"Settled" science follies: Scientists "discover" massive ocean cooling around 1970; ClimateGate scientists can't agree on the cause

When the North Atlantic caught a chill : Nature News

Surface cooling could have pushed down temperatures in the Northern Hemisphere 40 years ago.
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Three-tenths of a degree may seem a small dip — but, for climate researchers, the discovery that a large patch of the ocean cooled by 0.3 °C within a few years around 1970 is a small sensation.
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The scientists had spotted the anomaly when reanalysing records of sea surface temperature. Ship-based temperature measurements can be misleading; in 2008, the same team showed that a supposed 0.3 °C drop in global mean temperatures in 1945 actually reflected a change in shipboard measurement techniques after the war2. So before concluding that the new anomaly was real, says co-author Phil Jones of the Climatic Research Unit at the University of East Anglia in Norwich, UK, "we spent a lot of time in trying to rule out possible data issues".

Thompson and his colleagues think a circulation change in the North Atlantic is a more likely culprit. But Michael Mann, a climate researcher at Pennsylvania State University in University Park, isn't so sure. He thinks that aerosols probably contributed to the global chill, and that the ocean cooling was probably the steep end of a natural climate oscillation spanning several decades. "I'm unconvinced they've shown that the model of an isolated brief event is a better fit to the data."

For Jones, the scientific debate comes as a welcome change. For the past year he has been at the centre of a controversy after allegedly compromising climate e-mails were stolen from his computer. Jones and his co-workers have been cleared of any scientific misconduct, and he says, "It's definitely good to finally talk about real science again".