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knb comments on Open thread, Nov. 02 - Nov. 08, 2015 - Less Wrong Discussion

4 Post author: MrMind 02 November 2015 10:07AM

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Comment author: Panorama 05 November 2015 08:32:15PM 2 points [-]

NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses

A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice.

According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.

“We’re essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica,” said Jay Zwally, a glaciologist with NASA Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study, which was published on Oct. 30 in the Journal of Glaciology. “Our main disagreement is for East Antarctica and the interior of West Antarctica – there, we see an ice gain that exceeds the losses in the other areas.” Zwally added that his team “measured small height changes over large areas, as well as the large changes observed over smaller areas.”

Comment author: knb 06 November 2015 05:02:40AM 1 point [-]

This seems significant, but I'm not sure how to interpret it... Is it good news the ice sheet isn't shrinking or bad news that the sea level rise apparently came from other sources without us noticing?

Comment author: Lumifer 06 November 2015 03:33:58PM 1 point [-]

the sea level rise apparently came from other sources

Which sea level rise?

Comment author: CellBioGuy 07 November 2015 09:57:56PM *  3 points [-]

http://www.worldviewofglobalwarming.org/images11/SeaLevelRiseRateChart2010.jpg

This is the global mean. Rise measured at any given actual shoreline will be different and sometimes even falling, due to local geology altering elevations of land at not-dissimilar rates in some areas (especially areas where post-glacial rebound is still occurring) as well as thermal expansion being uneven.

Comment author: Good_Burning_Plastic 08 November 2015 10:40:02AM 1 point [-]

Was something weird happening in the 1920s or is it just an optical illusion due to the black lines?

Comment author: CellBioGuy 12 November 2015 02:26:38AM 0 points [-]

I think you'd see similar anomalies in 1880 and 1985 stand out with similar lines.

Comment author: Lumifer 08 November 2015 05:32:34AM 0 points [-]

Yes. But the sea levels have been rising continuously since the time of the last glacial maximum. 10,000 years ago they were rising at a rather more dramatic rate, too.

Comment author: CellBioGuy 08 November 2015 09:29:34AM *  1 point [-]

Yep! My favorite bit of what went on during the end of the last glaciation is the way that it happened unevenly, a sedate constant flow of water from ice to the oceans interrupted by centuries here and there where sea level rose by at least 2-5 centimeters a year. Presumably that's what happens once an ice sheet becomes unstable and pieces of them collapse quickly and nonlinearly.

Comment author: Lumifer 09 November 2015 04:19:35PM 1 point [-]

That was one of those "interesting times to live in"? Still it's peanuts compared to the mother of all floods :-)