Mid 20thC Increase In Arctic Sea Ice

via NOT A LOT OF PEOPLE KNOW THAThttps://notalotofpeopleknowthat.wordpress.com

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.

ABSTRACT

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.

http://ift.tt/2mtBgzW

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;