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.
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:
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:
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.
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!
