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We have been underestimating the amounts of sea level rise due to global warming

We may be in for far higher amounts of sea level rise than ever thought before, Mashable, BY ANDREW FREEDMAN, 13 Dec 17, The amount of sea level rise that many of us will experience in our lifetimes may be more than double what was previously anticipated, unless we sharply curtail greenhouse gas emissions, according to a new study that factors in emerging, unsettling research on the tenuous stability of the Antarctic Ice Sheet.

 Importantly, the study highlights that cuts we could still make to greenhouse gas emissions during the next several years would significantly reduce the possibility of a sea level rise calamity after 2050.

Published Wednesday in the open access journal Earth’s Future, the study is the first to pair recently discovered mechanisms that would lead to the sudden collapse of parts of the Antarctic Ice Sheet, such as the disintegration of floating ice shelves and mechanical failure of tall ice cliffs facing the sea. The study also goes a step further by showing how the new projections could play out city by city around the world.

Researchers from several institutions, including Rutgers University, Princeton, Harvard, and the nonprofit research group Climate Central found that sea level rise predictions that incorporate a faster — even sudden — disintegration of huge parts of the Antarctic Ice Sheet would yield far more dire projections.

 This is especially the case when compared to the consensus put forward by the U.N. Intergovernmental Panel on Climate Change (IPCC) in 2014.

The IPCC did not incorporate the possibility that the Antarctic Ice Sheet could become unstable as air and sea temperatures warm, and essentially crumble into the sea, in rapid succession.

 More than 4 feet of sea level rise

Specifically, the new study finds a median sea level rise projection of 4 feet and 9 inches during the 21st Century if greenhouse gas emissions remain on their current high trajectory.

Or, when expressed as a range, the study shows that a high emissions scenario that takes new Antarctic melt mechanisms into account would yield between 3 and 8 feet of global average sea level rise by the year 2100. This contrasts with the projection that does not include the rapid Antarctic melt mechanisms, which shows just 1.6 to 3.9 feet of sea level rise through 2100.

The new study paints a far more alarming picture compared to what the IPCC found, which was a median projection of two feet and five inches of sea level rise by 2100 under a high emissions scenario. Most sea level rise predictions since that report was published have indicated that figure was too low, however.

The study shows that global average sea level is projected to increase by one foot by the year 2050, and several more feet by the year 2100, depending on the significance of any cuts to greenhouse gas emissions. If the temperature targets in the Paris Climate Agreement are met — which is a big if at the moment — then we’re unlikely to trigger a rapid Antarctic meltdown, the study found.

Prior sea level rise projections have not included the recently discovered mechanism of marine ice-cliff instability in Antarctica. Instead, those projections relied on other assumptions of how significantly the Greenland and Antarctic Ice Sheets might melt during the course of the 21st Century. Nor have they included all of the ways that floating ice shelves might disintegrate rapidly, either, weakening inland ice………. http://mashable.com/2017/12/13/sea-level-rise-could-be-double-previous-estimates-climate-change-study/#rZy6GL2FCSqM

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December 16, 2017 - Posted by | 2 WORLD, climate change

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