Arctic sea ice extent in early April is singularly unexceptional. Here’s the AWI AMSR2 version:
Things start to become more interesting when looking at the third dimension. Here’s the PIOMAS gridded thickness map for March 31st:
and the CryoSat-2/SMOS map for the same date:
Note the differing distribution of thick ice north of Greenland and the Canadian Arctic Archipelago between the two maps. Note also the area of thinner ice along the coast of the Beaufort Sea visible on the CS2/SMOS map.
By way of explanation for that phenomenon see the March sea level pressure map from the latest edition of the NSIDC’s Arctic Sea Ice News:
The persistent low pressure on the Siberian side of the Arctic together with high pressure over Greenland has led to significant ice drift from Alaska towards Svalbard. If you have the bandwidth for a multi megabyte download click the following image of AWI AMSR2 sea ice concentration to see an animation revealing the resulting disappearance of the area of open water north of Svalbard, and also periods of open water along the Beaufort Sea coast:
At this time of year that open water has refrozen, but another effect of the persistent ice drift is that the familiar arm of old ice in the Beaufort Sea has moved well to the north:
All of which suggests that this year a relatively early melt in the Beaufort Sea is likely.
The other side of the ice drift coin is that there is now plenty of old ice in the East Greenland Sea, and that regional ice extent on the Atlantic side of the Arctic is anomalously high this year:
How long do you suppose it will take for all the extra ice currently heading south past the east coast of Greenland to melt?
[Edit – April 19th]
The mid April PIOMAS gridded thickness data has been released. Here’s the modelled thickness map:
The calculated volume is still increasing, and is now 11th lowest for the data in the satellite era:
However the final near real time CryoSat-2/SMOS data of the 2022/23 season tells a different story. Here’s the thickness map:
The volume graph shows that Arctic sea ice volume is now declining:
The maximum seems certain to increase when the reanalysed data is released in a few weeks time, but the NRT peak is 17,820 km3 on April 7th.
CryoSat-2 and SMOS thickness data becomes unreliable after the middle of April as melt ponds begin to form on sea ice in the Arctic, so here too is the current SMOS “thin ice thickness” map:
Note in particular the areas of thin ice in the Laptev and eastern Beaufort Seas.
We’ll come on to the Arctic in a moment, but at more temperate latitudes I am proud to announce that my Cornish alter ego has been officially outed as an “environmental campaigner” by the BBC. Moving pictures of yours truly, discussing drought rather than sea ice, are available via BBC iPlayer until around 18:30 this evening, possibly to UK residents only.
[Stop Press! A shorter version of Kirk England’s report on two potential desalination plants in Cornwall (also including my 15 seconds of fame!) is available here until around 22:30 this evening ]
Alternatively we have recorded our own moving pictures of this momentous event:
Zack’s graph displays the JAXA/ViSHOP version of Arctic extent, so here too is JAXA’s own graph of the current sea ice extent:
It doesn’t look as though the 2023 maximum has been achieved yet, but extent on March 1st was 14.01 million km². That is evidently not going to be the lowest in the satellite era!
[Edit – March 8th]
As Tom has already mentioned below, JAXA extent has declined significantly since the (so far!) peak extent of 14.12 million km² on both the 2nd and 3rd of March:
It’s too soon to be certain of course, but we certainly now have a good candidate for the 2023 maximum JAXA extent.
NSIDC 5 day averaged extent is still increasing, but let’s see what this afternoon’s update (UTC) reveals…
Which is a decrease of 0.001 million km² from March 6th, leaving a current NSIDC maximum extent of 14.62 million km²!
Finally, for the moment at least, AWI’s “high resolution” AMSR2 extent looks a lot less convincing than JAXA’s:
[Edit – March 11th]
NSIDC Arctic sea ice extent took a tumble yesterday, so with only mild trepidation I’m calling the 2023 maximum extent. In the case of the NSIDC’s 5 day average metric that’s still a rounded up 14.62 million km² on March 6th:
The JAXA/ViSHOP maximum extent remains at 14.12 million km² on March 2nd:
The “high resolution” AMSR2 based metric from AWI peaked at 14.24 million km² on March 5th:
Arctic sea ice has likely reached its maximum extent for the year, at 14.62 million square kilometers (5.64 million square miles) on March 6. The 2023 maximum is the fifth lowest in the 45-year satellite record. NSIDC scientists will present a detailed analysis of the 2022 to 2023 winter sea ice conditions in the regular monthly post in early April:
The date of the maximum this year, March 6, was six days earlier than the 1981 to 2010 average date of March 12…
The ice growth season ended with below average sea ice extent in the Bering Sea, Sea of Okhotsk, Barents Sea, and Labrador Sea. Above average extent was in the Greenland Sea. Extent was well below average in the Gulf of St. Lawrence for a second year in row.
I should of course add “in the satellite era”, but the title is pretty unwieldy as it is!
I was up early (UTC) to check the latest JAXA data, and sure enough that confirmed a new record minimum Antarctic sea ice extent of 2.11 million km² was reached yesterday:
Having added a note to that effect the Arctic open thread, Lars Kaleschke from the Alfred Wegener Institute pointed out over on Mastodon that the AWI had published a press release about the event this morning:
Let’s take a closer look at what the AWI had to say:
On 8 February 2023, at 2.20 million square kilometres, the Antarctic sea ice extent had already dropped below the previous record minimum from 2022 (2.27 million square kilometres on 24 February 2022). Since the sea ice melting in the Antarctic will most likely continue in the second half of the month, we can’t say yet when the record low will be reached or how much more sea ice will melt between now and then,” says Prof Christian Haas, Head of the Sea Ice Physics Section at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), with regard to the current developments in the Antarctic. “The rapid decline in sea ice over the past six years is quite remarkable, since the ice cover hardly changed at all in the thirty-five years before. It is still unclear whether what we are seeing is the beginning of a rapid end to summer sea ice in the Antarctic, or if it is merely the beginning of a new phase characterised by low but still stable sea ice cover in the summer.”
Here’s how that news looks in the AWI’s official press release:
By way of prognostication here too is the current JAXA AMSR2 concentration map:
There are some low concentration areas which suggest further extent reductions still to come, despite the recent uptick in the high resolution graph.
Getting back to the AWI’s text:
The melting has progressed since December 2022, especially in the Bellingshausen and Amundsen Seas in the West Antarctic; the former is virtually ice-free. That is also where the research vessel Polarstern currently is, exploring the evidence left behind of past glacials and interglacials. According to expedition leader and AWI geophysicist Prof Karsten Gohl, who is now in the region for the seventh time, having first come in 1994: “I have never seen such an extreme, ice-free situation here before. The continental shelf, an area the size of Germany, is now completely ice-free. Though these conditions are advantageous for our vessel-based fieldwork, it is still troubling to consider how quickly this change has taken place.”
Analyses of the current sea ice extent, conducted by the Sea Ice Portal team, show that, for the entire month of January 2023, the ice was at its lowest-ever extent recorded for the time of year since the beginning of record-keeping in 1979. The monthly mean value was 3.22 million square kilometres, ca. 478,000 square kilometres (an area roughly the size of Sweden) below the previous minimum from 2017. With regard to its long-term development, the Antarctic sea ice shows a declining trend of 2.6 percent per decade. This is the eighth consecutive year in which the mean sea-ice extent in January has been below the long-term trend.
But what has caused the current lack of Antipodean sea ice? The press release continues:
This intense melting could be due to unusually high air temperatures to the west and east of the Antarctic Peninsula, which were ca. 1.5 °C above the long-term average. In addition, the Southern Annular Mode (SAM) is in a strongly positive phase, which influences the prevailing wind circulation in the Antarctic. In a positive SAM phase (like today), a low-pressure anomaly forms over the Antarctic, while a high-pressure anomaly develops over the middle latitudes. This intensifies the westerly winds and causes them to contract toward the Antarctic. As a result, upwelling of circumpolar deep water on the continental shelf intensifies in the Antarctic, promoting sea-ice retreat. More importantly, it also intensifies the melting of ice shelves, an essential aspect for future global sea-level rise.
The press release concludes:
Historical records also reflect the tremendous changes. For example, in the Antarctic summer 125 years ago, the Belgian research vessel Belgica was trapped in the massive pack ice for more than a year – in exactly the same region where the Polarstern can now operate in completely ice-free waters. The photographs and diaries of the Belgica’s crew offer a unique chronicle of the ice conditions in the Bellingshausen Sea at the dawn of the industrial age, which climate researchers often use as a benchmark for comparison with today’s climate change.
Belgica became ice bound near Peter I island on February 28th 1898. On board was second officer Roald Amundsen. The leader of the expedition, Adrien de Gerlache, published a French language book about the voyage in 1902: “Quinze mois en Antarctique“.
JAXA Antarctic sea ice extent is now down to 2.06 million km². Accompanied by a significant fall in Arctic extent, JAXA’s flavour of global sea ice extent has now also reached the lowest level ever recorded in the satellite era, at 15.51 million km² :
P.S. The NSIDC’s 5 day averaged extent hasn’t quite reached a record minimum yet:
However their daily extent has reached a new satellite era record minimum:
[Edit – February 14th]
The NSIDC’s 5 day average Antarctic sea ice extent metric has duly reached a new record low level of 1.91 million km² :
P.S. The NSIDC has now published itsown article about the record minimum:
With a couple more weeks likely left in the melt season, the extent is expected to drop further before reaching its annual minimum. Much of the Antarctic coast is ice free, exposing the ice shelves that fringe the ice sheet to wave action and warmer conditions…
Extent has tracked well below last year’s melt season levels since mid-December. As noted in our previous post, a positive Southern Annular Mode has led to stronger-than-average westerly winds. Along with a strong Amundsen Sea Low, the weather conditions have brought warm air to the region on both sides of the Antarctic Peninsula. This has largely cleared out the ice cover in the Amundsen and Bellingshausen Seas, and reduced the sea ice extent in the northwestern Weddell Sea. Sea ice is patchy and nearly absent over a long stretch of the Pacific-facing coastline of Antarctica. Earlier studies have linked low sea ice cover with wave-induced stresses on the floating ice shelves that hem the continent, leading to break up of weaker areas.
Antarctic sea ice extent has been highly variable over the last several years. While 2022 and 2023 have had record low minimum extent, four out of the five highest minimums have occurred since 2008. Overall, the trend in Antarctic minimum extent over 1979 to 2023 is near zero. The current downward linear trend in the Antarctic minimum extent from 1979 to 2023 is 2,400 square kilometers per year, or 0.9 percent per decade, which is currently not statistically significant. Nevertheless, the sharp decline in sea ice extent since 2016 has fueled research on potential causes and whether sea ice loss in the Southern Hemisphere is developing a significant downward trend.
A new month has arrived, and during January several Arctic sea ice metrics have been drifting towards the bottom of their respective decadal ranges. To begin with here is AWI’s high resolution AMSR2 extent graph, which is currently very close to being lowest for the date in the AMSR2 record:
However that is less the case for area:
Taylor is keen to see the PIOMAS volume data for January, but whilst we wait for the latest Polar Science Center update here is the CryoSat-2/SMOS volume graph, which now includes a couple of month’s worth of reanalysed results as well as more recent near real time numbers:
Here too is the start of month CS2/SMOS thickness map:
At the beginning of the New Year all the central regions of the Arctic are now refrozen apart from a small area of the Kara Sea:
Most Arctic sea ice metrics are near the middle of their respective ranges over the last decade. By way of example, here is a graph of Arctic Freezing Degree Days based on the Danish Meteorological Institute’s temperature data for the area north of 80 degrees latitude:
A change is allegedly as good as a rest, so here’s an alternative view of high resolution AMSR2 area and extent created using the experimental tools provided by the AWI’s Lars Kaleschke at: https://sites.google.com/view/sea-ice/
After a brief pause mid-month the refreeze has accelerated again. Both metrics are in the upper half of the decadal range, with extent this year just above 2021 and area just below last year.
Next let’s take a look at sea ice concentration at the end of October:
Recently Judith Curry published a series of articles on the topic of blackouts. Since attempting to prevent such things is my “professional” speciality I’ve spent a bit of time over at “Climate Etc.” recently. Hence I couldn’t help but notice Judith’s article on Tim Palmer‘s new book, entitled “The Primacy of Doubt”. According to Judith:
This book is a physics-intellectual feast. Must read.
Hence I immediately rushed online and bought a copy from amazon.co.uk, which arrived today. A more detailed overview will follow once I’ve had a chance to read the whole book, but leafing through it this evening I couldn’t help but notice this quotation from Richard Feynman at the very start:
Our freedom to doubt was born of a struggle against authority in the early days of science. It was a very deep and strong struggle. Permit us to question — to doubt, that’s all — not to be sure.
My gaze also alighted on the final paragraph of chapter 10 – “Decisions! Decisions!”:
Just as with weather prediction, a cost-loss analysis can help you make a decision about whether to take anticipatory action regarding climate change…
Based on the way we value our own existence in other areas of life, there does indeed seem to be a strong argument that we should act now, uncertainties about future climate change notwithstanding.
But this is ultimately a decision which each of us must make, e.g. in deciding which politicians to vote for.
Of course being a citizen of the once Great British banana republic I don’t get to vote on our next Prime Minister!
I think I’ll go and pass this news on to Judith and her denizens forthwith. Meanwhile here’s a quotation from the back cover. According to Suki Manabe, winner of the 2021 Nobel Prize in Physics:
The Primacy of Doubt is an important book by one of the pioneers of dynamical weather prediction, indispensable for daily life, describing how the approach can be used for prediction in other areas, such as climate, health, economy, and conflict.
[Edit – October 22nd]
I’m still rather busy trying to help keep the UK’s lights on, so I have yet to even begin reading “The Primacy of Doubt” from cover to cover. However here is another brief extract, from the chapter on “Climate Change”:
We understand these [water vapour, albedo] feedback processes reasonably well. However, there is another feedback process associated with water that we understand rather poorly. This is the cloud feedback process.
[Edit – October 25th]
Here’s another extract from chapter 6 (page 115):
The question of whether clouds act as a positive or negative feedback on climate change can’t at present be answered unambiguously: indeed, I would say it is the biggest unsolved problem in physical climate-change science.
Watch this space!
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