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Satellite Monitoring Of Arctic Sea Ice Pre 1979

April 16, 2015
tags: ,

By Paul Homewood 


h/t Mr Biscuits





I was pointing out yesterday why it was so inappropriate to deduce trends in Arctic sea ice, using 1979 as the start point. NSIDC, of course, do this supposedly because that is when satellite monitoring began.

Mr Biscuits, however, reminds me that the 1990 IPCC report showed the above graph, with Arctic sea ice extent back to 1972. They gave this narrative:






We can particularly note:


1) It must be recognized, though, that sea-ice is strongly influenced by surface winds and ocean currents so that the consequences of global warming for changes in sea-ice extent and thickness are unlikely to be straightforward.

2) Especially importantly, satellite observations have been used to map sea-ice extent routinely since the early 1970s.

3) Since about 1976 the areal extent of sea-ice in the Northern Hemisphere has varied about a constant climatological level but in 1972-1975 sea-ice extent was significantly less.


One other thing is worth noting, and that is the Antarctic sea ice. You may notice that this was above average in the early 1970’s, at the time when Arctic ice was below average.

We are now expected to believe that recent increases in Antarctic sea ice extent have something to do with global warming, melting glaciers or whatever. With the benefit of hindsight, we can see that this is just a load of bull, and that such increases and decreases are just part of the natural climate.

  1. mkelly permalink
    April 16, 2015 7:34 pm

    I have pointed this out here and other blogs. Steve Goddard has a page with this on it that I normally reference.

  2. April 16, 2015 8:34 pm

    At the risk of repeating myself, what about this remarkable recent narrative?

    • AndyG55 permalink
      April 16, 2015 8:56 pm

      I note that Snowy’s graphs bears little resemblance in the 1973 – 1976 period to the one NH from the IPCC.

      More data “adjustment” ???

    • April 17, 2015 9:59 am

      They did not have satellites in 1953.

      • April 17, 2015 10:52 am

        What the NSIDC actually say regarding their dataset that starts in 1978 is:

        “This product is designed to provide a consistent time series of sea ice concentrations (the fraction, or percentage, of ocean area covered by sea ice) spanning the coverage of several passive microwave instruments.”

        Note that there is no mention of “when satellite monitoring began”. See also their Nimbus Data Rescue project, which has data going back to 1964:

        “Consistent time series” are the operative words

  3. April 17, 2015 12:36 am

    Antarctica warmed during the 1950s to 1980s, and sea ice declined. Antarctica has cooled since the 1980s (even the IPCC has agreed), and sea ice has risen. Could it really be this simple? Answer: Yes.
    Another analysis of a 21-station data set from Antarctica by Comiso (1999) found a warming trend equivalent to 1.25°C per century for a 45-year record beginning in the 1950s but a slight cooling trend from 1979 to 1998. The slight cooling trend for this later 20-year period also was confirmed via analysis of surface temperatures over the whole continent, as inferred from satellite data.
    We present the first proxy record of sea-ice area (SIA) in the Ross Sea, Antarctica, from a 130 year coastal ice-core record. High-resolution deuterium excess data show prevailing stable SIA from the 1880s until the 1950s, a 2–5% reduction from the mid-1950s to the early-1990s, and a 5% increase after 1993. Additional support for this reconstruction is derived from ice-core methanesulphonic acid concentrations and whaling records. While SIA has continued to decline around much of the West Antarctic coastline since the 1950s, concurrent with increasing air and ocean temperatures, the underlying trend is masked in the Ross Sea by a switch to positive SIA anomalies since the early-1990s. This increase is associated with a strengthening of southerly winds and the enhanced northward advection of sea ice.

    Click to access fan.antarctic_seaice_trends.grl14.pdf

    This study compares the distribution of surface climate trends over the Southern Ocean in austral summer between 1979–2011 and 1950–1978, using a wide variety of data sets including uninterpolated gridded marine archives, land station data, reanalysis, and satellite products. Apart from the Antarctic Peninsula and adjacent regions, sea surface temperatures and surface air temperatures decreased during 1979–2011, consistent with the expansion of Antarctic sea ice. In contrast, the Southern Ocean and coastal Antarctica warmed during 1950–1978. Sea level pressure (SLP) and zonal wind trends provide additional evidence for a sign reversal between the two periods, with cooling (warming) accompanied by stronger (weaker) westerlies and lower (higher) SLP at polar latitudes in the early (late) period. Such physically consistent trends across a range of independently measured parameters provide robust evidence for multidecadal climate variability over the Southern Ocean and place the recent Antarctic sea ice trends into a broader context. ….. For the Southern Ocean as a whole, sea surface temperature has decreased by approximately 0.6°C in December-February (0.4°C in the annual mean) while Antarctic sea ice cover has increased by approximately 9% in December-February (12% in the annual mean) during 1979-2011.

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