Daily Archives: May 15, 2018

Polar bear habitat update mid-May: little change since 1989 despite CO2 increase

Sea ice habitat for polar bears has not become progressively worse each year during their season of critical feeding and mating, as some scaremongers often imply. It’s true that absolute extent of Arctic ice is lower this spring than it was in 1979. However, according to NSIDC Masie figures, polar bear habitat at mid-May registers about 12 million km2, just as it did in 2006 (although it is distributed a little differently); other data show spring extent has changed little since a major decline occurred in 1989, despite ever-rising CO2 levels.

Polar bear feeding_Shutterstock_sm

In other words, there has been virtually no change in sea ice cover over the last 12 years, despite the fact that atmospheric CO2 has now surpassed 410 parts per million, a considerable and steady increase over levels in 2006 which were about 380 ppm (see below, from the Scripps Oceanographic Laboratory, included in the Washington Post story 3 May 2018):

Scripps CO2 curve at 29 April 2018

Not only that, but if rising CO2 levels were responsible for the decline of sea ice and implied effects on polar bears since 1979 (when CO2 levels were around 340 ppm), why has spring ice extent been so variable since 1989 (when the first big decline occurred) but so little changed overall since then? See the NSIDC graph below for April:

Sea ice 2018 April average_NSIDC graph

This year on day 134 (14 May), global ice cover registered 12.3 mkm2:

masie_all_zoom_4km 2018 May 14

In 2016 on the same day, the overall extent was much the same but there was more ice in the Chukchi and Bering Seas and less in the eastern Beaufort:

masie_all_zoom_4km 2016 May 14

More close-up charts of different regions below for 2018 vs. 2016, showing more detail.

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