NSIDC: Are scientists conservative about sea ice?
Guest post by Dr. Walt Meier on NSIDC Icelights:
Are scientists conservative about sea ice?
Scientists by their nature tend to be conservative when viewing new evidence. While the recent years have been surprising, most scientists are not willing to accept that ice-free conditions are imminent. But that is not because they’re being too conservative. The Arctic sea ice system is complex and there are many aspects that are not yet well understood.
A variety of feedbacks promote ice growth or ice loss. For example, sea ice has a high albedo, meaning it reflects the sun’s energy back into space. Darker ocean water has a low albedo, meaning it absorbs more of the sun’s energy, and thus more heat. As sea ice extent decreases, the change in albedo spurs a well-known feedback that enhances summer melt because the ocean absorbs more of the sun’s energy than the ice.
Likewise, there are also negative feedbacks that will slow the loss of ice. One of these results from the fact that ice grows more rapidly when there is no ice or thin ice than when thick ice is present under the same air temperatures. Thus in fall when the sun goes down and the atmosphere gets cold, open water areas grow ice quickly allowing such regions to “catch up” to thicker ice regions. These feedbacks and many other factors, such as ocean and air temperatures, wind, and weather patterns, prevent an easy assessment of a complex system.
One thing that all scientists who study sea ice agree upon is that under increasing temperatures, the overall long-term declining trend will continue and some summer in the future, we will look down on the North Pole and see a blue Arctic Ocean. It’s not a matter of if, but when
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