If the new satellite data are to be trusted, sea ice has retreated rapidly this month and now sits far below the 1981-2010 normal; it looks like the anomaly is between 3 and 4 standard deviations, which is huge. The previous record lowest extent was observed in (September) 2012 and this year's ice is far less extensive than 2012 at this date. This doesn't mean 2016 is guaranteed to see a new record minimum, but I'd guess the seasonal rate of melt would have to be remarkably slow from here on out to avoid a new record.
Here's a similar figure from the Danish Meteorological Institute; they are using the same satellite data as NSIDC, so it's not surprising the charts look similar.
The PIOMAS model of Arctic sea ice shows that estimated ice volume grew uncharacteristically slowly in the first 4 months of the year and was far below normal at the end of April.
There won't be any prizes for guessing why ice growth was so anemic this winter; it was undoubtedly related to the extreme warmth around the Arctic basin. To illustrate this, I created maps of monthly temperature anomaly from November through April, using both the station data and the gridded reanalysis (model) data - see below, and note that the color scales are the same (click to enlarge the maps). I like to think of the left-hand maps as the "ground truth", as they're based on station measurements, but the reanalysis gives a generally credible picture of conditions over the Arctic ocean itself.
Note the amazingly strong and persistent warm anomaly in the northern Barents Sea, a direct result of the abnormal lack of sea ice. This anomaly might be a bit overdone by the reanalysis model, but perhaps not by much. There is an observatory on one of the islands in Franz Josef Land, and their mean November-March temperature was 12.4°F, compared to an estimated 1981-2010 normal of -6.6°F, for a 5-month mean anomaly of +19°F. (This station doesn't show up on the maps because I required 28 years of data to calculate the normals, but this station only had 24.)
Finally here's the ECMWF model-estimated 2m temperature north of 80°N so far this year, courtesy of the Danish Meteorological Institute. It would appear that not a single day has been cooler than the 1958-2002 normal.
Is The USA the only country with a satellite-based monitoring program for sea ice? Surely someone (Japan/China/Russia) has eyes above for environmental purposes? They all comment regarding changes in climate.ReplyDelete
Examples from just a brief search:
Gary, undoubtedly many other nations keep track of sea ice, and I know there is (at least) independent Japanese satellite data, but public accessibility of summarized real-time results seems to be a challenge. If you find anything directly comparable to the NSIDC products, I'd be very happy to learn of it.Delete
Just some potential links. Didn't register for data download.Delete
NSIDC and IRAC JAXA sea ice estimates:
There's more but maybe this is of some initial value. I wouldn't like to infer the accuracy of the data presented without actual calibration via observation. But I get skeptical when sensors change or are cross compared between sources. Too much risk of saying what's only an estimate is fact and grist for the world media.
Another interesting local UAF link relative to sea ice. Lots to explore here:Delete
The Arctic Basin offers the perfect example of atmosphere/ocean chicken and egg. There's a lack of sea ice because it's warm, and it's warm because there's a lack of sea ice.ReplyDelete
Andy, great point - I agree. And I suspect that sea ice variability may also be significantly influenced by subsurface ocean temperature changes (e.g. North Atlantic currents), which are not well-understood.Delete
Gary - thanks for the links.
Once we figure out what's 'normal' it may be resolved. Until then about all we can do is observe and report. The Earth's been changing for quite some time.ReplyDelete
Estimated Earth climate over 18,000 years?Delete
A good reference, thanks!Delete
Also see for a classic discussion of Alaskan geology and climate:Delete
Pewe. 1975a. Quaternary geology of Alaska. Estimates of historic climate from p. 103:
Pewe. 1975b. Quaternary stratigraphic nomenclature in unglaciated central Alaska: