New paper on Arctic warming from PNAS -
"But then how to explain a similar rapid warming that occurred during the early 20th century, when the effects of greenhouse gases were considerably weaker than today? And what can we prove about the period, given the scarcity of usable data and observations prior to the 1950s?
Now scientists from Kyoto University and UC San Diego have discovered that this phenomenon occurred when the warming phase -- 'interdecadal variability mode' -- of both the Pacific and Atlantic Oceans coincided. The team's findings appeared recently in the journal PNAS.
"We found that early 20th century sea surface temperatures in the tropical Pacific and North Atlantic had warmed much more than previously thought," explains lead author Hiroki Tokinaga of Kyoto.
"Using observations and model simulations, we've demonstrated that rising Pacific-Atlantic temperatures were the major driver of rapid Arctic warming in the early 20th century."
Previous explanations for early Arctic warming have including decreased volcanic aerosols and increased solar radiation, but none of these have been able to simulate observed conditions from the period.
Tokinaga's team found that when the interdecadal rise in sea surface temperatures was included in simulation calculations, the results properly reflected early Arctic conditions."
https://www.eurekalert.org/pub_releases/2017-05/ku-poa052917.phpOnly models but it is the best they can do trying to interpret the past.
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