Oh, just had a look, at r/collapse, yes, they are way over exaggerating. But it does have some interesting links there on climate change. This one caught my eye. Two comments saying "we will all die" but it's not that. It's "just" increased risk of flooding.
This is about the Western Antarctic ice shelf. They say that it could melt in its entirety in 100 years. If so then this would cause a 10 foot rise in sea level. This would cause issues for coastal cities like New York and low lying countries like the Netherlands and Bangladesh which is the area in the world likely to be most affected by sea level rise since much of the country is not far above sea level.
They spotted a new rift which may lead for a large ice sheet to break off again, like the giant 225 square mile "iceberg" of 2015.
Rift in Pine Island Glacier ice shelf, Credit NASA/Nathan Kurtz.They say there that many think it is inevitable that the Western Antarctic ice sheet will disappear. The main Antarctic ice sheet is still growing. Antarctica has been growing steadily all through the glacial and interglacial periods which is why we have these long ice cores to look at the temperature changes in Antarctica in exquisite detail. If we continue "business as usual" it will stop growing and eventually thousands of years into the future, melt completely. But that is not a risk at present. The risk is just from the Western ice sheet. But because the ice rests on land, rather than on the sea, adding this to the oceans will raise the height of the oceans, and they estimate by 10 feet so about 3 meters.
So what effect will it have if they are right? Not end of civilization. But some major issues. Florida is amongst the most affected since the underlying geology is porous limestone. This means it will be impossible to build conventional flood barriers as the sea will just percolate through the rock beneath them. So it seems inevitable that Florida will be flooded if sea levels rise. Only mitigation possible as a way ahead.
Here it is as it is now.
And after a 3 meter rise
It is already getting affected more than usual by hurricanes because of the one foot the sea has risen by so far. See Goodbye Miami for an article in Rolling Stone magazine about these issues.
In the US, then New York is also impacted and other coastal areas. You can have a look with this global sea level rise map, though be aware - that it just maps a new sea level against the topography of google maps. Places that are inland below sea level of course will not experience sea level rises - you need to trace out to see if there is a connection with the sea. But in the case of Florida, since the underlying rock is porous, then the map above probably pretty much shows what the effect would be no matter what flood defenses are used.
World wide then naturally the Netherlands are amongst the most affected. As a rich country they would be able to increase the height of their flood defenses but it would be expensive. Other coastal areas in France, Belgium, Denmark and the UK (e.g. the Norfolk broads) would also be affected.
Here is the area as it is now:
And after a 3 meter rise. Remember only places that are shown as blue and connected to the sea would actually be flooded. Unless the geology is porous, inland areas below sea level would not be affected, and the Netherlands particularly can be expected to build better flood defenses, though a 3 meter increase in height of them would be an expensive undertaking.
Then finally, this shows the effect for Bangladesh of a 3 meter rise. This is likely to be an overwhelming humanitarian issue for a poor country with a huge population and they would surely need external help to deal with the issues.
Bangladesh as it is now
And after a 3 meter sea level rise such as might happen by 2100 if the western Antarctic ice sheet melts
So, no, a ten foot rise in sea level will not mean the end of civilization at all, but major problems for several particularly vulnerable spots world wide.
It's the same for the other predictions, as I explained in this article. We'll survive, we'll get by, but the unanimous political decision by all the countries world wide (at least as long as Obama stays president) is that it is much more sensible to prevent the effects than to mitigate them after the event.