use different scenarios and it would be almost
impossible to either compare models or aggregate them together for
statistical results.
- RCP 2.6: reach 1.5 °C, ~490 ppm CO2
- RCP 4.5: reach 2.4 °C, ~650 ppm CO2
- RCP 6: reach 3 °C,~850 ppm CO2
(with existing policies and unconditional pledges we are headed for around 3 °C). - RCP 8.5: reach 4.9 °C, ~1370 ppm CO2, “Business as usual”.
(We are already well within this one, by existing policies alone)
For details:
This shows how the CO2 levels vary with the different RCP’s and the emissions which are the inputs to the models:
They are all pretty much indistinguishable up to 2020.
I got these graphs here:
If
you look at the latest data - we are on the same curve as RCP 6.0. But
it’s also on RCP 4.5 and 2.6 - the 2 °C and 1.5 °C pathways. We just
can’t tell them apart yet from the graphs but by analysing policies we
are on the path for a 3 °C rise by 2100 :
From Analysis: Why the IPCC 1.5C report expanded the carbon budget | Carbon Brief
This
shows how the atmospheric CO2 and the temperature and sea level rises
over a longer time period through to 2500 with the four scenarios. In
the RCP 8.5 then there just aren’t enough fossil fuel reserves to keep
burning them for ever which is why that curve is shown as leveling off
at 2000 ppm in 2200 for “business as usual”.
Topic 2: Future changes, risks and impacts
Notice
how when the atmospheric CO2 levels stop rising, the temperatures
almost immediately level off in all the scenarios. However the sea
levels continue to rise in all the scenarios except low CO2, for
centuries.
Those sea level rises are difficult to model and could be up to several times larger.
So
anyway that's what the IPCC say in their summary of the research on the
topic for the last few years. 1.5 °C is definitely in reach if we have
the political will. It requires ramping up pledges rapidly in the next
several years through to 2030. But the aim is to ramp up.
If
we stop CO2 emissions, then whatever temperature it is is where we
level out. If we could stop all CO2 emission today then we would level
of at 1 °C above pre-industrial and then it would gradually decline.
We
are not going to be able to stop instantly, that isn’t going to happen.
But it shows that the rise is not inevitable until we actually reach
those temperatures. That is the conclusion of the IPCC.
DELAYED EFFECTS
So now, let’s look at those delayed effects, that the doomsday sayers / climate catastrophists make so much of.
CLATHRATE GUN HYPOTHESIS - EFFECTIVELY DISPROVED
Many
of those posts that say we have a much higher temperature rise baked in
rely on the clathrate gun hypothesis, which is effectively disproved
now.
This is how it is supposed to work:
Clathrate gun hypothesis scenario
The
clathrates are a form of ice with methane locked inside it, on the
floors of the Arctic ocean. It floats in water like ordinary ice, so any
that remains on the sea floor has to be bound to the sediment. It’s
stable at higher temperatures than ordinary ice, up to a few degrees
depending on pressure. There are thick deposits frozen into the sea bed
below the Arctic ocean. The only ones that matter are the ones within
100 meters of the surface. Any deeper and the methane dissolves out of
the bubbles into sea water on the way up to the surface as the sea is
very undersaturated in methane.
However
it’s now known that only the top layers of the clathrates are warm
enough to start to destabilize only the top 1.6 meters and they do so
only very slowly (centuries) because they are only warmed sufficiently
for less than half the year - and this doesn’t seem to be enough for
fast destabilizing.
There
have been skeptics all along- it is thermodynamically difficult because
it's an endothermic reaction - the opposite of the idea of an explosion
you get from the word "gun". If you try to get it going, some will
dissociate, absorb the heat and that will cool down the rest and it just
stops. Carolyn Ruppel, lead author of the USGS metastudy puts it like
this:
So
the deposits locally can't explosively dissociate. It would need a huge
feedback into the global climate to do this, but the metastudies show
that this just isn't present. Instead it is a very slow burner over
thousands of years, not even much affected by the increasing
temperatures, since they have been warm enough to destabilize already
for thousands of years.
The USGS metastudy in 2017 by the USGS Gas Hydrates Project concluded
"“Our
review is the culmination of nearly a decade of original research by
the USGS, my coauthor Professor John Kessler at the University of
Rochester, and many other groups in the community,” said USGS
geophysicist Carolyn Ruppel, who is the paper’s lead author and oversees
the USGS Gas Hydrates Project. “After so many years spent determining
where gas hydrates are breaking down and measuring methane flux at the
sea-air interface, we suggest that conclusive evidence for release of
hydrate-related methane to the atmosphere is lacking.”
Gas Hydrate Breakdown Unlikely to Cause Massive Greenhouse Gas Release,
That’s
from the big USGS review in 2017, and the Royal Society did one too and
then in 2018 the big gas hydrates research project CAGE finally proved
that the methane has been leaking gradually for millions of years and is
not a new thing . It is pretty much settled. It’s not even a
consideration at all for climate modeling now.
For
more about this see this, my update of the Wikipedia article which is
now very dated on this topic and sadly they don’t seem likely to update
it any time soon, so I’ve done my own update of it in our Doomsday
Debunked wiki to include the latest research from 2017 though to 2018:
SIBERIAN AND CANADIAN PERMAFROST
More recently those who say that the IPCC have left out big unknown effects have switched to the Siberian permafrost.
This
is nothing to do with the clathrate gun hypothesis. Indeed, it is not
about methane clathrates at all - there is some methane locked into the
permafrost already, but not a lot.
Instead
it’s just ordinary ground filled with grass, other vegetation, bodies
of animals (including mammoths in Siberia) and other creatures that have
been frozen for thousands of years. Also a lot of it is just frozen
peat. As the climate warms up then gradually the permafrost melts. It's a
slow process. As that happens those organics are exposed to liquid
water and the atmosphere. Parts that are dry produce CO2, but can also
take up CO2 from the new vegetation that grows on them. Also as the
permafrost melts, peat will start to grow over large areas and peat
growth takes up a lot of CO2.
Parts
that are wet, not well drained, can produce methane because in wet
conditions somewhat blocked off from the surface, without access to air,
then decomposing microbes tend to produce methane instead of CO2. They
do that just because there isn't any oxygen available to make the CO2.
So it attracts different kinds of microbes that produce methane instead.
Because
the methane is produced below the surface, most of it gets converted to
other organics and to CO2 as it gradually percolates towards the
surface.
Figure taken from this paper
showing some of the processes. The methane is produced deep
underground. It gets involved in many chemical reactions. Methane is
produced in anaerobic conditions conditions without much oxygen - and it
is consumed in aerobic conditions.
This makes it really hard to estimate what would happen as it melts, because there are so many different processes going on.
If
the melting is reasonably slow, on the 3 °C pathway we are on, it can
be anything between an increase by a fifth of a degree on top of global
warming by other causes by 2200. Only a fifth of a degree and most of
that after 2100 - that's the highest figure in the models looked at. The
lowest it can be is a carbon negative contribution corresponding to a
reduction in temperature by a fifth of a degree over the same timescale.
Also
we may be able to influence what happens by drainage or irrigation. For
instance damp ground may encourage peat formation which takes up CO2
If
we were to discard all our climate policies and return to "business as
usual" then all the models show a positive CO2 contribution but it can
be anywhere between negligible and about a quarter of a degree of
contribution by 2100.
Although
potentially this is quite a large effect, it’s only a fraction of a
degree. The research is conflicting but while laboratory experiments
tend to suggest that it will release a lot of carbon, a fair bit of the
actual field research, looking what happens when it melts, suggests it
could be carbon negative at a 3 °C rise. The modeling also suggests that
this is well within possible.
I cover the details here.
ARCTIC ALBEDO - ALREADY INCLUDED IN THE MODELS
There
are several other things like that including the Arctic albedo. This is
about the way that when ice melts, the ocean becomes less reflective,
because it’s not covered in that white stuff, and so absorbs more heat.
The climate doomsdayers make a lot of that but it is already included in
the IPCC models. It is a minor effect globally.
The
ice only melts in the Arctic summer - rather obviously when the sun is
below the horizon throughout the arctic winter any albedo effect is non
existent because of the permanent night. That will be true no matter
what happens.
The
albedo effect is only really relevant to the melting of Arctic ice in
summer - it makes the water slightly warmer so increasing the amount of
ice melting. It is important to polar bears and walruses mainly. But
even in summer the sun is low on the horizon in the Arctic and not that
much heat is absorbed by the ocean. It matters locally but globally it’s
not a significant effect.
The
Arctic will probably become ice free in summer occasionally, some time
mid century but it is not likely to become ice free in winter at all,
not on any projections I've seen. The IPCC do take account of albedo
effects of ice and snow.
RESILIENCE OF AMAZON FOREST
Another
such effect is the effect of the Amazon forest die back but that is now
thought to be much less than previously estimated. They didn't take
account of the effect of the mix of species some of which are more
resistant to heat changes than others. See this paper in Nature from
2016
Then
another factor is that some patches of the forest are more resilient
than others.If it was a monoculture the climate would just need to go
over some threshold in temperature, or humidity, and the whole thing
would go. Because of the mix of species then it is more of a gradual
thing. And then because of the patchiness, it would change to grassland
only in patches which protects it further. Also parts of it seem to be
much more resilient, especially the western part of the Amazon
rainforest, and this is how it survived previous warm periods, so it’s
now thought most of it would survive this time too. See this paper in
Nature for some of the recent research from 2018:
So
in short, the composition of parts of it would change. Some might
change to a more open drier grassland. However most of it would remain
and there would be a lot of tropical rainforest still at 3 °C or even at
the higher temperatures of “business as usual”.
The
IPCC review doesn't take account of papers on these topics for detailed
projections but it does take account of them in separate sections
looking at how much they might affect the conclusions. And the result in
the reviews is that they have some effect but it is minor enough that
it doesn't matter that they leave them out. So they have a reason for
leaving them out.
This is often not mentioned by those who criticize them for this.
What
they do is a careful systematic review. That's their job. And that also
is why it takes so long, it's easy to do a hasty non systematic review
like those of their critics, but not so easy to do a careful systematic
review.
The IPCC
don’t actually do any research themselves. The people who do the review
are experts who do their own independent research of course, but that’s
not their role in the IPCC, it is to do a systematic thorough review of
the researches by others over the last several years.
This
is why I rely on the IPCC over the people who do their own independent
analysis. I’m no expert myself and they are people who have spent years
of their life studying the material to make the most accurate assessment
they can. And when there are differences of results and views in the
literature, they do not just pick one favoured one. Rather, they
summarize the range of results or say things such as “high confidence”
if there is general agreement or “low confidence” if there are diverging
views or if the research has gaps in it.
And
yes, scientists who do the climate change projections acknowledge that
there are some things they leave out of their projections. This is true.
What the critics often don’t mention is that they give reasoning about
why they think it is okay to leave them out.
THERE ARE NO KNOWN RUNAWAY FEEDBACK EFFECTS
Journalists
sometimes refer to “feedback” when they really just mean amplification.
A 3 C warmer world may have a fifth of a degree extra temperature rise
from Siberian permafrost by 2200. But that is not a runaway effect -
that extra warmth is not enough to significantly increase the melting of
the permafrost. If we stop human emissions of CO2, it will just warm by
an extra fraction of a degree and then stop.
In
this quote then “threshold behaviour” refers to the idea that once you
reach a particular temperature some runaway effect will arise that
commits you to a much higher temperature. In a systematic review, no
such effects are known.
See Royal Society review of research from 2017
Permafrost:
…. This led to a new estimate that about 100 Pg of cumulative carbon
emissions (with a wide uncertainty) would be released from thawing
permafrost by 2100 under RCP8.5. This leads to a significant positive
feedback, but the review emphasized that emissions are “likely to be
gradual and sustained rather than abrupt and massive”. A recent modeling
study estimated that permafrost carbon releases could contribute up to
12% of the change in global mean temperature by 2100 Studies since 2013
therefore confirm the importance of permafrost carbon release as a
positive feedback, and the need to include it accurately in Earth system
models, but they do not support considering it to exhibit threshold
behaviour.
Clathrates: Some
economic assessments continue to emphasise the potential damage from
very strong and rapid methane hydrate release, although AR5 did not
consider this likely. Recent measurements of methane fluxes from the
Siberian Shelf Seas are much lower than those inferred previously. A
range of other studies have suggested a much smaller influence of
clathrate release on the Arctic atmosphere than had been suggested. …. A
recent modeling study joined earlier papers in assigning a relatively
limited role to dissociation of methane hydrates as a climate feedback.
Methane concentrations are rising globally, raising interesting
questions (see section on methane) about what the cause is, finally new
measurements of the 14C content of methane across the warming out of the
last glacial period show that the release of old carbon reservoirs
(including methane hydrates) played only a small role in the methane
concentration increase that occurred then.
Amazon rainforest:
The processes acting on tropical rainforests are very complex and a
recent review still emphasised the possibility of a climate threshold …
Recent work using a detailed ecosystem model (Levine et al., 2016)
supports the possibility of a significant but heterogeneous transition
in biomass type dependent on the length of the dry season, but in a
continuous rather than “tipping point” manner. Resilience may be
underestimated if plant trait diversity is not included in models
ACIDIFICATION OF THE OCEANS - WINNERS AND LOSERS
The
oceans are getting more acidic. But they are still alkaline rather than
acid and will remain more alkaline than acidic in the future too. So in
a way it is a bit of a misnomer. Not actually going to get a pH lower
than 7, but less alkaline than they are now.
At
times our oceans in the past have been more acidic and they have had
sponge reefs, and corals go extinct. At other times they are more
alkaline and have corals as today, and sponge reefs are rare.
Some species will benefit from acidification, for instance sea grasses. The NNOAA put it like this:
Ocean
acidification is expected to impact ocean species to varying degrees.
Photosynthetic algae and seagrasses may benefit from higher CO2
conditions in the ocean, as they require CO2 to live just like plants on
land. On the other hand, studies have shown that lower environmental
calcium carbonate saturation states can have a dramatic effect on some
calcifying species, including oysters, clams, sea urchins, shallow water
corals, deep sea corals, and calcareous plankton. Today, more than a
billion people worldwide rely on food from the ocean as their primary
source of protein. Thus, both jobs and food security in the U.S. and
around the world depend on the fish and shellfish in our oceans. What is Ocean Acidification?
The
polar oceans are predicted to be the first to become acidic enough to
make a significant difference, to become undersaturated with respect to
carbonate. Moluscs are resilient to the ocean acidification. But some
tiny creatures are more vulnerable. So also are corals. That’s because
they use aragonite, an especially soluble form of carbonate.
Corals
generally need the aragonite saturation index to be at least 3. They
can manage at lower values but are particularly vulnerable to coral
bleaching because at lower values then the bleached coral starts to
dissolve away. So as the oceans get more acidic, then corals will be
more vulnerable to bleaching events.
That’s partly why they are so sensitive to temperature changes.
Some
coral reefs already live in conditions of much lower pH of 7.8 instead
of 8.1 due to volcanic carbon dioxide seeps in Papua New Guinea. This
corresponds to an increase to 750 ppm by 2100, a likely level to reach
with current policies).
They
were able to survive with constant coral cover but different species
mix and less structural coral though the same amount of cover. But at pH
7.7 the reef building ceased.
It’s
a combination of the warming and the acidification. Corals can respond
by moving to colder places but not if the change is too fast. See the
section on ocean acidification in this review for more details:
It
may be possible to help save some of the coral reefs from the worst
impacts by actually growing coral larvae in the lab and then
reintroducing them to coral reefs to revive them.
Amongst the most vulnerable species are the sea butterflies or pterapods. Tiny planktonic creatures.
They
use aragonite, an especially easily dissolved form of calcium
carbonate. Their shells are already dissolving in our slightly more
acidic oceans in some parts of the world, as was shown in this study in
2012.
However
as an example of how this is work in progress, recent research
published in 2019 shows that they are able to cope with this even when
the outer shell dissolves away completely, by thickening the internal
shell wall. Though it likely has some metabolic cost, the pteropods are
surviving as the oceans become more acidic.
Pteropods counter mechanical damage and dissolution through extensive shell repair
They conclude their paper
We do not claim that L. helicina
will be immune to ocean acidification on account of their ability to
maintain their shells, but propose efforts should shift to assessing the
metabolic cost of repair calcification when predicting the tolerance of
this species to future environmental conditions.
There
is no doubt that ocean acidification will lead to major changes with
some species being badly effected and some benefiting from it. The
details are complex with much research still to be done.
It’s
a significant issue but we are not talking about uninhabitable oceans
or all the ocean creatures dying or anything like that.
The Wikipedia article is a useful source for cites on this
ANTHROPOGENIC AEROSOLS
This
is the idea that aerosols from burning coal and other human activities
can have a cooling effect and may be masking some “baked in global
warming” due to a dimming effect.
However
it is more complex than just a masking effect. The SO2 has a cooling
effect while soot and other black organic compounds have a warming
effect. The aerosols also don’t decrease to zero when you stop burning
coal, but rather, a gradual reduction.
They
do partly offset the mitigation efforts in the early stages. In the
latest IPCC report they say that the deep reductions that stay within
1.5 °C with no or limited overshoot have to include deep reductions in
methane and black carbon, 35% or more of both by 2050 relative to 2010.
When you do that then the cooling aerosols are indeed also reduced and
this partially offsets the mitigation measures for two or three decades
This shows the sharp reductions in methane and soot needed for the 1.5 °C path:
This
is both good for health and also has a cooling effect which is indeed
offset to start with by the warming effect of removing the masking
sulfur dioxide aerosols.
I’ll include quotes to help those who want to follow this up further to see which part I’m referring to:
“C.1.2.
Modelled pathways that limit global warming to 1.5°C with no or limited
overshoot involve deep reductions in emissions of methane and black
carbon (35% or more of both by 2050 relative to 2010). These pathways
also reduce most of the cooling aerosols, which partially offsets
mitigation effects for two to three decades. Non-CO2 emissions can be
reduced as a result of broad mitigation measures in the energy sector.
In addition, targeted non-CO2 mitigation measures can reduce nitrous
oxide and methane from agriculture, methane from the waste sector, some
sources of black carbon, and hydrofluorocarbons. High bioenergy demand
can increase emissions of nitrous oxide in some 1.5°C pathways,
highlighting the importance of appropriate management approaches.
Improved air quality resulting from projected reductions in many non-CO2
emissions provide direct and immediate population health benefits in
all 1.5°C model pathways”
Emissions pathways from Summary for Policy Makers
There may be a “baked in” warming, but if so, it is likely to be less than half a degree.
You can download the chapters from this page: Download Chapters
From chapter 1 Executive summary
Past
emissions alone are unlikely to raise global-mean temperature to 1.5°C
above pre-industrial levels (medium confidence), but past emissions do
commit to other changes, such as further sea level rise (high
confidence). If all anthropogenic emissions (including
aerosol-related) were reduced to zero immediately, any further warming
beyond the 1°C already experienced would likely be less than 0.5°C over
the next two to three decades (high confidence), and likely less than
0.5°C on a century time scale (medium confidence), due to the opposing
effects of different climate processes and drivers. A warming greater
than 1.5°C is therefore not geophysically unavoidable: whether it will
occur depends on future rates of emission reductions. (page 51)
This is very hard to study, there may even be no effect. From Chapter 2.2.1.1 Geophysical uncertainties: non-CO2 forcing agents
The
total aerosol effective radiative forcing change in stringent
mitigation pathways is expected to be dominated by the effects from the
phase-out of SO2, although the magnitude of this aerosol-warming depends
on how much of the present-day aerosol cooling is attributable to SO2,
particularly the cooling associated with aerosol–cloud interaction (page
101)
HOW MUCH CO2 IS TAKEN UP NATURALLY BY THE OCEAN, LAND ETC?
We
do have a fair bit of help here from nature. The oceans and land are
constantly absorbing CO2 from the atmosphere, in addition to the
seasonal cycles. Only 40% or so of the anthropogenic emissions remain in
the atmosphere, and this will continue once we stop emissions. From
the: Global Carbon Budget 2018 (Journal Article), this is a summary of their findings, showing the historical change of the yearly emissions and absorptions
For the last decade, 2008 - 2017, then they work out
- Fossil fuels: 9.4±0.5 gigatons per year
- Land use change: 1.5±0.7 gigatons per year
Total around 10.9 gigatons per year
- Remains in atmosphere: 4.7±0.02 gigatons per year (43.1%)
- Ocean sink 2.4±0.5 gigatons per year (22%)
- Land sink 3.2±0.8 gigatons per year (29.4%)
(result of CO2 fertilization, and lengthening of growing season in northern temperate and boreal (polar) regions). - Budget imbalance 0.5 gigatons per year (4.6%)
(result of overestimating emissions or underestimated sinks)
(note, the numbers may not add up to 100% due to rounding errors)
This
is another recent article, March 2019. It says 31% of anthropogenic
emissions emitted between 1994 and 2007 have been absorbed in the
oceans. Whether it continues to do this depends on the CO2 concentration
in the atmosphere and whether the surface layers of the sea are
saturated (as most of the CO2 doesn’t get any deeper than 1000 meters
from the surface.
It
also depends on the ocean temperature, currents and other details of
multi-decadal oscillations n the oceans. They found for instance that
the CO2 absorption in the Northern Atlantic has decreased recently but
increased in the Southern Atlantic.
This
percentage of CO2 taken up by the oceans has remained relatively stable
compared to the preceding 200 years, but the absolute quantity has
increased substantially. This is because as long as the atmospheric
concentration of CO2 rises, the oceanic sink strengthens more or less
proportionally: the more CO2 is in the atmosphere, the more is absorbed
by the oceans – until it becomes eventually saturated.
So
far, that point has not been reached. “Over the examined period, the
global ocean continued to take up anthropogenic CO2 at a rate that is
congruent with the increase of atmospheric CO2 ,” Gruber explains."
Ocean sink for man-made CO2 measured
ARCTIC WARMING
The
Arctic is the most vulnerable to heating. But the UN report that said 5
°C is already locked in was a mistake, a typo, it should have said 0.5
°C.
If we keep to
the Paris target of 2 °C then the warming is 0.5 to 5 °C in the Arctic
region by the 2080s above the temperatures relative to 1986 to 2005 as
the baseline
RCP2.6
climate-model runs from CMIP5 for the region between 60N and 90N for
the winter months (December, January and February) for the 32 different
climate models providing RCP2.6 runs (with one run used per model).
Model data obtained from KNMI Climate Explorer. Factcheck: Is 3-5C of Arctic warming now ‘locked in’? | Carbon Brief
And this shows what happens to Arctic warming with all the scenarios
IDEA THAT THE WORLD WILL GET TOO HOT FOR HUMANS
Even
a 12 °C rise is not remotely apocalyptic. Earth right now is warmer
than it was during the ice ages but on a larger timescale it’s the
coldest it has been for 450 million years.
Usually
there is no ice at either pole The water at the poles can reach
temperatures of up to 10 C. Even the worst of the climate change
predictions come nowhere close to that. We will have ice in Antarctica
for centuries, probably thousands of years into the future.
At
times in the geologically recent past the world has been so hot that
there were palm trees as far north as the Arctic circle, no ice at
either pole and typical polar temperatures 10 °C.
Phanerozoic Climate Change
500
million years of climate change. As you can see, on the timescale of
millions of years. Earth has never been this cold for the last 450
million years. In this diagram, one part per thousand of oxygen 18
corresponds to around 1.5 - 2 °C
Most
of the time Earth has no ice at all at its poles, no permanent ice at
all except at the top of high mountains. Compared to that, the Earth is
unusually cold at present. We are in the middle of an interglacial but
geologists would say we are in the middle of an ice age still,
technically, since we have permanent ice at the poles.
The
worst case with “business as usual” which we are not headed for is mass
migration of humans from the hotter parts of the world such as the
Persian gulf and the hottest regions of India, not mass extinction.
Parts of Northern India of course are very cold near the foothills of
the Himalayas and they will not get too hot for humans even on the very
worst scenarios. We aren’t headed for a future where Nepal, Bhutan or
Tibet will be too hot for humans on any scenario. Or Ladakh or Gangtok
in India.
This
is a map from a paper that studied the northern Chinese plain, where
many farmers grow rice and work out of doors. It’s especially vulnerable
because of the humidity. Even then the climate is fine for the rice.
The problem is the effect on humans working in the fields.
The graph is here Nature Communications
The
red means business as usual RCP 8.5, the blue is RCP 4.5 approximately
what we are on so far with the Paris pledges and unconditional
commitments, and the black is historical. The graphs are histograms
showing the predicted number of days with at least 6 hours of maximum
wet bulb temperatures for each bin in the thirty years time period from
2070 to 2100 in each scenario.
Over 35 °C then even the fittest farmers would not survive six hours of working in the fields. Work would have to stop.
They focused particularly on China but looked at two other study regions, India and the Persian gulf.
The
dark red areas have wet bulb temperatures over 31 C for 5% of the time,
and risk 35 C heat waves. You can see how it affects eastern China
(above Taiwan in the map) also the coasts of the Persian gulf (but not
the desert interior because it is so dry there) and Bangladesh, Kolkata
and parts of Pakistan.
The figure is here Nature Communications
(with link back to the article page).
For other parts of the world we can go to another study here
This
time it shows the yearly probability of a heat wave that has
temperatures over 55 C. Whether that has a high wet bulb temperature
would depend on the humidity, and you can get conditions too hot in very
damp conditions below that temperature. So it’s not as precise but you
can see that other areas that need attention would include southern US
and northern Australia, and central regions of southern America. Orange
means temperatures over 55 C are experienced roughly every other year.
Paper here
So it does become an issue for some people already at 4 °C.
See my
CLIMATE CHANGE USUALLY MEANS A CHANGE TO A CLIMATE SOMEONE ELSE ALREADY HAS
in
the worst case, which we are not headed for, the UK becomes like Spain.
Well, people have been living in Spain for thousands of years. We
aren’t going to die because we have Spanish temperatures here.
We are not headed for this scenario, nothing like it, with existing policies only a 3 °C rise. But if it gets 10 °C warmer, Aberdeen (14 °C) becomes like Barcelona (24 °C) and Barcelona like Dehli (34 °C) .
The worst outcome is that we end up growing oranges and bananas in the
UK, not that the UK becomes too hot for humans or that we can’t grow
crops at all here anymore.
We
will need to adapt, sure. Right now people in England die during a 30
°C heat wave that would be just normal in a Spanish summer. We don’t
even have air conditioning in most UK houses. We need to get used to
needing it, if the world gets as warm as that.
But for most of us, then other people already know how to live in those conditions and we can learn from them.
Some
people in the very hottest parts of China, India, Persian gulf, United
States and others, especially in hot wet places will find it gets too
hot to survive at all without air conditioning. But this only happens at
a global rise above 4 °C.
It’s
not the heat that gets you, but combination of moist air and heat. You
can keep cool by sweating, but above around 35 °C if the air has 100%
humidity almost nobody can survive. You’ll die within a few hours if you
can’t get somewhere drier or colder. Above 37 °C with 100% humidity,
then that is above blood temperature and your body no longer can cool
itself even slightly and you soon are dead.
But
you can survive by either cooling the air down or drying it out. Even
in a world like that, people with enough confidence in technology could
ride out the hottest heat waves in India, China etc, and of course many
plants would be fine, you could still grow rice, maybe largely automated
cultivation, and crops that like really hot conditions.
It
would certainly have lots of climate migrants. But even in India or
China, to different parts of the same country. The north of India, the
foothills of the Himalayas are pleasantly cool and eventually really
cold. Same for China, and nearly all of Tibet, Mongolia etc.
Meanwhile
Canada, Russia, especially Alaska and Siberia would become warm “des
res” places for humans. They would begin to be places where you can use
conventional agriculture in fields.
If it gets 10 °C warmer, Aberdeen (14 °C) becomes like Barcelona (24 °C) and Barcelona like Delhi (34 °C) .
The
worst outcome is that we end up growing oranges and bananas out of
doors in the UK, mangoes, sugar cane and avocados in France, and perhaps
coconuts in the Mediterranean
Coconut distribution
Might this be a familiar Mediterranean sight in a warming world?
The Lone Coconut Tree , Kannur, Kerala, India. Prof. Mohamed Shareef from Mysore
Cocos nucifera
Blog post here about someone who managed to grow a coconut palm tree in Southern Italy
Farmers
may have to grow new crops. There’s also though research into making
the crops they already use more heat tolerant. This is research into
finding heat tolerant beans that can grow with night time temperatures
as high as 23 °C about 4 °C higher.
CLIMATE ANALOGUES FOR 2080 FOR US CITIES
This
is a project for US cities only, sadly. But it finds climate analogues
in a warming world. For instance if you live in Washington DC, their map
can help you find a city with climate similar to what you will
experience in 2080.
The
top map is RCP 4.5, which reaches 2.4 C by 2100 and the bottom map is
RCP 8.5, roughly equivalent to 4.9 °C. We are currently between the two
headed for about 3 C by 2100
The map shows what the climate is expected to be like by 2080:
A
paler yellower green means a closer analogue. For the low emissions
scenario they found a good analogue, for the high emissions scenario,
none of them were that good but they pick the best.
To
work out the analogue they used the minimum and maximum temperatures
and the total amount of precipitation (rain, snow etc) for the four
seasons of the year. So a close analogue means the temperature range and
the amount of precipitation is the same for all four seasons. A weaker
analogue means that they are only roughly the same.
You
can explore other cities here, it just shows the closest analogue, for
high emissions is 4.9°C by 2100, and doesn’t tell you how close or far
it is as an analogue, but it gives a rough idea:
For reduced emissions, 2.4°C by 2100:
To explore how the climate changes for other cities in the US go here:
And the paper is here
PARIS PLEDGES SO FAR
Every
year, all the nations involved in the agreement meet to increase their
pledges. So this year expect increased pledges from them. But not
instantly to 1.5 °C. Some are already within 1.5 °C. Some even well
within, right down to 1.2 °C and below. A couple are carbon negative,
Bhutan and Suriname which is hugely carbon negative due to all its forests. Costa Rica should be carbon neutral by the early 2020s.
Amongst
populous countries the biggest population on track to 2 °C already is
India with a population of 1.4 billion. India also has 1.5 °C well
within reach for future pledges.
China
is on track for below 4 °C but it needs a huge ramp up in pledges
needed to get down to 2 °C or 1.5 °C. However it had to build an entire
new industry of renewables to get where it is now, has getting on for
half the installed renewables in the world and is exporting the
technology to other countries - it's been a good business move for them
too. They also planted large forests to offset global warming. The IPCC
report said that all four of its 1.5 °C scenarios required a degree of
afforestation.
This
map shows what temperature rise each country’s pledge corresponds to if
everyone did the same. It's interesting to click around. This is just a
screenshot:
The actual map is here, and you can click on each country to see what it’s pledge amounts to by way of temperature rise: Paris Equity Check | Pledged Warming Map
The
ones that are already close to 1.5 °C include Switzerland 1.6 °C, and
Pakistan 1.2 °C is a good example from a rather populous country.
Many
African countries are at 1.2 °C. Philippines, Peru and Ecuador all 1.2
°C. Guatemala and Costa Rica less than 1.2 °C. Indeed, many of the
poorer countries are leading the way.
Remember
this is just the first of many yearly meetings. It's always been the
plan that you have to start somewhere and they will do new more
ambitious pledges.
Nor
is it just that they increase them occasionally - the plan is to meet
and increase their pledges each year. We don't expect them to reach 1.5
°C this time around
But
in the next few years, they will be trying to increase on their
previous pledges each year and more and more countries to get down to
within 2 °C and then 1.5 °C.
That so many are already well within 1.5 °C - it is quite encouraging if you look at it another way.
India
is the most populous of the countries on track to stay within 2 °C and
with 1.5 °C also well within reach, with just short of 1.4 billion
people, according to Climate Action Tracker
After adopting its final National Electricity Plan (NEP) earlier in 2018, India remains on track to overachieving its “2˚C compatible” rated Paris Agreement NDC climate action targets. Estimates show India could achieve part of its NDC goals—a
40% non-fossil-based power capacity by 2030—more than a decade earlier
than targeted. But a question still remains over the future of coal.
If
it were to abandon plans to build new coal-fired power plants, India
could become a global climate leader with a “1.5˚C compatible” rating.
This is more than feasible: the Draft National Electricity Plan
contained no expansion of coal power after 2022. This scenario is
supported by recent developments such as a 50% decrease in the cost of
solar power in just two years and several utilities shelving plans for
building coal plants. In 2017, renewable energy investment topped that
of fossil fuel-related power investments. If the price of solar PV
continues to fall, it stands to become the preferred choice for
distribution companies. However, the final NEP took a backwards step of
including more than 90 GW of planned coal-fired capacity—and these risk
becoming stranded assets.
It
is a particular challenge for China because it is rapidly
industrializing but it is already on track to stay below 4 °C mainly due
to its rapidly growing renewables industry, now amounting to nearly
half the installed renewables in the world, with some of the largest
solar power plants in the world. This is helping their economy too, as
they are exporting the technology to other countries.
They
are not on track for 2 °C. But they are a climate action leader in the
world - it's like trying to reverse the direction of an oil tanker. They
have tremendous momentum and it is a big thing just to stop, and then
they have to reverse. The news reports often don't make this clear. It
was never an expectation of the Paris agreement that the world could
achieve pledges for 2 °C right away. The ones with the biggest
challenges like China have to build up experience and capabilities first
and entire new industries, before they have the ability to make the
stronger pledges needed to stay within 2 °C and then 1.5 °C. The first
thing is to stop the year on year emissions from increasing, and China
is the key to that. Then they have to be reduced.
This is what Climate Action Tracker say about China:
China
is positioning itself as a global climate leader, and its actions have
an enormous impact on global greenhouse gas emissions. Discouragingly, a
rise in coal consumption drove Chinese CO2 emissions to a new high in 2017, which will likely be exceeded again in 2018.
...
The world’s largest emitter, China is simultaneously, and almost
paradoxically, the largest consumer of coal and the largest solar
technology manufacturer, and the choice it makes between the technology
of the past versus the future will have a lasting effect on the world’s
ability to limit warming to 1.5°C. China’s emissions, like the rest of
the world’s, need to peak imminently, and then decline rapidly.
With
current policies, CO2 emissions in China may level off in the next few
years, but total greenhouse gas emissions are projected to rise until at
least 2030.
Even so, China is on track to meet or exceed its 2030 Nationally Determined Contribution (NDC) , which the CAT rates “Highly insufficient.”
...
Under current policies, China is also likely to achieve its (more
stringent) 2020 target to limit fossil fuels, but neither of these
targets are compatible with limiting global temperature increase to
1.5°C.
Given that
China is on track to achieve or overachieve its climate targets, its
next step as a global climate leader could be to set an example by
submitting a strengthened NDC to the Paris Agreement by 2020. (For
details on China’s NDC, see “pledges and targets” section)
YES WE CAN FEED EVERYONE
Some of the scary stories suggest that we won’t be able to feed everyone so I’d like to answer that first.
Food
security is growing year on year. Most of the population increase is in
Africa where the population is projected to increase fourfold from 1 - 4
billion, and the green revolution in the 1950s to 70s which saved
billions from starvation with new methods of agriculture and improved
varieties passed it by.
The US and China produce ten times the yields of crops from the same land area as Sub Saharan Africa.
Yields and Land Use in Agriculture
We
also have a huge safety margin from meat eating. Although it is not
likely to come to it, if the US and Brazil were to switch from growing
feed crops for animals to growing crops for humans from the same ground,
they alone could feed an extra 2.5 billion people (they are both beef
cattle countries and grow a lot of crops just to feed to cows).
The worst case when it comes to feeding everyone is we have to go on rations as in WWII rationed to a few ounces of meat a week.
We
could also feed twenty times as many people than even the most
efficient crop growing in the US using the methods of space agriculture -
fast turn around crops, hydroponics and artificial lighting.
So,
no, nothing we can do can get us into a situation where it is
impossible to feed everyone. But we are not likely to need to use
rationing or biointensive agriculture or space agriculture. Projections
suggest we can feed everyone with conventional agriculture, but it needs
major improvements in crop yields in Africa to do that. And we can do
that with the methods of the green revolution and reversing
desertification.
For more on this see my
WHAT ABOUT SOIL EROSION?
There is a lot of hyperbole again in journalistic stories about soil erosion.
Yes,
there are problems with soil degradation but only in some parts of the
world. For instance there is no soil degradation where I live, the Isle
of Mull off the West coast of Scotland. The soil is growing not washing
away and we are not talking about a future where there won’t be any soil
in the UK. There are many places in the world where soils are growing
(as is the normal situation) just as they are where I live.
There
are some areas where it is a serious issue, especially in Africa,
though there are some problems of soil erosion in most countries
worldwide (even in the UK there are some places where there are issues
of soil erosion) - and many measures are being put in place to stop soil
erosion.
It is an
important matter that needs to be addressed. It’s an essential part of
food security, and also it makes a significant difference to global
warming as a CO2 sink.
This is a symposium to be held in May
This is the FAO overview with various documents you can download
This is the 2015 summary
This is about a new program launched in 2018 to help with the situation in Africa
Soils
are also relevant to climate change, a healthy soil takes up a lot of
carbon and soil erosion leads to emissions of carbon into the atmosphere
WHAT ABOUT THE CLOUDLESS SKIES STUDY?
This
research found that if the CO2 levels got very high, this disspiates
low clouds that form over sea and help to cool Earth down. When that
happens then the temperature worldwide rather rapidly increases by 10
°C. This was rather a surprising result. But we are nowhere near that
threshold.
Their
model suggests that if we continued “business as usual” i.e. if we had
never done the Paris agreement but just pressed ahead regardless, we’d
reach those levels towards the end of this century. But they go on to
say that their model depends on a simplification of the real situation.
In actuality it most likely wouldn’t happen into quite a long way into
the next century even with “business as usual”.
It
is not a risk for us on our current path. But it helps understand why
the Earth got rather hotter at times in the past than you’d expect from
the levels of CO2.
What did the research about “cloudless skies” really show? by Robert Walker on Debunking Doomsday
NO WE ARE NOT IN THE MIDDLE OF A MASS EXTINCTION AND IT CAN’T GO ALL THE WAY TO A TOTAL COLLAPSE
Yes
we are getting extinctions at a far higher rate than normal. But it is
nowhere near a mass extinction yet. Just the start of a slide towards
one that may play out towards the end of this century and in the 22nd
century. Also we are not risking a major mass extinction like the
Permian / Triassic one. The word “mass extinction” does not have a well
defined threshold but I think many who read these stories think it means
that there would be almost no animals, fish, trees, plants or insects
left or hardly any. No it doesn’t mean that. It means fewer species of
each but not a world without them.
Also
we start with a much more varied collection of species than normal
because the continents are spread out on different land masses with
entire ecosystems only in Australia or only in South America or Africa.
When they mix then some species go extinct but the mixed ecosystem ends
up if anything often more diverse than they were before the
introductions.
Also
there is no way that our domesticated animals and plants will go
extinct. We are not headed for a world without sheep, cats, dogs, honey
bees, or fish. We could keep all those things even in space colonies
without any ecosystems at all. We have seed banks and the seeds in those
banks won’t go extinct either.
We also have an additional seed bank at Svalbard as an extra backup of all the world’s agricultural crops
Svalbard Global Seed Vault - Crop Trust
The
seeds are preserved at -18 C. It is buried deep in the permafrost. If
the power failed it would go up to - 8 or - 7 C after a few years, but
even at that temperature most of the seeds would be viable for 20 to 30
years so you have lots of time to decide what to do if power doesn’t get
restored. So it is a safe place for the world’s seeds.
There
are seeds there to restore the world’s agriculture even if there were
no other seeds left in the entire world. Not just the main crops but
numerous wild varieties for each one. Our seed crops are not going to go
extinct.
There
are a few seeds that can’t be preserved like that, some tropical fruits
such as mangos can’t be freeze dried and have to be grown every year.
Only
the corals are at risk of actual destruction of an entire ecosystem. We
are losing species but we are also preserving many habitats and
species.
And we
are saving many of the large iconic species too, we are losing some such
as the northern white rhino sub species, may or may not be possible to
save the species, but e.g. we have saved the whales and there is no
immediate near future of the blue whale going extinct. There would have
been if we hadn't acted. We have saved many other species that would be
extinct already if it weren’t for the work we do to preserve them.
The
extinction rate is higher than background but many ecosystems are
actually becoming more diverse due to incoming species from other
continents, meanwhile worldwide many countries are doing a lot to
protect biodiversity.
The
coral reefs are important for the fish and other creatures that depend
on them. There are many other shallow water ecosystems in the sea. I
cover a couple of the others here:
Yes kelp and seagrass also have issues like coral bleaching - but only vulnerable spots near the warm edge of the species range
More on the coral reefs later in this page, see ACIDIFICATION OF THE OCEANS - WINNERS AND LOSERS
Kelp
and seagrass would not be affected by the coral reefs in any way. They
are independent systems and they do have vulnerable spots but only some
places.
And we are doing lots to encourage and preserve biodiversity. We can and should do a lot more, but are already doing a lot.
You
also get extinctions if you merge together two ecosystems that evolved
separately. For instance, 54 million years from now Australia will crash
into China.
From this video:
That
would mix together Australian and Chinese species that had never
encountered each other before (if it weren't for humans that is) - so
that would then lead to many extinctions. But the resulting ecosystem
would likely be richer than the separate ones are now.
One
interesting biologist, Chris Thomas, as I say in my debunk, argues that
this is a good analogy to most of what is going on right now. A similar
thing is happening in our world to what happens when continents merge,
except we are doing the merging by moving things about across the sea.
I go into this in more detail here
NOT HEADED FOR A WORLD WITHOUT INSECTS
This
was a really low quality survey that hit the headlines. It was not
systematic at all, for instance for the whole of China they only had one
data point, for domestic honey bees! And they found the studies by
searching for articles with “Declin*” in the subject line.
We
Are NOT Headed For World Without Insects - Insect Decline Survey
Hitting Headlines Non Systematic, Patchy & With Limited Data
There
was a much better report from the UN just a week or two later and they
did find that crops are better pollinated if there are wild insects as
well as the domesticated honey bees, and that if there are more
pollinators the crop yields increase (obviously only for crops that
require pollinators)..
They
comment that climate changes would require pollinators to shift their
geographic zones and that some species might struggle to do that with
sufficient speed. And talk about how preserving pollinator diversity can
help in a buffering role, meaning those effects are less significant
for crops.
So yes, diversity of pollinators is important.
Later
on in the section 4.3.4 Associated biodiversity for pollination they
talk about insects in detail. They talk about some individual reports.
They mention the German study, which I covered before here:
They
also mention that Germany has started an Action Program for Insect
Protection which is here (you can use google translate to see it in
English): Insektenschutz
In
their review of insect trends then it was mixed - most habitats had
both rising and decreasing populations reported except for grasslands
grazed with livestock which did show a downward trend. This was a far
more systematic review than that appalling study a week or two
previously. Yet it didn't feature on the news at all, while the other
one had interviews with the researchers who said ridiculous things such
as that we are headed for a world without insects which simply makes no
sense at all.
I
did an article about the UN biodiversity report here and it is worth
dipping into the full report as it has many case study stories and some
are rather heartening - gives an idea of how much is being done
worldwide to preserve biodiversity.
They
found that insects were decreasing only on livestock grassland-based
systems. Everywhere else, the countries reported stable or mixed trends
(i.e. neither increasing, nor decreasing nor stable trends predominate).
The
main causes of decline identified by the countries were pesticides,
human induced habitat loss, fragmentation, and climate change. Amongst
those reporting increasing trends were Nepal due to crop
diversification, several European countries due to flower strips in and
around fields (as a result of an agri-environmental scheme) and
increases in forest area particularly planted forests. While logging,
natural disasters such as hurricanes, invasive species, overgrazing in
Argentina and undergrazing in Norway all were thought to have caused
declines in numbers of pollinators. See the section ''Status and trends
of pollination" on page 134.
They
remark on the limited data for insects, but it is vastly better than
that insects study that hit the news a week or so back.
They
talk about many measures that countries are taking to help support
pollination of their crops. For instance they cover Malaysia’s
“stingless bees” project. These are a different species from honey bees
that are adapted to tropical and subtropical species and are better able
to pollinate their crops than traditional honey bees. And they do also
produce honey. Stingless Bees - Facts, Information & Pictures
The government has promoted keeping of stingless bee colonies to help with pollination:
There
are many more details there in the report about the many things
countries worldwide are doing to encourage biodiversity. As well as UN
recommendations of ways that they will be able to do more of this in the
future.
If you
read the report itself it is far from bleak and rather heartening to
read about all these projects so many countries are involved in to
protect biodiversity.
They
talk about many countries who submitted reports to the UN on measures
they are taking to ensure biodiversity as part of their food and
agriculture policies. This table is from 5.2 Overview of management
practices and approaches
Though
only some of the countries submitted reports they all reported
increasing trends for nearly all these measures to promote and protect
biodiversity.
The
report is reasonably optimistic about the future. Many countries
implementing such practices for crops, but having problems getting them
in place that need to be addressed. The report itself has identified
many knowledge gaps and actions they need to take in the future.
This is their conclusion of the report:
Positive
global developments include, on the one hand, growing awareness
internationally of threats to the sustainability of food and
agriculture, including those related to the loss of biodiversity, and on
the other, upward trends in levels of adoption of various management
practices that potentially contribute to the conservation and
sustainable use of BFA. These developments need to be built upon by the
global community. Knowledge gaps need to be filled, cooperation
strengthened, including cross sectorally and internationally, and
financial, human and technical resources mobilized. Effective legal and
policy frameworks need to be put in place. The country-driven process of
preparing The State of the World’s Biodiversity for Food and
Agriculture has led to the identification of numerous gaps, needs and
potential actions in the management of BFA. The next step is to take
action. Over the years, the Commission on Genetic Resources for Food and
Agriculture has overseen the development of global plans of action for
genetic resources in the plant, animal and forest sectors.
Implementation of these instruments needs to be stepped up.
Consideration also needs to be given to how the international community
can more effectively promote synergies in the management of all
components of biodiversity, across these sectors and others, in the
interests of a more sustainable food and agriculture.
The State of the World’s Biodiversity for Food and Agriculture 2019
More about it in my article here:
COST TO THE ECONOMY OF BILLIONS, BUT SAVING TRILLIONS
You
often get articles saying we can’t do these things to curb CO2
emissions, because it is too expensive - so let’s look at that.
This
study finds that indeed it is more expensive to stay within 2 °C than 3
°C and that 1.5 °C is more expensive than either. But the costs are not
that high compared to other things we spend money on.
They
estimate a total cost to the world economy of the unconditional NDC’s
as $135 billion by 2030, if they assume conditions of slow economic
growth, rapid population growth and high inequality.
It’s less than half of that however, if they make more sustainable socio-economic assumptions.
The
conditional pledges that various of the developing countries have made
where they pledge something dependent on financial help from wealthier
countries amount to a total of $40 to $55 billion .
That’s
for the 3 °C path we are already on. For 2 °C they estimate the cost as
at least three times higher and for 1.5 °C, it’s 5–6 times higher.
However while spending tens of billions we are saving trillions:
Also
even these costs are not that large compared to, for instance, the
estimated cost of renewing the UK Trident submarine. According to CND it
may be as much as over £200 billion
And modernizing and maintaining the US nuclear arsenal over the next 30 years will cost $1.2 trillion according to one estimate.
If we can afford nuclear weapons surely we can afford to pay for climate change mitigation.
And
at the same time save us lots of money for the future so that we end up
3% wealthier in 2100, or about $30 trillion dollars better off than if
we hadn’t done it according to that paper.
It seems a no brainer really.
It’s
more a matter of how to find a way to get from here to there. If it is
going to benefit us so much as a world economy, can we do it in a way
that the benefits are linked close enough to the costs to circle around
and feed back into the process?
There is another figure you see though, from the IPCC report in 2018. The summary for policy makers says that we will need to invest around $2.4 trillion extra in the energy sector. That may seem daunting at first:
“Global
model pathways limiting global warming to 1.5°C are projected to
involve the annual average investment needs in the energy system of
around 2.4 trillion USD2010 between 2016 and 2035, representing about
2.5% of the world GDP (medium confidence).” 4.4.5, Box 4.8}
This
is not quite the same thing though. It is investment for a return on
the investment. This is a modest increase in investments we already do.
It is explained in detail in chapter 4.4.5
The
average increase of investment in the energy sector resulting from Box
4.8 represents a mean value of 1.5% of the total world investment
compared with the baselines scenario in MER and a little over 1% in PPP.
Including infrastructure investments would raise this to 2.5% and 1.7%
respectively.
In
other words we have to invest an extra 1.5% in the energy sector every
year, over what we are doing at present. Or 2.5% including the
infrastructure investments.
Meanwhile
the fossil fuel assets we have already are decreasing in value. So it’s
a case of investing more in green energy at the same time as fossil
fuel assets decrease in value.
They say in their box 4.8
“
Part of the challenge may lie in increasing the pace of financing of
low-emission assets to compensate for a possible 38% decrease, by 2035,
in the value of fossil fuel assets (energy sector and indirect holdings
in downstream uses like automobiles) (Mercure et al., 2018).”
Much
of their chapter 4 is about how this might be achieved. It’s complex
economics and I’m no economist but they clearly think it can be done.
GWP100 OR GWP10
What does this mean?
It
doesn't make any difference to the predicted temperature changes as
they don't use GWP100 for the modeling but directly model the effects of
the methane. In their models they have as input the methane emissions
for each year, and then they work out the temperatures from those
directly by looking at the effects of that methane on the climate.
It
makes a difference rather to policies, if you use GWP10 then countries
that do rapid reductions in methane while keeping CO2 levels high will
be seen as contributing more towards climate change mitigation in their
NDC's.
It also
changes the way you present the model. If you ask "for this model with
these assumptions about methane emissions, when are net zero emissions
achieved" then the time of net zero CO2 emissions is moved forwards but
only by a few years on most of the scenarios. This makes no difference
again to what happens to the temperature, to how the models respond to
the emission changes, but the point at which you say to policy makers:
"We have reached net zero" changes.
This
is especially significant for policy if you do negative CO2 emissions
to keep at net zero and target net zero emissions for the second half of
the century. Whether you use GWP100 or GWP10 will change the targets of
how much negative CO2 emissions you need to do.
If
you target net 0 with GWP10 then you focus more on reducing methane to
start with, so that then means a different projection with more rapid
temperature effects early on. Use of GWP100 for net zero emissions comes
closest to holding temperatures constant by maintaining net zero
emissions.
The
higher metric value for methane under GWP20 or GTP100 (another metric,
based on temperature rather than warming potential but harder to
calculate)) means you need to use more negative CO2 emissions to achieve
a perceived net zero emissions and so you get a higher offset and so
the temperatures actually decrease significantly within a few decades
under a net zero with GWP20 would be even more with GWP10.
With this background, if your aim is to reach a steady temperature after net zero emissions use of GWP100 makes more sense.
If you want to come back to a lower temperature at that point use of GWP10 or GTP100 would make more sense.
This
graph shows the difference, these are years after net zero emissions
are achieved, they assume in the year 2100 and assume policies from then
on maintain exactly net zero with the GWP100, GWP20 or GWP* a new
metric the author proposes and various GTPs.
The
GWP20 is in black and results in a net drop by over 0.7 C in a century.
The GWP100 is in orange and results in a drop of nearly 0.4 C in a
century both assuming you use those metrics as a basis for your policy
of net zero emissions. It's of course using many different assumptions
about the amount of methane emitted etc, the solid lines are an average.
The
GWP* is a new metric proposed by the authors, which results in more or
less constant temperature if you target net zero emissions using that
metric. That's figure 5a from this paper from 2018
Implications of possible interpretations of ‘greenhouse gas balance’ in the Paris Agreement
WHAT HAPPENS AFTER 2100?
Let’s look at a longer time period beyond 2100.
I already shared this graph but let’s share it again:
Topic 2: Future changes, risks and impacts
In
this figure the blue line is the one that goes down to zero emissions
quickly. It levels off at 1.5 °C above pre-industrial and then slowly
goes down after that getting back to our current levels by a little
after 2300. The red curve is “business as usual” in which emissions stay
constant through to 2150 and after that CO2 concentrations stay
constant (the rationale being there just aren’t enough resources
available to keep burning fossil fuel endlessly):
The RCP greenhouse gas concentrations and their extensions from 1765 to 2300
Even
that red graph will not make Earth uninhabitable to humans. There will
still be ice at both poles, with the Antarctic and Greenland ice taking
thousands of years to melt. And as the world warms up then parts of
Siberia and Canada open up to conventional agriculture.
It
is much more a case of climate migration, of people moving from one
part of the world to another. We could feed as many people. There is a
lot of leeway here. With biointensive agriculture we could feed ten
times as many people and with space agriculture methods using mainly
crops with a very rapid turnaround time of 30 days and hydroponics /
aeroponics and artificial lighting you can feed a hundred people from an
acre ,which under conventional agriculture can only feed one person.
But
we don’t need that even. There is a lot of improvement possible with
inefficient agriculture especially in Africa which has missed the green
revolution that saved billions from starvation in the 2050s to 70s. For
more on this see my
However,
I think we can forget about “business as usual” since we are not on
that pathway. So I won’t go into this any more here.
WHAT ABOUT OUR POPULATION AFTER 2100
The
world population is set to level off by 2100 and most of the rise in
population is in Africa. Due to prosperity rather than scarcity.
It’s
the most prosperous countries that have declining populations, such as
Japan. Our population is leveling off due to prosperity rather than
scarcity.
We
reached close to peak child about a decade ago, number of children is
still slightly increasing year on year but hardly at all, most of the
increase is due to a dramatic increase in life expectancy, by 20 years
in the last half century in the developing world and by ten years in the
developed world. In some places it’s even more, 30 years.
Life expectancy is increasing for all age groups, most for the younger children and newborns - this is for England and Wales:
Although
it is a challenge to feed another four billion people we can definitely
do it. We could in worst case do it just by rationing meat in the more
developed countries, but it is not likely that it comes to that. And the
population may well level off before then, Africa is the key, a
four-fold increase in its population is a big increase and it may not
happen if they can move to prosperity and higher levels of education
sooner. Whether our world population in 2100 is well over or well under
ten billion mainly depends on what happens in Africa.
What
will make the difference is not scarcity but the opposite, improvements
in education of women, their opportunities in the job market and the
pace of improvements in child health.
The
UN projects a population [in Africa] of 4.5 billion while WC-IIASA
projects a population of only 2.6 billion. This difference of 2 billion
is just as large as the difference between the projection for the global
population by the UN (11.2 billion in 2100) and WC-IIASA (8.9 billion
in 2100). Whether the world population increases to more than 10 billion
will be decided by the speed with which Africa develops – especially
how quickly women get access to better education, women's opportunities
within the job market, and how rapidly the improvements in child health
continue.
When will the world reach 'peak child'?
For more on this:
WHAT ABOUT THE MELTING ICE?
Well
eventually, with "business as usual", the Greenland ice sheet is likely
to melt completely leading to a sea level rise of 7 meters average, and
much higher in some parts of the world. The threshold for this to
happen is probably less than 4 C relative to pre-industrial and it may happen even with a 1 C rise. But this is likely to take a thousand years (it takes a long time to melt all that ice).
What about the nearer future, in the 22nd century?
In these new studies,
a team of glaciologists using satellite and air measurements say that
the ice in Western Antarctica has already started a process that is
probably impossible to stop. With ice penetrating satellite radar
mapping of the terrain beneath the ice (using the EU Sentinel 1 satellites),
they say that here are no mountains or hills significant enough to slow
the collapse. The fastest melting glacier, Smith glacier, is losing 70 meters thickness of ice a year. It's grounding line - the point at which it starts to float on the sea - is retreating two kilometers a year and has been doing that since 2011, is continuing unabated.
There
are six glaciers that will collapse, enough to raise the sea level
another four feet. But these may collapse other glacier leading to a
rise of sea levels triple that. A separate team studying just one of the
glaciers, Thwaite glacier, came to the same conclusion that collapse is
inevitable. That is, will happen anyway, based on the CO2 emissions so
far.
NEXT ICE AGE - POSTPONED
Our
climate is predictable over such long timescales that they can even
calculate when the next ice age will be - with or without CO2 warming -
different dates for the two cases - though over shorter timescales you
of course still can't predict every heat wave and hurricane.
Usually
an interglacial like ours lasts for only around 10,000 years. It's
11,500 years since the last ice age. The amount of sunshine we receive
in the northerly 65 degrees latitude is close to its minimum for the
Milankovitch cycles. That would normally mean that we would be headed
for an ice age already. But we aren't. Why is that?
In
a recent study the authors selected only the models that most
accurately tracked the previous ice ages, and used that to study whether
or not we are due to plunge into the next ice age. They found that if
they ran the models with CO2 levels of 240 ppm, similar to the Halocene,
then the next ice age would be as soon as 1500 years into the future.
But
if they used the pre-industrial levels of CO2 of 280 ppm, then the next
ice ages should be 50,000 and 90,000 years from now (with a possibility
of a slowly approaching ice age 20,000 years from now). Just that extra
40 ppm made all the difference. They are unsure why we had more CO2
this time around. Perhaps human activity even in pre-industrial society
was enough to raise the levels by 40 ppm, which isn't very much, or at
least contributed to the levels.
They
found that with 500 Gt of emissions, not far off what we have already
reached, we may already have enough CO2 in the atmosphere to make a
difference to the ice sheets over thousands of years. If it reaches 1000
GT then the chance of an ice age in the next 100,000 years is notably
reduced and with 1500 GT of emissions then it is very unlikely that we
get an ice age in the next 100,000 years. And with higher levels of
emissions, then we will end the pattern of ice ages altogether. You can
read it in full under Nature's sharing initiative if you click on the
link " published in the journal Nature" in the article in the Guardian
here: Fossil fuel burning 'postponing next ice age
In that paper, they say
"
Using an ensemble of simulations generated by an Earth system model of
intermediate complexity constrained by palaeoclimatic data, we suggest
that glacial inception was narrowly missed before the beginning of the
Industrial Revolution. The missed inception can be accounted for by the
combined effect of relatively high late-Holocene CO2 concentrations and
the low orbital eccentricity of the Earth7. Additionally, our analysis
suggests that even in the absence of human perturbations no substantial
build-up of ice sheets would occur within the next several thousand
years and that the current interglacial would probably last for another
50,000 years."
So
in other words yes, we were due to go into an ice age around the start
of the industrial Revolution, but it's not just the CO2 that stopped it.
The various cycles are complex with many factors interacting and their
analysis suggests that this time around the interglacial would have
lasted 50,000 years anyway.
Their crucial graph is this one on page 203 of the paper.
The
graph at the top shows the effects of different levels of CO2 now over
the next 100,000 years plus in black, variations in amount of sunlight.
The graph at the bottom shows the amount of ice in red, orange or blue
with the colour there matched to the colour of the curve in the top half
of the graph.
Notice
that there's a significant difference between the predictions of the
amount of ice, depending on the levels we reach in the near future, even
100,000 years from now.
With
all the scenarios, there is much less CO2 of course 100,000 years in
the future, but you still see differences because the amount you have
then if we get to 1000 gigatons this century is still double the amount
you get if we don't go above 500 gigatons. Apparently even that small
amount of CO2 is enough to be significant.
The reason is that the way carbon dioxide behaves in the atmosphere is very complex.
- The
average lifetime of a CO2 molecule is around 4 years in the atmosphere.
But that’s for the more rapid processes such as plant growth, and
absorption in the surface water of the ocean. Much of that gets
circulated back into the atmosphere again.
- The slower cycle of removal of CO2 from the atmosphere is complex and behaves in surprising ways.
(see . CLIMATE CHANGE - the IPCC scientific assessment)
One
of the complexities is that as the CO2 is absorbed in the ocean, the
upper layers get more saturated in CO2 but there isn’t much mixing and
most of the CO2 remains in the top 1000 meters. As CO2 levels go down,
excess CO2 in the water means it dissolves into it less easily.
For instance after adding a pulse of CO2 to the atmosphere,
- Half is removed in 50 years. You might think, half would be removed again in the next 50 years, but no
- It takes 250 years to get down to a quarter of the original concentration.
- Around 15 percent of the original pulse remains in the atmosphere pretty much permanently, for thousands of years
- The long term half life is 35,000 years. Fossil fuel burning 'postponing next ice age'
So for example, of the roughly 32 billion tons of CO2 that humans added to the atmosphere in 2010
- 16 billion tons will still be there 50 years later, in 2060,
- 8 billion tons will still be there 250 years later in 2260
- 4.8 billion tons will still be there indefinitely, for thousands of years.
That
15% which is left after thousands of years with a long term half life
of 13,500 years is enough to prevent the next ice age and possibly,
depending how much CO2 we add in total, end the cycle of ice ages
altogether.
It's
not so bad at all to have prevented the next ice age. The climate is
much more stable during the interglacials, while during ice ages then
you can get dramatic changes of climate within decades. Also the Earth
is more habitable for us during the interglacials.
If
the climate gets too hot then we could be headed for a hothouse Earth.
If it weren’t for the CO2 emissions we’d be headed for a new ice age
eventually thousands of years into the future. As is then so long as we
can stop emissions some time this century we should be headed for a
reasonably comfortable intermediate state, which could keep our climate
stable and comfortable for humans for tens of thousands of years into
the future.
See also my
SEE ALSO
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