It isn't going to be 20 feet in the next couple of years. But it is coming. Again, Google Pine Island Glacier.
Satellite observations available since the early 1990s provide more accurate sea level data with nearly global coverage. This decade-long satellite altimetry data set shows that since 1993, sea level has been rising at a rate of around 3 mm yr–1, significantly higher than the average during the previous half century. Coastal tide gauge measurements confirm this observation, and indicate that similar rates have occurred in some earlier decades.
oceanservice.noaa.gov
Note: this is from measurements, not a model like you've been claiming.
All projections assume a constant rate of increase. But there are lots of reasons to doubt that always occurs. Core samples from the ocean bottom show that there have been 8 times since the last ice age when a huge number of icebergs were calved off of the glaciers in Antarctica. The biggest was 14600 years ago, and the oceans rose about 13 feet in less than a century. Since ice sheets were still melting in Northern Hemisphere, the thought is that Antarctic melting accounted for about half that rise.
Natural climate warming caused huge ice sheet collapses in Antarctica eight times in the past 20,000 years, according to the study, published today (May 28) in the journal Nature. Measurements at Antarctica's biggest glaciers, such as Thwaites and Pine Island, suggest the ice sheet is on the brink of a similar massive retreat. [ Photos: Antarctica's Pine Island Glacier Cracks]
...
The biggest pulse of debris was 14,600 years ago, at the same time as a global sea-level rise of about 13 feet (4 m) within 100 years, said study co-author Axel Timmermann, a climate scientist at the University of Hawaii at Manoa. Because ice sheets in the Northern Hemisphere were melting at the same time, scientists think Antarctica's melting accounts for about half of this jump in sea level, he said.
livescience.com |
