What Do We Know About Arctic Sea ice Trends?

  • Date: 17/08/17
  • Dr. Ronan Connolly & Dr. Michael Connolly, Climate Etc.

Satellite observations indicate that the average Arctic sea ice extent has generally decreased since the start of the satellite records in October 1978. Is this period long enough to assess whether the current sea level trend is unusual, and to what extent the decline is caused by humans?

This change in Arctic climate is often promoted as evidence that humans are causing drastic climate change. For instance, an April 29th 2017 article in the Economist (“Skating on thin ice”, pg 16) implied that the Arctic is melting unusually, dramatically and worryingly:

“The thaw is happening far faster than once expected. Over the past three decades the [Arctic sea ice extent] has fallen by more than half and its volume has plummeted by three-quarters… SWIPA estimates that the Arctic will be free of sea ice in the summer by 2040. Scientists previously suggested this would not occur until 2070.”

However, is the 1978-present satellite record really long enough to allow us to:

  1. a) Assess how unusual (or not) the recent trends are?
  2. b) Determine how much of the recent climate change is human-caused vs. natural?

Recently, we published a study in Hydrological Sciences Journal (HSJ) in which we extended the Arctic sea ice estimates back to 1901 using various pre-satellite era data sources (Abstract here).

HSJ have chosen this article as one of their “Featured Articles” which means that it is free to download for a limited time: here. But, if you’re reading this post after that offer has expired and you don’t have paywall access, you can download a pre-print here.

In our study, we found that the recent Arctic sea ice retreat during the satellite era actually followed a period of sea ice growth after the mid-1940s, which in turn followed a period of sea ice retreat after the 1910s. This suggests that the Arctic sea ice is a lot more dynamic than you might think from just considering the satellite records (as the Economist did above). So, in this post, we will review in more detail what we currently know about Arctic sea ice trends.

Full post



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