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Mid 20thC Increase In Arctic Sea Ice

February 24, 2017

By Paul Homewood




A new study has found that Arctic sea ice increased as much between 1950 and 1975, as it has decreased since.

Since this conflicts with their unshakeable belief that GHGs are causing the Arctic to warm, they have had to concoct the nonsensical theory that the earlier increase was caused by aerosols.




Updated observational datasets without climatological infilling show that there was an increase in sea ice concentration in the Eastern Arctic between 1950 and 1975, contrary to earlier climatology in-filled observational datasets that show weak inter-annual variations during that time period. We here present climate model simulations showing that this observed sea ice concentration increase was primarily a consequence of cooling induced by increasing anthropogenic aerosols and natural forcing. Indeed, sulphur dioxide emissions, which lead to the formation of sulphate aerosols, peaked around 1980 causing a sharp increase in the burden of sulphate between the 1950s and 1970s; but since 1980, the burden has dropped. Our climate model simulations show that the cooling contribution of aerosols offset the warming effect of increasing greenhouse gases over the mid-twentieth century resulting in the expansion of the Arctic sea ice cover. These results challenge the perception that Arctic sea ice extent was unperturbed by human influence until the 1970s, suggesting instead that it exhibited earlier forced multi-decadal variations, with implications for our understanding of impacts and adaptation in human and natural Arctic systems.


This is the key graph. The authors’ work is based around sea ice concentration, but they are clear that this is a fair proxy for extent.

They also state that this increase is also consistent with a well documented Arctic cooling between the 1940s and the 1970s.




As has already been extremely well established, there was a significant rise in Arctic temperatures, with a corresponding reduction in sea ice, between the 1920s and 1940s.


There is no need for the contortions performed by the authors, in order to keep CO2 in the equation.

The answer to all of the changes in the Arctic during the last century lies in the Atlantic Multidecadal Oscillation, or AMO;




The AMO is a naturally occurring cycle, whereby Atlantic sea surface temperatures shift through warm and cold phases.

We are currently in the warm phase, just as we were between the 1920s and 40s, when temperatures all around the Arctic were at similar levels to now.

In between, temperatures in the Arctic fell, with a corresponding increase in sea ice.

I hope I am still around to see the egg on their faces when the AMO turns cold again.

  1. Mike Jackson permalink
    February 24, 2017 7:51 pm

    And the Wood for Trees graph shows a trend line for the period from c1850 of pre-cise-ly ZERO!

    How desperate can they get?

    • bea permalink
      February 25, 2017 9:41 am

      “How desperate can they get?”

      You ain’t seen nothing yet.

      However, it is only the chanting of the believers, working their prayer beads like mad.

      I doubt the voters for Brexit and for Trump, or the permanently unemployed of the EU, are impressed at all by news items about trends in ice-skims in far-away places.

  2. Broadlands permalink
    February 24, 2017 8:26 pm

    The Calendar year NAO index went from minus 1.16 in 1968 to plus 0.78 in 1972. A net increase of plus 1.94 in four years. Between 1950 and 1975 there were 16 volcanic eruptions with a Volcanic Explosivity Index, VEI of 4 or more…including Mt. Agung. +5

    Natural variation?

  3. February 24, 2017 8:28 pm

    Reblogged this on WeatherAction News and commented:
    But hang on NASA GISS have the mid 20thC essentially flat 😉

  4. February 25, 2017 12:05 am

    Looks like this study was out looking to find some way to blame that cycle of increasing sea ice extent on humans:

    Our climate model simulations show that the cooling contribution of aerosols offset the warming effect of increasing greenhouse gases over the mid-twentieth century resulting in the expansion of the Arctic sea ice cover.

    What warming effect of AGHS was there between 1950 and the 1970’s? Any significant rise of CO2 was just beginning during this period of time.

  5. Tom Dowter permalink
    February 25, 2017 12:38 am

    When it comes to sea ice, the warmists love to focus their attention on the Northern hemisphere. Sea ice in the Southern hemisphere represents a much greater challenge for them.

    How do they explain (away) the fact that sea ice here has been on an upward trend since proper measurements became available in 1979?

    In complete contrast, the trend since 1979 in the Northern hemisphere has definitely been downwards. To be sure, there are some years where it has been higher than in the previous year, but this does not affect the longer term trend.

    There is little doubt that global temperatures from about 1940 to about 1972 were on a downward trend. A corresponding increase in sea ice would therefore be not unexpected.

    It is worth remarking that the paper refers to MODELS. These do not have a great track record in accounting for measured global temperatures – and an even worse one where more regional predictions are concerned.

  6. February 25, 2017 12:43 am

    Also this

  7. February 25, 2017 5:01 am

    2020? When the sustained cooling sets in?

  8. Tom Dowter permalink
    February 25, 2017 7:21 am

    Although these are probably not the models used in the cited paper, it is worth seeing what the 301 CMIP5 model runs have to say about the cooling in the middle of the 20th century, (from 1940 to either 1970 or 1972).

    It would appear that they are pinning the cause of this onto the eruption of Mount Agung in 1963 and 1964.

    If we compare the apparent trend between 1940 and 1962 with that between 1940 and 1963, we find that 247, (82%), of the models show less warming in the longer period. Move on to 1964 and the figure rises to 280, (93%).

    In fact only one third of the models show any cooling prior to the Agung eruptions whereas 59% of them show a cooling once the eruptions have taken place.

    Needless to say, all three surface temperature series show a pronounced cooling prior to the Agung eruption.

    Blaming volcanoes for the cooling may be partly true – but it is certainly not the whole truth!

  9. February 25, 2017 9:43 am

    Welcome to another climatic game of ‘hide the decline’.

    • bea permalink
      February 25, 2017 10:21 am

      It is all rather reminiscent of Marxist Historians and the days of Kremlin watching.
      The future is fixed but the past keeps changing!

  10. Dick Mandemaker permalink
    February 25, 2017 10:17 am

    Hi Paul, What can you say about this message, it is widely spread via twitter and other media.

    Thanks, Dick

    Sent from Mail for Windows 10

    • bea permalink
      February 25, 2017 11:18 am

      To be blunt but accurate, it is nothing but mental mutual masturbation.

  11. Dick Mandemaker permalink
    February 28, 2017 7:29 am

    Thanks for your post!

    Sent from my Windows 10 phone

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