Risk of ice-free Arctic still high, even with climate action
Monday, March 6, 2017, 9:05 PM - Even as the world mobilizes to limit and eventually stop global greenhouse gas emissions, a new study is showing that there is still a high risk of seeing ice-free summers in the Arctic, despite these efforts.
Arctic sea ice has been on an ever-increasing decline over the past few decades, and although there were high hopes that the recent Paris Climate Agreement would prevent the Arctic from going completely ice-free during the summer months, a new study is showing that may not be the case.
The current goal of the nations who have signed on to the Paris Agreement is to keep global temperature rise to a maximum of 2oC above the pre-industrial average. This is in an effort to avoid the worst affects of global warming and climate change.
This goal has already been shown to be insufficient to prevent irrevocable damage to island nations, who stand to lose the most due to global sea level rise. During the talks in Paris, these island nations came together to propose an even more ambitious goal, of keeping global temperature rise to less than 1.5oC above what it was in pre-industrial times.
As they showed in their proposal, even that 0.5oC difference between the two goals was enough to prevent them from losing their homes to expected sea level rise.
Now, based on the research of James Screen and Daniel Williamson, of the University of Exeter, in the UK, it seems that same difference is needed for the Arctic to maintain a significant area of sea ice, all year long.
"We estimate there is less than a 1-in-100,000 (exceptionally unlikely, in IPCC parlance) chance of an ice-free Arctic if global warming stays below 1.5oC," they wrote in a letter, published on March 6, in the journal Nature Climate Change, "and around a 1-in-3 chance (39%; about as likely as not, in IPCC parlance) if global warming is limited to 2.0oC."
Thus, by sticking with the 2oC goal, the future state of summer Arctic sea ice is really still left up in the air. Restricting emissions even further, to limit warming to 1.5oC, could make all the difference.
The lowest summer sea ice extent seen so far in the Arctic, according to official records going back to 1979, was in September of 2012, when extent reached 3.387 million square kilometres - a little over 3 million square kilometres lower than the 30 year average from 1981-2010.
According to the Intergovernmental Panel on Climate Change (IPCC), the Arctic Ocean would be considered ice-free if it reached a sea ice extent of 1 million square kilometres or less, for a period of at least five years. That remaining area would be restricted to patches of water between the islands in the Canadian Arctic, and in bays and inlets along the northern coast of Greenland.
The current state of sea ice?
Credit: NSIDC/S. Sutherland
Currently, sea ice extent in the Arctic is nearing its winter maximum, which could end up being the lowest winter maximum on record.
Credit: NSIDC/S. Sutherland
In the Antarctic, sea ice extent is either at or near its summer minimum, and now ranks as the lowest summer minimum on record, after several years of record high summer extents.