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Climate Central reports
[...] A massive iceberg roughly 225 square miles in size--or in more familiar terms, 10 times the size of Manhattan--broke off [from the Pine Island Glacier] in July 2015. Scientists subsequently spotted cracks in the glacier on a November 2016 flyover. And in January, another iceberg cleaved off the glacier.
Satellite imagery captured the most recent calving event, which Ohio State glaciologist Ian Howat said " is the equivalent of an 'aftershock'" following the July 2015 event. The iceberg was roughly "only" the size of Manhattan, underscoring just how dramatic the other breakups have been.
[...] The ocean under Pine Island Glacier's ice shelf has warmed about 1°F since the 1990s. That's causing the ice shelf to melt and pushing the grounding line--the point where the ice begins to float--back toward land, creating further instability.
[...] The glaciers [such as the Pine Island Glacier] and ice shelves [such as the Larsen C ice shelf, which is on a death watch] help hold back a massive ice sheet on land. Their failure would send that ice to the ocean, pushing sea levels up to 13 feet higher than they are today.
[...] Cutting carbon pollution presents the only path forward to stave off the worst impacts of a melting Antarctic.
(Score: 4, Informative) by butthurt on Sunday February 19 2017, @05:04PM
I question the amount of height the sea level is claimed to change, as the oceans are already a very big place and changing their level is going to require an awful lot of water.
Antarctica is estimated to have 26.5 million cubic kilometres of ice.
http://www.bbc.co.uk/news/science-environment-21692423 [bbc.co.uk]
The area of the world ocean is estimated at 361.9 million square kilometres.
https://ngdc.noaa.gov/mgg/global/etopo1_ocean_volumes.html [noaa.gov]
By simply dividing the volume of ice by the area of the ocean I crudely estimate there could be 73.2 m of sea level rise if all that ice were melted. In actuality it would rise less than that, because some of that ice is already resting on the sea floor and low-lying land would be flooded. When ice that's below sea level melts, it actually causes the sea level to fall a little. The BBC article I linked gives an estimate of 58 m.
The estimate you may be questioning, however, is for the West Antarctic ice sheet only. In Wikipedia someone has written that the West Antarctic ice sheet comprises about 10% of the ice in Antarctica. I wasn't able to confirm the source that's cited because dx.doi.org wasn't working for me.
https://en.wikipedia.org/wiki/West_Antarctic_ice_sheet [wikipedia.org]
https://dx.doi.org/10.1029%2F2000JB900449 [doi.org]
However 13 feet is 4.0 m; that's a fair bit less than 10% of 58 m.
Later in the article is a prediction that melting in "West Antarctica could contribute an additional 8 inches of water" (20 cm) to the ocean "by the end of this century." If that fails to happen, it won't be for lack of enough ice.
(Score: 2) by HiThere on Sunday February 19 2017, @07:45PM
Yes, but it's doubtful that all of Antarctica will melt (not that that was claimed in this article, but I've seen some...).
What I noticed missing in the summary is any estimate of how long it would take the glacier to move out to being an ice-shelf. There probably isn't a decent prediction, but it's worth noting that a few centuries wouldn't really be surprising. (Of course, other things are happening at the same time, and every fractional inch of rise in sea level places more ice on the float, where it can more easily move. So a shorter time-frame also wouldn't surprise me.)
Still, I suspect that "300 foot rise in sea level" as being interpolated by a reporter, unless the original phrase had a whole bunch of qualifiers around it.
This is significant, but it's quite unlikely to be all that significant in and of itself, but only as a part of a much more widespread process.
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(Score: 2) by butthurt on Sunday February 19 2017, @09:00PM
I didn't see a mention of a "300 foot rise in sea level."
(Score: 2) by HiThere on Monday February 20 2017, @02:52AM
You're right. It was a 13 foot rise that I didn't believe (unless the summary has been edited). I feel innumerate.
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