Looking Like An Eventful Arctic Summer For Ice Loss - Just Crossed The 2012 Record Line

[hatrack]

Link to tweet

After a winter of record low sea ice growth, Arctic ice is well into the range for a record summer melt.

Bob Henson in WeatherUnderground:

The Arctic Ocean’s coating of sea ice—now remarkably thin and sparse after a record-warm winter—could plummet by late summer to the lowest extent in 38-plus years of observations. Weather conditions over the next few weeks will determine just how much melting ultimately occurs. However, the ice is so depleted that even a melt season from here on that’s average by recent standards could leave the ice at a record-low extent.

Thus far, the 21st century has seen two grand dips in Arctic sea ice extent, in 2007 and in 2012. In both cases, the ice saw a modest but incomplete recovery, and the 38-year observation period can be easily split into “before” and “after”: each year after 2007 has seen a lower minimum than each year beforehand.

The sorry state of Arctic sea ice right now isn’t readily apparent if you look only at extent (the amount of ocean covered by at least 15%concentration of ice). On Wednesday, the National Snow and Ice Data Center reported that Arctic sea ice extent in May was the fourth lowest on record. That brought an end to the string of record-low monthly values set or tied in January, February, March, and April. Colder-than-usual weather at high latitudes helped keep the ice extent from shrinking in May as much as it typically does.

EDIT

If the Beaufort high intensifies in tandem with low surface pressure over high latitudes of Eurasia, it can lead to a setup dubbed the Arctic rapid change pattern, or dipole anomaly, which exerts a double whammy on sea ice: pulling warm air north to attack sea ice on the Pacific side of the Arctic, and pushing sea ice on the Atlantic side toward lower latitudes.

Later in the summer, your recipe might include some big Arctic cyclones to generate high winds that fragment the weakened ice, thus allowing even more of it to melt. Here, NASA video shows how an August cyclone in the arctic contributed to the breakup and dissolution of Arctic ice extent and a record low year.

EDIT

https://climatecrocks.com/2017/06/13/arctic-sea-ice-setup-for-a-new-record-low-summer/#more-46158

[muriel_volestrangler]

1. On the other hand, melt ponds appear to be comparatively low

The Weather Underground guy points out "melt ponds atop the ice surface are key at this time of year", and, from Neven's Arctic Sea Ice blog:

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I've been in contact with Dr David Schröder from the University of Reading and he has confirmed (or rather his model) that this year (again) there is less melt pond formation than in years with low minimums. Below is a comparison of 2012, 2013, 2016 and this year:

Caveat: This is a model result, and so the distribution of melt ponds doesn't necessarily reflect reality.

As you can see, according to the model, there are even fewer melt ponds than last year. In fact, it looks very similar to 2013. Dr. Schröder wrote to me in an e-mail:

"We predict the September Arctic sea ice extent 2017 to be slightly larger than last year: 5.0 +/- 0.5 mill. km2. In spite of the lowest Arctic ice volume in April, the May melt pond fraction in May is the second lowest of the last 10 years in our simulation with the sea ice model CICE. Anomaly figures with respect to 2006 to 2015 are shown for May 2017, 2016, 2012 (highest pond fraction) and 2013 (lowest pond fraction). Stronger melting and pond formation only occurred north of Canada and some parts of the Beaufort Sea. Otherwise the pond fraction is very similar to May 2013. Below average air temperatures (with respect to 2008 to 2015) and increased snow depth seem to have had a stronger impact in reducing pond formation than the thinner ice in increasing pond formation."

What's nice about this, is that it confirms our suspicions back in February when we discussed what could be the reason there was such a divergence between PIOMAS and CryoSat (as mentioned in the March PIOMAS update). The number one suspect was snow cover, mostly due to the relentless series of storms coming in from the Atlantic. Persisting snow on the ice is the best explanation for the fact that we haven't seen much melt ponding (ice turning blue on satellite images) so far, despite ideal weather conditions during the past two weeks.

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http://neven1.typepad.com/blog/2017/06/melting-momentum-may-2017.html

[hatrack]

2. True, as far as it goes

NSIDC thickness measurements do not look encouraging, though.