Death Spiral Watch: Experts Warn 'Near Ice-Free Arctic in Summer' in a Decade if Trends Continue
High levels of carbon dioxide in the atmosphere may have less of an impact on the rate of global warming than feared, a study said.
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The sharp drop in Arctic sea ice area has been matched by a harder-to-see — but equally sharp — drop in sea ice thickness. The combined result has been a collapse in total sea ice volume.
Many experts now say that if recent volume trends continue we will see virtually ice-free conditions sometime in the next ten years. And that may well usher in a permanent change toward extreme, prolonged weather events “Such As Drought, Flooding, Cold Spells And Heat Waves.”
It will also accelerate global warming in the region, which in turn will likely accelerate both the disintegration of the Greenland ice sheet and the release of the vast amounts of carbon currently locked in the permafrost.
The European Space Agency’s CryoSat-2 probe confirms what the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center has been saying for years: Arctic sea ice volume has been collapsing faster than sea ice area (or extent) because the ice has been getting thinner and thinner.
In fact, the latest satellite CryoSat-2 data shows the rate of loss of Arctic sea ice is “50% higher than most scenarios outlined by polar scientists and suggests that global warming, triggered by rising greenhouse gas emissions, is beginning to have a major impact on the region,” as the UK Guardian reported last month:
If the current annual loss of around 900 cubic kilometres continues, summer ice coverage could disappear in about a decade in the Arctic.
I have focused on sea ice volume for the past 6 years, since I was fortunate enough to hear Dr. Wieslaw Maslowski of the Oceanography Department at the Naval Postgraduate School in a 2006 American Meteorological Society seminar. He reported that models suggested Arctic ice volume had dropped sharply since the mid 1990s. He then made an alarming forecast:
That was in 2006, so he was talking about the possibility of being ice free in 2016.
Looking at volume and thickness helped me avoid the mistake that so many others made in thinking that the sea ice “recovered” after the 2007 minimum in sea ice extent. The scientific literature and actual observations continued to vindicate Maslowski’s projection.
Since Maslowski’s warning appears to now have been vindicated by the CryoSat-2 data, I asked him for a comment. He said he didn’t want to comment on that data specifically until he’s seen the published results — since there are many inherent uncertainties involved. But he then added:
Regardless of all these uncertainties and for the record, if any of these estimates of arctic sea ice volume decline is close to reality, a near ice-free Arctic in summer can happen not in 2100, 2050 or 2037 but much sooner. One of the main reasons I believe it will happen sooner (i.e. the trend of sea ice volume decline will continue) is that with the shrinking sea ice cover in summer the Arctic Ocean increases its net annual heat content through absorption and redistribution, especially in the upper water column, below the surface mixed layer.
This constitutes a positive feedback to sea ice melt in addition to ice-albedo and other feedbacks, mainly because it can affect the sea ice cover year around, including in winter through upward heat entrainment and reduction of ice growth. The warmer Arctic Ocean can also affect air temperatures and circulation, not only during freeze-up but also in winter and spring. Observational evidence (Jackson et al., 2010 and 2011) suggests increasing sub-surface temperatures and over increasing area in the Canada Basin through 2009, which independently of models supports the argument about the increasing upper ocean heat content.