Tag Archives: Zack Labe

The 2025 Maximum Arctic Sea Ice Extent

News, , , , ,

The time has arrived to start taking a close look at the assorted different Arctic sea ice extent metrics, in order to ascertain their respective maxima for 2025. To begin with here’s Zack Labe’s overview of previous years’ maxima:

It now seems highly likely that 2025’s maximum extent will ultimately prove to be the lowest in the satellite era. The remaining question is when this year’s maximum will occur.

My speculation yesterday that AWI’s flavour of Arctic sea ice extent had already achieved its maximum value for 2025 has been negated today:

The NSIDC 5 day average and JAXA extent metrics are also currently at their maximum levels for the year so far, so let’s wait and see which one is the first to take a downward turn.

[Update – March 28th]

The National Snow and Ice Data Center have called the maximum extent of Arctic sea ice for 2025:

On March 22, Arctic sea ice likely reached its maximum extent for the year, at 14.33 million square kilometers, the lowest in the 47-year satellite record. This year’s maximum extent is 1.31 million square kilometers below the 1981 to 2010 average maximum of 15.64 million square kilometers and 80,000 square kilometers below the previous lowest maximum that occurred on March 7, 2017.

Continue reading The 2025 Maximum Arctic Sea Ice Extent →

The 2024 Arctic Sea Ice Minimum Extent

Extent, , , , , , , ,

The 2024 Arctic sea ice minimum extent will almost certainly occur at some point over the next month. The exact date and level will vary from one extent metric to the next. Here’s a comparison of the current JAXA extent with previous minima, courtesy of Zack Labe:

Here too is a more detailed look at 2024 extent compared with the 5 lowest annual minima in the JAXA record:

By way of comparison, here is the equivalent graph for the OSI SAF extent metric, which experienced an up tick yesterday but has now reached a new low for the year:

The Alfred Wegener Institute’s extent metric has flatlined over the last two days:

However AWI Arctic sea ice area is currently falling, which may well presage further significant falls in extent:

The NSIDC web site is currently “experiencing technical difficulties”, but hopefully we’ll be able to take a look at their extent graph in the very near future.

[Update – September 4th]

The NSIDC web site is back in action, and their 5 day averaged extent metric is currently still falling quickly:

The ARCUS Sea Ice Prediction Network August report has been published. Note that the predicted numbers are for the September monthly average extent rather than the daily minimum:

For the August Outlook, we received 24 contributions of September pan-Arctic sea-ice extent forecasts…

The August 2024 median forecasted value for pan-Arctic September sea-ice extent is 4.27 million square kilometers with an interquartile range of 4.11 to 4.54 million square kilometers. This is about 200,000 square kilometers lower than the June median and about 250,000 square kilometers lower than the July median, which reflects the faster than average ice loss during July.

The lowest sea-ice extent forecast is 3.71 million square kilometers and the highest sea-ice extent forecast is 5.23 million square kilometers. These extremes are actually higher, particularly on the low end, than the estimates from July.

[Update – September 9th]

There’s been the tiniest of upticks in the NSIDC 5 day extent metric. 1 thousand km² to be precise. However, the others are still slowly declining:

[Update – September 10th]

NSIDC extent has posted a new low for the year, and JAXA extent is still declining. However there has been a slightly more substantial uptick in the OSI SAF metric:

The current minimum is 4.64 million km² on September 8th.

AWI sea ice area has posted a convincing looking minimum on September 4th, which suggests that the central refreeze is already well under way:

[Update – September 17th]

JAXA/ViSHOP/ADS extent has risen significantly over the last two days:

It now looks highly likely that the 2024 minimum will prove to be 4.07 million km² on September 13th. That is 4th lowest for the date, but equal 5th lowest minimum in the JAXA record.

A closer look at some of the other extent metrics will have to wait until this problem is solved:

Not good timing for a data outage!

[Update – September 22nd]

SSMIS data has been flowing again for a couple of days:

This graph may be subject to revision if and when the missing data is recovered, but currently it looks as though the 2024 minimum of the NSIDC 5 day averaged extent metric is 4.28 million km² on September 11th.

[Update – September 24th]

The National Snow and Ice Data Center formally announced today that:

On September 11, Arctic sea ice likely reached its annual minimum extent of 4.28 million square kilometers. The 2024 minimum is the seventh lowest in the nearly 46-year satellite record. The last 18 years, from 2007 to 2024, are the lowest 18 sea ice extents in the satellite record…

Note that this is a preliminary announcement. Changing winds or late-season melt could still reduce the Arctic ice extent, as happened in 2005 and 2010. NSIDC scientists will release a full analysis of the Arctic melt season, and discuss the Antarctic winter sea ice growth, in early October.

The NSIDC also addressed the recent missing SSMIS data issue mentioned above as follows:

Note that a gap exists in the input source data between September 12 and September 18. This gap somewhat lowers our confidence in the minimum extent estimate. However, it appears that September 11 is the mostly likely date of the minimum based on data trends in daily extent values leading up to the 5-day average on September 11 and the extent values after data restarted on September 18. If extent did drop further between September 11 and September 18, it would have been marginal. If the input source data becomes available to fill that gap, our team will update the minimum estimate if necessary.

Watch this space!

The 2023 Arctic Sea Ice Minimum Extent

News, , , , , , , , , , ,

It’s that time of year again! Tony Heller has been asserting that “summer is over at the North Pole” for several weeks now, and the 2023 Arctic sea ice minimum extent will occur at some point over the next four or five weeks. The exact date and level will almost certainly vary from one extent metric to the next.

To get the minimum extent ball rolling, here’s Signe Aaboe’s graph of previous summer minima based on OSI SAF data:

Here too is Zack Labe’s equivalent, based on JAXA data:

Continue reading The 2023 Arctic Sea Ice Minimum Extent →

The 2023 Maximum Arctic Sea Ice Extent

News, , , ,

March has arrived, so it’s time to start taking a serious look at where and when the 2023 maximum Arctic sea ice extent will occur.

To start with here’s Zack Labe’s overview of previous years’ maxima:

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:

[Edit – March 16th]

They are of course a bit late with the news, but the NSIDC have now called the 2023 maximum Arctic sea ice extent:

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.

Watch this space!

The 2022 Arctic Sea Ice Minimum Extent

Extent, , , , , ,

September has arrived and it’s time to start speculating about when and at what level this summer’s minimum Arctic sea ice extent will occur. Here’s a helpful summary of previous years’ JAXA AMSR2/AMSR-E extent minima courtesy of Zack Labe:

Here too is JAXA’s current graph of extent, including a selection of previous years:

JAXA extent on August 31st was 4.96 million km2, marginally below last year’s value of 4.99 million km2 on the same date.

Continue reading The 2022 Arctic Sea Ice Minimum Extent →

The 2021 Maximum Arctic Sea Ice Extent

Extent, , , , , , , , , ,

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!

Continue reading The 2021 Maximum Arctic Sea Ice Extent →

The 2020 Maximum Arctic Sea Ice Extent

Extent, , , , , , , , ,

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:

On February 25, 2015, Arctic sea ice extent appeared to have reached its annual maximum extent, marking the beginning of the sea ice melt season. This year’s maximum extent not only occurred early; it is also the lowest in the satellite record. However, a late season surge in ice growth is still possible.

Each year we keep track of the assorted Arctic sea ice metrics over the next month or so, and they rarely agree on the date of maximum extent, and never agree on the sea ice extent on that date! The reason for that is explained in a 2017 paper entitled “Variability and trends in the Arctic Sea ice cover: Results from different techniques“:

Reports on the sea ice cover have been provided by different institutions using basically the same set of satellite data but different techniques for estimating key parameters such as ice concentration, ice extent, and ice area. In this study, a comparison of results from four different techniques that are frequently used shows significant disagreements in the characterization of the distribution of the sea ice cover primarily in areas that have a large fraction of new ice cover or significant amount of surface melt.

In due course we’ll look at the metrics from a variety of different institutions, but let’s start with JAXA, comparing 2020 with 2015 and the 2010s average:

Extent is clearly increasing just at the moment! Will the next peak prove to be the maximum for the year or will we have to wait another month or more to find out that value, as suggested by the average?

Compare and contrast JAXA extent with Wipneus’ high resolution AMSR2 extent and area:

Perhaps the 2020 maximum area has already been reached?

[Edit – February 25th]

Or perhaps not! We’re playing mix and match this morning, since Wipneus’s new numbers haven’t been released yet. Here UH AMSR2 high resolution Arctic sea ice area from February 23rd:

Plus JAXA extent for the 24th:

[Edit – February 27th]

Tony Heller’s latest sea ice themed article claims “Normal Sea Ice Extent At Both Poles”. Hence today’s JAXA extent graph includes the averages for previous decades:

Extent is evidently increasing once again, and is even more evidently well below what passed for “normal” in the twentieth century!

Let’s also compare the Pacific periphery:

with the Atlantic side of the Arctic Ocean:

The Bering and Okhotsk Seas will be sea ice free by the time September 2020 arrives. How about the Kara, Barents and particularly Greenland Seas though?

[Edit – February 29th]

Arctic sea ice maximum volume usually occurs in April, but nonetheless let’s keep an eye on the metric that most nearly measure the “amount” of sea ice left in the Arctic in 2020. Here’s our “measured” CryoSat-2/SMOS volume metric, using reanalysed data up to February 12th:

PIOMAS “modelled” volume for February should be released soon, but getting back to extent the JAXA flavour has been setting new highs over recent days:

whereas the NSIDC’s Charctic 5 day averaged extent has not!

[Edit – March 6th]

Here’s the February PIOMAS gridded Arctic sea ice thickness map, courtesy of Wipneus on the Arctic Sea Ice Forum:

plus the traditional modelled volume graph:

As angech has pointed out elsewhere, according to the PIOMAS team:

CryoSat-2 data show total volume for February 2020 substantially lower than PIOMAS with 2020 Febuary near record low levels over the 2011-2020 period

[Edit – March 19th]

The March mid month PIOMAS numbers have been crunched by Wipneus. Here’s how things look at the moment:

For comparison purposes here’s the current CryoSat-2/SMOS Arctic sea ice thickness map:

[Edit – March 20th]

After flatlining for a long time JAXA extent has posted significant declines for two days running. There’s been no official announcement from the NSIDC as yet, but it now seems safe to conclude that there won’t be a late surge in extent similar to 2010. Here’s the current JAXA graph:

plus NSIDC’s 5 day averaged extent:

Hence the (still provisional!) maximum numbers for 2020 are:

JAXA/VISHOP AMSR2 – 14.45 million square kilometres on March 3rd
NSIDC 5 day SSMIS – 15.05 million square kilometres on March 5th

The University of Hamburg’s JAXA AMSR2 concentration data seems to have suffered an outage over the crucial period. Hopefully the gaps will be filled in due course. However more recent regional graphs  reveal the following:

The recent declines in overall extent are evidently driven by declines on the Pacific periphery.

Facts About the Arctic in January 2019

Thickness, , , , , , , , , , , , , ,

We generally write our periodic reports on the state of Arctic sea ice around the time the PIOMAS volume numbers are published. It seems as though we’ll have a long wait for that to happen at the moment though. According to The Economist today:

America’s government shutdown has become the longest in history. Hundreds of thousands of federal workers remain either stuck at home or forced to work without pay. To reopen the government President Donald Trump is demanding $5.7bn for his border wall. Nancy Pelosi, who presides over the most polarised House of Representatives in recent memory, does not want to give it to him.

and according to the Polar Science Center at the University of Washington:

Due to the US Government Shutdown, PIOMAS ice volume and thickness data which depend on federal government generated reanalysis products, are currently not updated.

Instead of PIOMAS, let’s start instead with the January 2019 edition of the National Snow and Ice Data Center’s Arctic Sea Ice News:

As 2018 came to a close, Arctic sea ice extent was tracking at its third lowest level in the satellite record, while sea ice in the Antarctic remained at historic lows. Slightly faster growth in the first few days of the new year, mostly in the Pacific sea ice areas, has the daily sea ice extent at fifth lowest as of this post.

Now let’s take a look at our favourite high resolution AMSR2 area and extent metrics:

You can see that towards the end of December Arctic sea ice extent was verging on lowest for the date, since when it has risen quickly to reach highest for the date in the brief AMSR2 records a few days ago.

The NSIDC also mention the US Government shutdown:

Unfortunately, as a result of the partial government shutdown, we are unable to access the National Oceanic and Atmospheric Administration (NOAA) pages to retrieve information on atmospheric air temperatures and sea level pressure patterns. Instead, we turn to daily (2 meters above the surface) mean air temperatures north of 80 degrees North from the European Centre for Medium-Range Weather Forecasts (ECMWF) operational model. This analysis shows that air temperatures remained above the 1958 to 2002 average for all of December.

Graph by Zack Labe
Graph by Zack Labe

That brings us on to our Arctic freezing degree days graph, based on DMI data:

After a very slow start to the freezing season the FDD numbers are now vying for second place with last year, behind the astonishingly warm winter of 2016/17. In the absence of the PIOMAS volume numbers we can at least take a look at sea ice thickness. Here’s CryoSat-2:

followed by SMOS:

and since a change is as good as a rest here’s the latest map from the Russian Arctic and Antarctic Research Institute for good measure:

All those sources seem to be agreed that large areas of both the Barents and Kara Seas are currently covered by young thin ice. Finally, for the moment at least, let’s take a look at some extracts from the NSIDC’s review of 2018:

January 2018 began the year with record low sea ice extents for the Arctic as a whole.

The seasonal maximum, reached on March 17, 2018, was the second lowest in the satellite record. While low extent persisted through April and May, sea ice loss during early summer was unremarkable despite above average 925 hPa air temperatures over the Arctic Ocean and Eurasia.

Air temperatures over the Arctic Ocean in July were below average, followed by above average temperatures in August. In fact, on average, August temperatures were higher than July temperatures in 2018. This is highly unusual in the Arctic and something not seen in at least 40 years.

The September 2018 seasonal minimum extent ended up slightly above the long-term linear trend line, tying with 2008 for the sixth lowest in the satellite record. After the minimum, the ocean was slow to freeze up, and October sea ice extent ended up as the third lowest. However, ice growth was very rapid in November, such that November 2018 extent approached the interquartile range of the 1981 to 2010 median. Nevertheless, large amounts of open water remained in the Barents and Chukchi Seas. By the end of December, ice conditions in the Chukchi Sea were back to average, while extent remained unusually low in the Barents Sea.

Coverage of old ice (greater than 4 years old) over the Arctic continued to decline. Such old ice covers only 5 percent of the area it used to in 1980s.

 

[Edit – January 13th]

Arctic sea ice area and extent have both been falling over the last few days, possibly as a result of the recent cyclone which created strong northerly winds in the Fram Strait. This is from Earth at 09:00 UTC on January 10th, showing a MSLP of 946 hPa:

Here’s what used to be referred to as JAXA extent:

Meanwhile up in the stratosphere at 10 hPa the polar vortex has gone into reverse:

Or to be more precise:

The 11th Key Science Moment of 2016

Area, , , , , , , , ,

A brief history of scientific “churnalism” in the age of social media. The “post-truth” of The Guardian’s 11th Key Science Moment of 2016.

On November 7th 2016 we broke this astonishing news on Twitter:

Nobody noticed! Then on November 16th 2016 Zack Labe did likewise:

The story got some legs. Zack got pushback from some “skeptics” and then the AGU blogged about the story.:

My attention was called to this issue last week thanks to the Twitter feed of Zack Labe, a PhD student in Earth Systems Science at the University of California – Irvine. He makes great graphics showing the latest data on polar climate.

Then he got interviewed by the AGU. The AGU linked back to the graphic graphic in question in the clouds at Google, but there was no mention of our November 6th article or the real source of the story. The Arctic Sea Ice Forum (ASIF for short).

It’s now December 18th, and as far as I’m aware that remains the case in the mainstream media (MSM for short). The Arctic Sea Ice Forum grew out the earlier Arctic Sea Ice Blog (ASIB for short). The proprietor of both the ASIB and ASIF has been revealed by CBC to be one Neven Curlin. They recently interviewed Neven, and even gave him top billing above Sir David Attenborough in the resulting podcast:

‘Like watching a train wreck’: Blogger quits writing about climate change

However the title of the CBC article is inaccurate, as CBC would surely have noticed if they’d read Neven’s article on the ASIB on the topic of his “sabbatical”.

Sabbatical (I hope)

Now comes news that the “astonishingly low level” of global sea ice area that we brought to the waiting world’s attention on November 7th has today been chosen by The Guardian as one of their:

12 key science moments of 2016

The story outlined above and the associated graphic graphic are conspicuous only by their absence, but the Grauniad have thoughtfully provided this pretty stock photo of some sea ice:

Scroll down the Guardian’s article to number 11, pausing to read Tamsin Edwards’ section on atmospheric carbon dioxide levels at number 9 on the way down (unlike CO₂ concentrations). There you will discover Professor Andrea Sella’s opinion that:

In October, unprecedented weather patterns drove icy winds across Siberia, pushing Arctic temperatures up to 20C above normal and parts of the Arctic Ocean failed to refreeze; in the Antarctic, sea ice thawed faster than usual. For me the bombshell came from a Dutch blogger in late November: a plot of the Arctic plus Antarctic showed sea ice this autumn to be tracking 4m km2 (the size of western Europe) below the normal average. This is a 7-sigma event – with a chance of about one in a hundred billion of being random. The ice doesn’t lie. If we don’t take this seriously now, our children will ask us why.

The “plot of the Arctic plus Antarctic” Andrea refers to was created by “Wipneus”, who I suppose could reasonably be described as a “Dutch programmer”. Neven could reasonably be described as a blogger, although he is much more than that. Although he was born in The Netherlands he no longer lives there.

Here’s the current state of play:

nsidc_global_area_20161215-400

Are your children asking “Why?” yet?

Should anybody wish to pose that question on Twitter please see: