Tag Archives: Thickness

Facts About the Arctic in November 2025

The latest Alfred Wegener Institute sea ice concentration map shows the East Siberian and Laptev Seas almost completely refrozen. However, refreeze of the Kara Sea has barely begun:

Across the Arctic as a whole the refreeze has slowed significantly, and JAXA/ViSHOP extent is now 2nd lowest in the satellite era:

However, average NSIDC extent for the month of October was higher than last year and above the linear trend:

The ERA5 MSLP map for October shows high pressure over Siberia, associated with lower than normal air temperatures at 925 hPa across the region. However, temperatures across almost the entire Arctic Ocean were above normal:

High Arctic freezing degree days based on DMI >80N data were lowest for the date at the beginning of November:

Here is the Alfred Wegener Institute’s CryoSat-2/Sentinel 3/SMOS Arctic sea ice thickness map at the end of October:

Here too is the associated sea ice volume graph:

Bear in mind the caveats about the current lack of reliable SMOS data on the Atlantic side of the Arctic, and that Sentinel 3 data is only incorporated from Autumn 2023.

[Update – November 20th]

Refreeze of the Beaufort Sea is complete, and refreeze of the Kara Sea has started in earnest:

However, the Barents Sea is still sea ice free and refreeze of Hudson Bay has barely begun:

JAXA extent is still second lowest for the date:

The PIOMAS gridded thickness data for October has yet to be corrected, but here is the mid month thickness map from AWI:

Here too is the associated volume graph:

[Update – November 27th]

JAXA/ViSHOP extent is now lowest for the date in their record going back to 1978:

[Update – December 5th]

The PIOMAS team have finally published gridded thickness data for October and November, so here are the October 31st and November 15th thickness maps:

The conversation continues over on the December open thread, including the latest PIOMAS data.

Facts About the Arctic in September 2025

At the beginning of last month JAXA/ViSHOP extent was third lowest for the date in the satellite era. With the date of the 2025 minimum extent rapidly approaching that is no longer the case:

Whilst JAXA extent is now 10th lowest, PIOMAS volume remains second lowest for the date:

Here’s the associated thickness map. Note the change of scale from last month

Compare and contrast that map with the AWI’s sea ice concentration map, particularly in the Beaufort Sea area:

Continue reading Facts About the Arctic in September 2025

Facts About the Arctic in August 2025

At the beginning of August JAXA/ViSHOP extent is in a “statistical tie” for 3rd lowest for the date in the satellite era:

Extent has been declining rapidly for the past few days, and further losses look likely in the Beaufort Sea on either side of an arm of high concentration ice visible in the Alfred Wegener Institute’s map of sea ice concenration:

The ice on the Atlantic side of the Arctic is starting to look highly fragmented, all the way to the North Pole.

Continue reading Facts About the Arctic in August 2025

Facts About the Arctic in July 2025

At the beginning of July JAXA/ViSHOP Arctic sea ice extent is still “lowest for the date” in their record going back to 1979:

The PIOMAS sea ice thickness map for June 30th reveals that the previously thick ice in the Chukchi Sea has been noticeably thinning:

The associated volume graph shows that the 2025 curve has entered the pack of other recent years. and is now 4th lowest for the date:

Continue reading Facts About the Arctic in July 2025

Facts About the Arctic in June 2025

I’ve been away on a “road trip” during the first part of June, so this month’s initial update is a trifle tardy.

After a 100k “break” yesterday JAXA/ViSHOP extent is currently in a tie with 2024 for 4th lowest for the date, and still slightly below 2012.

The PIOMAS sea ice thickness map for May 31st continues to show plenty of thick ice in the Beaufort and Chukchi Seas:

However, the associated volume graph shows the 2025 curve only slightly above the previous low for the date in 2017:

I have recently received a disturbing email from the NSIDC, which reads as follows:

Continue reading Facts About the Arctic in June 2025

The Northwest Passage in 2025

I’m opening the 2025 Northwest Passage thread earlier than usual, because of some news you can read if you scroll down. However, let’s first of all get our bearings with the help of this map of the area:

and another map detailing the routes through Canadian Arctic Archipelago that have previously been successfully traversed:

The news I was referring to is that at lunchtime today Ella Hibbert is setting off in her yacht Yeva from Haslar Marina near Portsmouth in southern England for a rather unusual voyage through the Northwest Passage this summer. Here is Ella’s current route plan:



You will note some unusual features. Apparently Ella is intent on taking Route 1 into the Beaufort Sea via McClure Strait. After that she is not heading for the Bering Strait, but is instead taking the route less travelled back to Haslar via the Northern Sea Route. Perhaps even more surprising in this day and age is that Ella has received permission to sail through Russian waters without an ice pilot. She is aiming to complete an entire circumnavigation of the Arctic in a single summer single handed! As Ella puts it, this is “A voyage that should not be possible”:

Ella is hoping to overcome terrifying challenges including icebergs, freezing water and polar bears.

Her journey – which has only recently become possible due to melting polar ice caps – aims to showcase the devastating environmental impact of sea ice decline, both in the Arctic and across the world.

Ella’s voyage also aims to support two charities working tirelessly to protect the Arctic: Polar Bears International and the Ocean Conservancy.

At the end of her voyage, Ella will auction her ship Yeva with proceeds to go to these two charities.

Continue reading The Northwest Passage in 2025

Facts About the Arctic in April 2025

JAXA/ViSHOP extent finished the month of March “lowest for the date” once again:

However, since then the graph has been “flatlining” and extent is now above 2019 and rapidly approaching the rest of the recent pack.

At the end of March PIOMAS Arctic sea ice volume had increased to 21.21 thousand km³, still 2nd lowest for the date in the PIOMAS record:

Here is the corresponding PIOMAS sea ice thickness map for March 31st 2025:

For comparison purposes, here is the “near real time” CryoSat-2/SMOS merged thickness data from the Alfred Wegener Institute: 

Continue reading Facts About the Arctic in April 2025

Facts About the Arctic in March 2025

After spending several weeks in the unfortunate position of lowest for the date, JAXA/ViSHOP Arctic sea ice extent has just risen above 2015. By a mere 10,000 km²:

Despite the fact that JAXA extent is still rising, AWI extent has potentially already achieved its maximum value for 2025:

Somewhat belatedly, here is the PIOMAS sea ice thickness map for February 28th 2025:

At the end of February Arctic sea ice volume had increased to 19.32 thousand km³, still 2nd lowest for the date in the PIOMAS record:

For comparison purposes, here is the “near real time” CryoSat-2/SMOS merged thickness data from the Alfred Wegener Institute: 

AWI have also released a new version of their thickness product, incorporating additional data from the two Sentinel 3 satellites. The thickness data for February 28th, looks slightly different:

Continue reading Facts About the Arctic in March 2025

Facts About the Arctic in January 2025

The New Year began with JAXA/ViSHOP extent lowest for the date in the satellite era, just below 2018 . Since then extent has reduced, and there is now a large gap:

The primary reason for this is the remaining open water in Hudson Bay:

In previous years Hudson Bay has been covered by sea ice by this time of year, but in 2025 a large area remains unfrozen in early January!

Due to the way PIOMAS handles the leap years the last gridded thickness data of 2024 is dated December 30th:

By December 30th Arctic sea ice volume had increased to 13.61 thousand km³, 2nd lowest for the date in the PIOMAS record:

Continue reading Facts About the Arctic in January 2025

Facts About the Arctic in December 2024

Christmas is coming, and even as we speak Snow White is heading for the geographical North Pole to assist Santa’s little helpers in their annual gift delivery mission:

Santa at the North Pole in August 2016

We’ll start the festive season with a graph of JAXA/ViSHOP extent, which is in a “statistical tie” with 2020 for 2nd lowest for the date in the satellite era:

Here’s the PIOMAS gridded thickness data for the end of November 2024:

On November 30th Arctic sea ice volume had increased to 9.99 thousand km³, 3rd lowest for the date in the PIOMAS record:

For comparison purposes, here is the “near real time” CryoSat-2/SMOS merged thickness data from the Alfred Wegener Institute: 

Continue reading Facts About the Arctic in December 2024