Tracking polar bears in the Beaufort Sea in July & sea ice comparison with 2007/2012

Only four Alaskan polar bear females had USGS satellite collars left transmitting locations in the Beaufort Sea and all four of these bears were on the ice during July, 2016. The same was true in June and May.

Beaufort tracking USGS bear-movements-July 2016 sm

Original caption: “Movements of 4 satellite-tagged polar bears for the month of July, 2016. Polar bears were tagged in 2015 and 2016 on the spring-time sea ice of the southern Beaufort Sea. All 4 of these bears have satellite collar transmitters. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage from 31 July, 2016.” Original here.

 

There looks like a lot of open water for this time of year but in terms of absolute extent there is somewhat less ice than there was in 2007 and only slightly less than 2012, according to NSIDC Masie charts. And of course, what we know is that polar bears of the Chukchi Sea and the Southern Beaufort not only survived the low ice summers of 2007 and 2012, they thrived: CS bears were in great condition and reproducing well, and BS bears were recovering from the devastating thick ice conditions of the 2004-2006. Have a look at the maps below.

First, get yourself oriented (note that Wrangel Island is just above the ‘Chukchi’ label):

Chukchi Beaufort at Aug 27 2007

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in September 2008 and 2010, while 2009 was more like 2013.

Here is the NSIDC Masie ice map for 5 Aug. 2016 – less ice than 2007 in the Beaufort this year but more of it is near shore:

masie_all_zoom_4km 2016 Aug 5

And the same date back in 2007 – somewhat more ice in the Beaufort in 2007 but much less in the Chukchi than 2016, with no ice at all around Wrangel Island or near the Alaskan coast (and yet, both CS and BS polar bears did just fine, see this post on CS bears):

masie_all_r00_v01_2007217_4km_cropped

And what about 5 Aug. 2012 (remember, the lowest summer ice extent since 1979 happened in 2012)? Slightly more ice in the Beaufort in 2012 than this year and more in the Chukchi Sea in early August:

masie_all_r00_v01_2012218_4km_cropped

 

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