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Arctic Ice Trends Since 1864

October 14, 2014
tags: ,

By Paul Homewood

h/t Ron C and Green Sand

There were a couple of comments on my post, HH Lamb & Cooling In The Arctic, which are worth expanding on.

1) First, this paper from Torgny Vinje:

Anomalies and Trends of Sea-Ice Extent and Atmospheric Circulation in the Nordic Seas during the Period 1864–1998

TORGNY VINJE – Feb 2000

ABSTRACT
The extent of ice in the Nordic Seas measured in April has decreased by 33% over the past 135 yr. Retrospective comparison indicates that the recent decrease in the ice extent is within the range of variability observed since the eighteenth century. Temporal, monotonically reduced extreme events occur with intervals of 12–14 yr, suggesting that series longer than 30 yr should be considered to obtain statistical significance regarding temporal changes. Otherwise, decadal temperature variation is also found in the northbound warmer ocean currents. The temperature in the upper layers of these currents seems moreover to have increased by the order of 1C since the cooling during the Little Ice Age. This temperature increase accounts for most of the ice extent reduction since ;1860. A strong negative correlation is found between the larger North Atlantic oscillation (NAO) winter index and the Nordic Seas April ice extent, and a corresponding positive correlation is observed for the Newfoundland–Labrador Sea. It is not until the warming of the Arctic, 1905–30, that the NAO winter
index shows repeated positive values over a number of sequential years, corresponding to repeated northward fluxes of warmer air over the Nordic Seas during the winter. An analog repetition of southward fluxes of colder air during wintertime occurs during the cooling period in the 1960s. Concurrently, the temperature in the ocean surface layers was lower than normal during the warming event and higher than normal during the cooling event. Northward atmospheric winter fluxes are observed after the enhanced global warming after ;1970, and, for the first time over the period considered, a positive correlation is observed between atmospheric and oceanic reducing effects on the ice extent. The enhanced global warming over the past two decades seems also to be manifest in an intensified winter circulation at higher latitudes, rather than a contemporary change in the Arctic ocean surface temperature.

http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442%282001%29014%3C0255%3AAATOSI%3E2.0.CO%3B2

Vinje presents these graphs of April sea ice extent trends:

image

image

As well as the long term declining trend since 1860, they highlight:

1) The large drop in extent between 1860 and 1900.

2) The low level of extent by 1940, pretty much comparable to 2000.

3) The rapid expansion of ice, particularly in the Western sector, during the 1960’s, and again in the late 1970’s.

They also show changes in August extent, but only since 1920. These follow a similar pattern.

image

In their conclusions, they note:

1) The extent of ice in the Nordic Seas measured in April has been subject to a reduction of ~33% over the past 135 yr. Nearly half of this reduction is observed over the period 1860–1900.

2) While the mean annual reduction of the April ice extent is decelerating by a factor of 3 between 1880 and 1980, the mean annual reduction of the August ice extent is proceeding linearly.

3) The August ice extent in the Eastern area has been more than halved over the past 80 yr. A similar meltback has not been observed since the temperature optimum during the eighteenth century. This retrospective comparison indicates accordingly that the recent reduction of the ice extent in the Eastern area is still within the variation range observed over the past 300 yr.

2) Secondly, this chart from Thor Edward Jakobsson, Project Manager, Sea ice Research Unit at the Icelandic Meteorological Office. This was included in some work he published on sea ice around the coast of Iceland.

Sea ice Fig 4 with caption r&c

http://website.lineone.net/~polar.publishing/seaiceincidents.htm

Not the best of quality, and the original is no better! But Jakobsson adds these comments, which clarify matters.

Sea ice off the Icelandic coasts has been recorded for centuries, first by remarks in annals and diaries kept by farmers and officials, and in a more regular manner during the last couple of centuries. In an effort to find a measure of variability from one year to another, an index was developed indicating the severity of sea ice incident during a particular year along the coasts of Iceland. The index refers both to the extent of the Icelandic coastline being visited by sea ice and number of weeks with recorded sea ice during the year.

Figure 4 shows the sea ice index during most of 20th century. During the first two decades heavy sea ice was quite common along the coasts of Iceland, but in the 1920s a drastic change occurred. Sea ice along the coasts of Iceland became an uncommon characteristic and almost a forgotten phenomena around the middle of the century. An abrupt change occurred in the mid-1960s.

 

 

Both studies bear out HH Lamb’s findings concerning the longer term trends in the Arctic, and show clearly why monitoring trends only since 1979 can be highly misleading.

13 Comments
  1. October 14, 2014 10:04 pm

    Thanks, Paul.
    I show in my climate pages:
    From the University of Bremen, Germany:
    Note that the maximum extent of Arctic sea ice was reached in 1979 and for the Antarctic in 2014.
    The minimum extent of sea ice for the Arctic was in 2007 and for the Antarctic it was in 1993.

    • October 14, 2014 10:20 pm

      I’d notice that the Arctic ice extent has shown important “near to average” values on April, since 2008, with 2012 being a little above average at April-May.

      This, I believe, confirms the idea that the minimum of the Arctic ice was in fact in 2007, in 2012 the ice was already in a dynamical process of recovery.

  2. October 14, 2014 10:04 pm

    Reblogged this on CraigM350.

  3. October 14, 2014 10:17 pm

    Thanks for the interesting post, Paul.

  4. October 15, 2014 3:47 am

    we know for sure that the arctic area [not influenced by the gulfstream] has become significantly cooler,
    my result is -0.055K/annum since 1998 (Average 10 weather stations in Alaska)
    That is almost 1K down since 1998.
    How come nobody but me noticed?

  5. David permalink
    October 15, 2014 6:33 am

    “The temperature in the upper layers of these currents seems moreover to have increased by the order of 18C since the cooling during the Little Ice Age.”

    Typo?

  6. David permalink
    October 15, 2014 8:18 am

    “While the mean annual reduction of the April ice extent is decelerating by a factor of 3 between 1880 and 1980, the mean annual reduction of the August ice extent is proceeding linearly.”
    __________________

    The April v August extent data (4th chart) ends in 1998. NSIDC satellite data shows August extent 1979-98 declined at -0.4 m km^2/dec. Between 1999 and 2014 this accelerated to -1.2; around 3 times faster than 1979-98. Between 1979-98 April extent declined at -0.5; between 1999 and 2014 this slowed to -0.3.

    It’s hard to tell how post 1998 changes (assuming these were replicated in the Nordic Seas) might affect long term trends. April extent loss seems to be continuing a slow deceleration; however, would August extent loss still be described as ‘linear’ given its rapid post 1998 acceleration?

  7. Otter (ClimateOtter on Twitter) permalink
    October 15, 2014 9:10 am

    I was hoping there would be a chart on summer ice extent, July to September. Oh well.

    Reason I ask: A rabid pro-AGW type where I post my climate materials, has this piece up on Arctic ice http://scythemantis.deviantart.com/art/Arctic-Sea-ice-actual-truth-484004326

    I noticed that the chart appears to end around 2011. I managed to track the chart down to the ‘skeptical science’ blog. Their chart is slightly different, ending in 2012.

    I wrote them an email asking if they would be updating it to reflect the past two years. I finally got an answer back that they would not be updating it- but here’s a link to the NSDIC page…..

    Said page does not even contain such a chart (the closest anything gets is what david mentions just above, but, does not look like the one I linked to). So I have no idea where this actually came from, and apparently no one wants us to see how things may have changed since 2012.

    • October 15, 2014 10:17 am

      Their graph certainly looks nothing like Vinje’s August graph. For instance, he has 2000 well above the 1950’s

      • Otter (ClimateOtter on Twitter) permalink
        October 15, 2014 8:11 pm

        Hmmm! I shall take a good look at the Vinje site.

  8. Sleepalot permalink
    October 15, 2014 9:27 am

    I appologise for being OT, but given your posts on Charles and Romania, I think you’ll be interested.

    Romania issued MV Greenpeace stamps in 1997.

    http://alynlunt.com/stamps/articles/MV%20GREEN%20PEACE%20Article.pdf

  9. Ron C. permalink
    October 15, 2014 7:05 pm

    Another pertinent study is this paper that extended the satellite record back to 1972, including the earlier Nimbus results.

    30-Year satellite record reveals contrasting Arctic and Antarctic decadal sea ice variability
    Authors D. J. Cavalieri, C. L. Parkinson, K. Y. Vinnikov

    “We have extended the analysis of Arctic and Antarctic sea ice variability from two to three decades (1973–2002) by bridging the gap between the Nimbus 7 data and the earlier Nimbus 5 satellite data record. The gap was bridged and the two satellite data records matched by using the National Ice Center (NIC) digital sea ice data set [Dedrick et al., 2001]. Most of the recent satellite-based studies of sea ice variability have concentrated on the period since late 1978, when the Nimbus 7 satellite was launched.”

    From their analysis:

    “The NH anomalies show a predominant period of 5 years, similar to what was reported by Cavalieri et al. [1997] for 1978–1996. This 5-year period falls within the broad spectral peak centered at 4.2 years obtained from an analysis of sea ice extent, area, and the Length of Day (LOD) index, used as a proxy for the El Nino/Southern Oscillation (ENSO) [Gloersen, 1995]. Regional Arctic sea ice variations result from atmospheric circulation changes and in particular from ENSO and North Atlantic Oscillation (NAO) events [Deser et al., 2000; Maslanik et al., 1996; Mysak et al., 1996; Parkinson, 2000]. Patterns of Arctic surface air temperature changes and trends [Rigor et al., 2000] are consistent with regional changes in sea ice extent [Deser et al., 2000]. A dominant mode of Arctic variability is the Arctic Oscillation (AO), and its strong positive phase during the 1990s may account for much of the recent decrease in Arctic ice extent. The AO explains more than half of the surface air temperature trends over much of the Arctic [Rigor et al., 2000].”

    http://onlinelibrary.wiley.com/enhanced/doi/10.1029/2003GL018031/

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