- So, Sir David, what's worries you most?
- The Greenland Ice Sheet. If it melts human civilisation is finished.
- oh. And err is it melting?
- Yes, and accelerating.
- Oh.
https://physicstoday.scitation.org/do/10.1063/pt.5.020563/fu...
Yes, an Antarctic melt would be worse, but it's far less likely.
[1]https://ocean.si.edu/through-time/ancient-seas/sea-level-ris...
"Whether it takes another 200 or 2000 years largely depends on how quickly the ice sheets melt. Even if global warming were to stop today, sea level would continue to rise."
-- from the same article (2 sentences later)
7 meter rise over 2 centuries can likely be managed in a reasonable manner via land taxation, resettlement, wall, and levy construction. 7 meter rise in 5 years would likely collapse most of the western world as major population centers find themselves unlivably under water.
What we get is every single existing ocean port city (which is a lot of the largest cities) being threatened by more frequent flooding. They're all right at sea level, because that's where you build port cities. Not all of these cities really depend on being ports any more, but that's how they became major population and business centers.
They don't just pick up and move something like that. There's no place you can say, "Oh, they're going to move New York over to X, so I'll buy land there now". Even if they did for some reason decide that it was so bad they had to abandon New York (or Charleston or San Francisco or lots of others), there's no one place that it goes. The whole human geography of it changes.
Human civilization didn’t, because human civilization didn’t exist at the last glacial maximum, and almost all of that rise was before human civilization existed. Low density nomadic hunter-gatherer existence is less disrupted by sea level change than settled agriculture and industry.
Besides it's climate impact and heat transfer mechanism it will likely disturb the other ocean currents that are import for a stable climate as well.
Easily getting us to the edge of what is livable even with advanced technology.
I'm going to choose to worry about other things.
https://www.carbonbrief.org/new-climate-models-suggest-faste...
Those of you downvoting me to banish your anxiety should find a healthier outlet for your issues.
The only related thing I could find in your linked report was to estimate contributions up by 2.6cm/2.8 cm/5cm (different scenarios) from CMIP5 to CMIP6, not in total. Maybe I missed something?
That carbonbrief article links to the underlying paper at : https://www.nature.com/articles/s41467-020-20011-8
The paper reports on an update of previous studies, and the results are reported mainly as changes from the previous material to reflect the impact that changes in the modelling decisions.
I can't tell where the 2.1 cm to 5 cm numbers come from (searching the paper for "2.1" is interesting).
Here is a table from the paper reported as total sea level impact estimates and 1 stddev range, rather than deltas : https://www.nature.com/articles/s41467-020-20011-8/tables/1
It reports the expected 2100 see level rise from Greenland ice melt of 6 different scenarios, in two methodologies. The low, low stddev at 3.7 cm, and the high, high stddev at 25.6 cm.
And of course sea level may also be rising from other sources, that just isn't covered in the paper you mention.
You get to pick your personal items to worry about based on your individual assumptions and interests, but if your opinion is based in part on that specific paper you might want to reread it.