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PIOMAS December 2018

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

BPIOMASIceVolumeAnomalyCurrentV2.1_CY

November has been an excellent month for Arctic sea ice. With 4226 km3, it recorded the highest volume increase for November in the 2007-2018 period, well above the average of 3491 km3. The reasons for this are obvious: rapid growth in ice extent and relatively low temperatures (more on that below). This means that 2018 has dropped from 4th lowest to 6th lowest, and the gap with leader 2016 has grown by a whopping 1322 km3!

Here’s how the differences with previous years have evolved from last month:

Change monthly difference November 2018

Because all the trend lines go up fast around this time of year, I’m posting another Wipneus graph that visualises PIOMAS volume anomaly, showing 2018’s massive increase more clearly:

Piomas-trnd3

On the PIOMAS volume anomaly graph we see a massive surge towards 2 standard deviation territory:

Change monthly difference November 2018

As for average thickness (crudely calculated by dividing PIOMAS volume numbers with JAXA extent), it hasn’t increased as spectacularly, which means that that the spectacular increases in both volume and extent cancelled each other out. This may seem counter-intuitive, but thickness only changes radically if one of the two parameters does so as well, while the other doesn’t change as fast. And so the 2018 trend line goes up, more or less in tandem with the other trend lines: PIJAMAS 20181130

The Polar Science Centre version basically shows the same, as it often does:

Change monthly difference November 2018

And now for temperatures and ice extent.

As Zack Labe‘s excellent monthly air temperature ranks (north of 70°) show, this past November was 12th warmest on record:

925T_70N_rank

I have the Arctic at 8th warmest on record for November, but instead of 70N, I use data from 65N to 90N. Apparently there was even more cold in those five degrees latitude to cause such a stark discrepancy between Zack’s and my graphs. The lowest graph shows temperatures for the four quadrants I’ve divided the Arctic into (map is top right), and even though the Atlantic quadrant was second lowest on record, temperatures in Siberia absolutely plummeted from the record-breaking peak in October, while Pacific and Canadian also dropped compared to previous years:
925T_70N_rank

It only makes sense that this winter’s trend line on Tealight‘s Freezing Degree Days graph (this is for north of 80°, based on the DMI 80N graph) could no longer manage to keep up with crazy 2016:

DMI_FDD_Season_AnomOf course, the Arctic wouldn’t be the Arctic, if it didn’t let one radical swing get followed by another radical swing. While November also saw the largest increase in sea ice extent in the 2005-2018 period, with 2018 at one point almost taking the second highest position, the trend line on the JAXA graph has effectively flatlined into December and may very well be second lowest tomorrow: JAXA SIE 20181205That’s a big change, taking place in less than two weeks. No telling what the Arctic will do next, but I don’t expect very large shifts in the PIOMAS ranking at the end of December, as most years don’t deviate more than 200 km3 from the 2007-2017 average.

Three more weeks and it’s time to update spreadsheets for a new year of Arctic sea ice extravaganza. Have a good end of the year, everyone.