Opinion New research by German and Russian scientists indicates that summer temperatures in the Arctic actually fell for much of the later 20th century, plunging to the levels seen at the beginning of the industrial revolution.
The new results are said by their authors to indicate that solar activity exerted a powerful influence over Arctic climate until the 1990s, an assertion which will cause some irritation among academics who contend that atmospheric carbon is the main factor in climate change.
The latest analysis was done using the rings of Scots pines (Pinus sylvestris) from the Khibiny Mountains on the Kola Peninsula, situated between the Arctic Circle and the port of Murmansk. The tree rings were probed by specialist ring boffins at Institut für Botanik at the Universität Hohenheim in Stuttgart, cooperating with colleagues in Russia and at the Helmholtz-Zentrum für Umweltforschung (UFZ).
According to a statement issued by the UFZ:
What stands out in the data from the Kola Peninsula is that the highest temperatures were found in the period around 1935 and 1955, and that by 1990 the curve had fallen to the 1870 level, which corresponds to the start of the Industrial Age. Since 1990, however, temperatures have increased again ...
What is conspicuous about the new data is that the reconstructed minimum temperatures coincide exactly with times of low solar activity. The researchers therefore assume that in the past, solar activity was a significant factor contributing to summer temperature fluctuations in the Arctic.
"One thing is certain: this part of the Arctic warmed up after the end of the Little Ice Age around 250 years ago, cooled down from the middle of the last century and has been warming up again since 1990," says Dr Tatjana Böttger, UFZ paleoclimatologist.
The research will be unwelcome in the hard-green movement, as it appears to undermine the direct connection between human carbon emissions and global warming - indicating as it does that temperatures actually fell back to pre-industrial levels from 1950 to 1990, just as human carbon emissions were really getting into high gear. Furthermore, the previous warming trend up to 1950 actually began in 1840, before the industrial revolution had even begun.
Böttger and her colleagues also reference other Arctic temperature studies, all of which show a 20th-century temperature peak followed by major falls of one to two degrees - in one case with the peak occurring as late as 1990.
The paper produced by the scientists can be read here by subscribers to Arctic, Antarctic, and Alpine Research. ®