Was April in the #Arctic regular or record breaking?

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Broken up sea ice and some multi-year floes at Alert, on the northern tip of Ellesmere Island, Canada – April 2017. A researcher and a Twin Otter aircraft are obscured in the background.
Credit: J. Stroeve/NSIDC

NSIDC have published their April update, and that of course prompts a question. Has it been a normal average dull April with nothing of note, or do we have a new low?

Arctic sea ice extent for April 2017 tied with April 2016 for the lowest in the satellite record for the month. Warm weather conditions and lower-than-average sea ice extent prevailed over the Pacific side of the Arctic, while relatively cool conditions were the rule in northern Europe and eastern North America. In the Southern Hemisphere, Antarctic sea ice extent remained lower than average.

… and to be a tad more specific about the #Arctic sea ice numbers …

Arctic sea ice extent for April 2017 averaged 13.83 million square kilometers (5.34 million square miles), and tied with April 2016 for the lowest April extent in the 38-year satellite record. The April 2017 extent is 1.02 million square kilometers (394,000 square miles) below the April 1981 to 2010 long-term average.

This past April was a month that was very similar to the seasonal decline observed in the previous two years. As the month proceeded, we were at record lows for the entire period of satellite observations or at least within 100,000 square kilometers of that.

Young Sea Ice

Part of the overall saga here is not simply a decline in the extent, but also a decline in the quantity of old sea ice. Below is a chart that illustrates how the quantity of ice that survives the summer melt and makes it into the next year has been rapidly shrinking …

Credit: National Snow and Ice Data Center, courtesy M. Tschudi, C. Fowler, J. Maslanik, R. Stewart/University of Colorado Boulder; W. Meier/NASA Cryospheric Sciences

What the above shows you is as follows. The top left illustrates where old sea ice was at the end of March 2016. Top right is one year later at the end of March 2017. The graph under both of these illustrates how the older sea ice has been declining over time.

What is shocking here is that in the mid 1980s as much as one third of Arctic sea ice was five years or older, and now that is only about 5%. The location of the old sea ice is also changing. In contrast to the previous year it is now all squashed up against Greenland.

The transition of the arctic to a new state continues and we observe that the overall warming trend is ongoing.

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As usual, the subject matter experts have a few nice graphs that illustrate the overall trend and big picture here.

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