Arctic Ice: Then and Now

July 24, 2014

DailyClimate:

The impacts are increasingly being felt everywhere – bigger storms in the Midwest, soggy summers in England, drought in Colorado. But nowhere on the planet are the impacts as dramatic as the Arctic, and the ice cap is a prime example.

If you’re sweltering in New York or Miami or Los Angeles, the only ice you’re probably thinking about is the stuff melting fast in your drink.

But up in the Arctic, the ice pack is on pace for another record low. Scientists won’t know for sure until mid-September, the end of the North’s melt season. But two snapshots, one from July 21, 1979, the other from July 21, 2014, show the change.

Below, time lapse of Antarctic September Sea ice extent from 1979.

And here, changes in Arctic (northern) sea ice during the same 1979 to 2012 period.

NSIDC graph current as of 07/24/14

nsidc0714

 

National Snow and Ice Data Center:

During the second half of June, the rate of sea ice loss in the Arctic was the second fastest in the satellite data record. As a result, by the beginning of July extent fell very close to two standard deviations below the long-term (1981 to 2010) average.

Below, Danish maps of Arctic Ice from observations, which date from the turn of the 1900s.

Poster FrankD on Skeptical Science:

Danske Meteorologiske Institut published a series of annual reports on arctic sea ice covering most years from 1893 to 1956. The link has one folder per year, with each containing individual pages (month identified by the trailing digit) and the whole annual report (about 5 meg each).

Just referring to August extent…

Its true that ice extent was lower in the 1930s than it had been in the preceding 30 years. In particular, 1938 saw a dramatic reduction from the previous years – it was probably 1.4 M km^2 below the then long term average and maybe 0.6 M km^2 below the already low years in the late 30′s (carefully measured using Eyeball, Mk I).

So, it is fair to say there were some big melts in the 30′s. But Christy’s false equivalence is an epic fail – “similar melts” is pretty nice weasel-wording for mine. 1.4 M km^2 below recent climatology? Considered like that, 1938 was like 2010, I guess.

But in absolute terms, August 1938 extent was much greater (4 M km^2?) than today. So any attempt to conflate the two is…well…I can[‘t think of an adjective suitable for polite company.

Taking the Kinnard graphic (below) – the 1930′s “similar melt” is the second last dip on the graph, the first decline with modern observational data. This saw a return to “normal” after a peak that had seen the greatest extents in 500 years.

Compared to the current decline on Kinnard (even without “enhancement”)? Well, even on Sesame Street they could tell you when one of these things was not like the other…

Below, August 1938, a very low year, compared to August 2012.

2 Responses to “Arctic Ice: Then and Now”


  1. […] DailyClimate: The impacts are increasingly being felt everywhere – bigger storms in the Midwest, soggy summers in England, drought in Colorado. But nowhere on the planet are the impacts as dramatic…  […]

  2. John Says:

    Reblogged this on jpratt27.


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