No Surprises: Sea Ice Continues Historic Downward Slide

October 7, 2014

Here’s your all purpose handy dandy recap of the current arctic melt season, just concluded.

National Snow and Ice Data Center press release:

Sea ice covering the Arctic Ocean melted to its sixth lowest extent this year, while sea ice surrounding the Antarctic continent continued to break winter records, according to scientists at the National Snow and Ice Data Center (NSIDC).

Arctic sea ice cover grows each winter as the sun sets for several months, and shrinks each summer as the sun rises higher in the northern sky. Each year, the Arctic sea ice reaches its minimum extent in September. Summer sea ice extent is important because, among other things, it reflects sunlight, keeping the Arctic region cool and moderating global climate.

At the end of its melt season, Arctic sea ice fell to the sixth lowest extent in the satellite record, both in the daily and monthly average. Sea ice hit 5.02 million square kilometers (1.94 million square miles) on September 17 and averaged 5.3 million square kilometers (2.05 million square miles) for the month of September.

“Twenty years ago, having ice extent this low would have astounded us,” said NSIDC Director Mark Serreze. “Now it is expected.”

This year edged out last year as the sixth lowest extent since satellites started measuring sea ice in 1979. The lowest Arctic extent on record occurred in 2012, when sea ice measured 3.41 million square kilometers (1.32 million square miles). The succeeding lowest years are 2007, 2011, 2008, and 2010.

NSIDC has discussed how sea ice long term decline has been documented in the pre-satellite era:

To look back into the past, researchers combine data and records from indirect sources known as proxy records. Researchers delved into shipping charts going back to the 1950s, which noted sea ice conditions. The data gleaned from those records, called the Hadley data set, show that Arctic sea ice has declined since at least the mid-1950s.  Shipping records exist back to the 1700s, but do not provide complete coverage of the Arctic Ocean.  However, taken together these records indicate that the current decline is unprecedented in the last several hundred years.

arcticice1953_3

Other longer term records exist as well, such as a nice series of ice maps from the Danes, who, historically, know a thing or two about ice. Below is from 1938 – the whole series, from 1893 to 1956,  is available here:

1938_08
Arctic Sea Ice Blog:

“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.”

2014 press release continued:

Through 2014, Arctic sea ice has now been declining at a rate of 13.3% per decade relative to the 1981 to 2010 average. The ten lowest September ice extents over the satellite record have all occurred in the last ten years.

“This year was nothing surprising. Overall we’re continuing the long-term decreasing trend,” said Walt Meier, research scientist at the NASA Goddard Space Flight Center. “We’re still well below average and there’s no indication that we’re going to recover.”

Below, Walt Meier interviewed a year ago in  December, 2013:

2014 again:

Between the seasonal maximum extent that occurred on March 21, 2014 and the September 17 minimum, the Arctic Ocean lost a total of 9.89 million square kilometers (3.82 million square miles) of ice; which is the ninth largest in the satellite record, but the least amount of seasonal loss since 2006. This year’s loss was 1.92 million square kilometers (741,000 square miles) less than the total loss that occurred in 2012.

Long term reconstruction of arctic ice extent

Weather conditions prevailing over the summer of 2014 were unremarkable. The one significant weather pattern over the summer was a larger than normal pressure gradient over the Laptev Sea that drove southerly winds, brought warmer air and helped drive sea ice northward. This led to the tongue of open water that reached to within 5 degrees latitude of the pole. However, this pressure gradient was not particularly extreme so thinner ice cover in the area was also a significant contributor. Sea surface temperatures may also have played a role.

“The fact that minimum ice extent in 2013 and 2014 still fell so low despite ordinary weather suggests that the system has settled into the low trend,” said NSIDC scientist Julienne Stroeve.

Meanwhile, sea ice surrounding the Antarctic continent reached its maximum extent on September 22 at 20.11 million square kilometers (7.76 million square miles). This is 1.54 million square kilometers (595,000 square miles) above the 1981 to 2010 average extent, which is nearly four standard deviations above average. Antarctic sea ice averaged 20.0 million square kilometers (7.72 million square miles) for the month of September. This new record extent follows consecutive record winter maximum extents in 2012 and 2013. The reasons for this recent rapid growth are not clear. Sea ice in Antarctica has remained at satellite-era record high daily levels for most of 2014.

“What we’re learning is, we have more to learn,” said Ted Scambos, lead scientist at NSIDC.

The unusual sea ice growth in Antarctica might be caused by changing wind patterns or recent ice sheet melt from warmer, deep ocean water reaching the coastline, according to scientists at NSIDC. The melt water freshens and cools the deep ocean layer, and it contributes to a cold surface layer surrounding Antarctica, creating conditions that favor ice growth.

if Aunt Teabag or Uncle Dittohead persist in talking about the supposed significance of Antarctic ice, you can show them these videos.

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.

5 Responses to “No Surprises: Sea Ice Continues Historic Downward Slide”

  1. jimbills Says:

    Thank you for the update.


  2. Some of the link aren’t working. The fourth one, “Poster FrankD on Skeptical Science”, leads to a “file not found” page stating, “There is no page at this address.” The fifth link, “http://www.youtube.com/watch?v=AztEry44A9A]”, has an extra “]” at the end of the hyperlink which causes the youtube link to fail. the sixth link, “2014 again”, links to the same youtube video and has the same problem as the fifth link.

    Thanks for helping to keep everyone up to date on this.

    Regards,
    M. Tilbrook


  3. An excellent summary, best collection on the internet.

    In support of the denialists, The Arctic summer ice and Antarctic winter ice reflects the same amount of sunshine, just different properties: sunlight for the Arctic summer ice and sundark for the Antarctic winter ice. Like dark energy and dark matter, dark sunshine cannot be seen directly with eye. It is inferred from their cognitive dissonance.


  4. An excellent summary, best collection on the internet.

    In support of the denialists, The Arctic summer ice and Antarctic winter ice reflects the same amount of sunshine, just different properties: sunlight for the Arctic summer ice and sundark for the Antarctic winter ice. Like dark energy and dark matter, dark sunshine cannot be seen directly with eye. It is inferred from their cognitive dissonance.


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