22 November 2016

We are in unprecedented territory with global sea ice

Posted by Callan

The amount of our planet’s ocean area covered by ice is at an unprecedented low for this time of year. It is the Arctic winter, the long night when no sun shines on that northerly ocean, and yet temperatures there are averaging 10°C above normal. My attention was called to this issue last week thanks to the Twitter feed of Zack Labe, a PhD student in Earth Systems Science at the University of California – Irvine. He makes great graphics showing the latest data on polar climate. Here’s his latest temperature map for the Arctic, for instance:

labeClick for source

Water there is accordingly failing to freeze. Meanwhile, down south, the Antarctic summer is getting cranked up, and that sea ice is melting. When these two polar situations are summed, we see that there is less sea ice on Earth for this time of year than we have ever seen since we started keeping track of it. This graph, not by Zack by by Wipneus (click for source), shows the current situation in the context of the entire record:

nsidc_global_extent_byyear_bClick for source

Zack Labe breaks out each pole independently, if you’d like to see that:

This deviation from the trend of previous years is utterly anomalous. Will it turn out to be a unique diversion that we’ll end up chalking up to the mere vicissitudes of “weather?” Or is this what a tipping point looks like when it is finally reached?

Time will tell.