Category Archives: Extent

The 2021 Arctic Sea Ice Minimum Extent

August 29, 2021ExtentAlek Petty, AWI, Beaufort Sea, Chukchi Sea, Extent, Fram Strait, Greenland Sea, JAXA, Kara Sea, Laptev Sea, Linette Boisvert, NASA, NSIDC, OSI-SAF, SIPNJim Hunt

The results of the ARCUS Sea Ice Prediction Network August call have been released, and here is the outlook for the 2021 ~~minimum~~ September mean Arctic sea ice extent:

The median prediction for the mean sea ice extent during the month of September 2021 is 4.39 million km². According to ARCUS:

As of 22 August 2021, the Arctic sea-ice extent was 5.58 (compared with 25 August 2020 value of 4.43) million square kilometers. Arctic sea-ice extent in 2021 remains well below the climatological median and has closely followed the 2012 values for much of the summer but has diverged to higher sea-ice extent starting in early August. The forecasts continue to support September 2021 mean sea-ice extent being well above the September 2020 value. July sea-ice retreat has been greatest in the Eurasian seas, particularly in the East Siberian Sea, making the 2021 ice edge well north of the long-term median edge in Eurasia. Sea ice retreated since the end of July along the northern coast of Alaska, although the ice edge is near its climatological position, which makes the Beaufort and Chukchi sea ice extent the largest at this time of year since 2006. A tongue of sea ice that has been present all summer continues to extend close to land in the Kara Sea, making the northeast passage likely to remain blocked for the first time in several years. Half the models which provide spatial data to the SIO predict that the tongue is likely to survive.

Now let’s take a look at a range of assorted extent measurements. Here’s the NSIDC’s 5 day average extent:

The 2021 Maximum Arctic Sea Ice Extent

February 18, 2021ExtentAMSR2, Bering Sea, CMEMS, ESS, Extent, JAXA, NSIDC, Sea Of Okhotsk, Thomas Lavergne, Worldview, Zack LabeJim Hunt

Here’s the latest graph of Arctic sea ice extent from JAXA/ViSHOP, with 2021 and 2015 highlighted:

Extent fell by over 100,000 square kilometres between February 16th and 17th! Can that steep fall continue, as it did for one more day in 2015?

Here too is Zack Labe’s 2021 overview of JAXA maximum extent over the previous couple of decades:

2015’s maximum was very early, on February 15th. Hence the current extremely tentative 2021 maximum is already both higher and later than that. The decadal average extent graphs show the date of the maximum getting later and later, and the 2010’s peaks in the middle of March.

It therefore seems likely that there is more freezing still to come this year. However lets take a look at the high resolution AMSR2 sea ice area graph for the Sea Of Okhotsk:

The recent fall in Arctic wide extent has evidently been driven by the recent rapid decline in this peripheral sea, where SMOS reveals more thin ice ripe for further melting:

In conclusion, the high res AMSR2 extent metric shows the tentative 2021 peak below that of 2015!

Facts About the Arctic in April 2020

March 29, 2020ExtentAMSR2, CryoSat-2, Extent, JAXA, Martin Dameris, NASA, Ozone, PIOMAS, SMOS, Thickness, VolumeJim Hunt

This comes to you a couple of days early, but the clocks have just changed to British Summer Time in the once United Kingdom and there is news to impart.

JAXA Arctic sea ice extent has fallen to the lowest level for the date in their satellite era records going back to 1979. This graph shows every year since 2000:

The 2020 Maximum Arctic Sea Ice Extent

February 22, 2020ExtentAMSR2, CryoSat-2, Extent, JAXA, NSIDC, SMOS, Tony Heller, Volume, Wipneus, Zack LabeJim Hunt

As Zack Labe has recently pointed out, in 2015 the Arctic sea ice maximum extent based on the JAXA numbers had already occurred on February 15th:

Perhaps it’s time we started paying attention this year! However the National Snow and Ice Data Center reported a significantly later date in 2015:

The 2019 Arctic Sea Ice Metric Minima

September 12, 2019ExtentArea, CAA, Extent, Greenland, Hamburg Uni, JAXA, NSIDC, PIOMAS, Volume, Walt Meier, WipneusJim Hunt

September is here once again, so the assorted minima of a variety of Arctic sea ice metrics will be reached soon, if they haven’t happened already!

In the latter category let’s first take a look at the NSIDC’s 5 day averaged SSMIS based Arctic sea ice extent:

The 2019 Maximum Arctic Sea Ice Extent

March 1, 2019ExtentAMSR2, Beaufort Sea, Bering Sea, Chukchi Sea, CryoSat-2, DMI, Extent, FMI, Hamburg Uni, JAXA, NSIDC, OSI-SAF, Sea Of Okhotsk, SMOS, St. Lawrence, Thickness, WipneusJim Hunt

March 2019 has arrived, which in recent years has proved to be by far the likeliest month to contain the maximum extent of Arctic sea ice for the year. To begin with, here’s our favourite high resolution extent graph calculated by “Wipneus” from University of Hamburg/JAXA AMSR2 data:

The 2018 Arctic Sea Ice Metric Minima

September 2, 2018ExtentAMSR2, Andrew Slater, Area, Concentration, Extent, Hamburg Uni, NSIDC, PIOMAS, SMOS, Volume, WipneusJim Hunt

September is upon us once again, the month in which the assorted Arctic sea ice area and extent metrics (almost) always reach their respective annual minima. Now we are free to start speculating about what the assorted minima will be, and on what date.

The 2018 Maximum Arctic Sea Ice Extent

March 25, 2018ExtentAMSR2, Barents Sea, Bering Sea, Bremen Uni, CryoSat-2, Extent, Hamburg Uni, JAXA, NIPR, NSIDC, Sea Of Okhotsk, SMOS, WipneusJim Hunt

According to the latest edition of the National Snow and Ice Data Center’s “Arctic Sea Ice News”

On March 17, 2018, Arctic sea ice likely reached its maximum extent for the year, at 14.48 million square kilometers (5.59 million square miles), the second lowest in the 39-year satellite record, falling just behind 2017. This year’s maximum extent is 1.16 million square kilometers (448,000 square miles) below the 1981 to 2010 average maximum of 15.64 million square kilometers (6.04 million square miles).

The 2017 Arctic Sea Ice Metric Minima

September 3, 2017ExtentAMSR2, Area, Donald Trump, Extent, Hamburg Uni, Michael Scott, NSIDC, PIOMAS, Tony Heller, Volume, WavesJim Hunt

September has arrived once again, the month in which the assorted Arctic area and extent metrics (almost) always reach their respective annual minima. Now we can start to speculate about what the assorted minima will be, and on what date.

The 2017 Arctic Sea Ice Maximum Extent

February 22, 2017ExtentAMSR2, Area, CT, Extent, JAXA, NSIDC, SII, UH, WipneusJim Hunt

It’s far too early to be sure about this yet, but it’s not beyond the bounds of possibility that the 2017 maximum is already in place. Here’s our favourite high resolution extent graph calculated by “Wipneus” from University of Hamburg/JAXA AMSR2 data:

The Great White Con

Putting the Arctic sea ice record straight