The contentious “pause” in global warming over the past decade is largely due to unusually strong trade winds in the Pacific ocean that have buried surface heat deep underwater, new research has found.
A joint Australian and US study analysed why the rise in the Earth’s global average surface temperature has slowed since 2001, after rapidly increasing from the 1970s.
The research shows that sharply accelerating trade winds in central and eastern areas of the Pacific have driven warm surface water to the ocean’s depths, reducing the amount of heat that flows into the atmosphere.
In turn, the lowering of sea surface temperatures in the Pacific triggers further cooling in other regions.
The study, which is published in the journal Nature Climate Change, calculated the net cooling effect on global average surface temperatures as between 0.1C and 0.2C, accounting for much of the hiatus in surface warming. The study’s authors said there has been a 0.2C gap between models used to predict warming and actual observed warming since 2001.
The findings should provide fresh certainty about the reasons behind the warming hiatus, which has been claimed by critics of mainstream climate science as evidence that the models are flawed and predictions of rising temperatures have been exaggerated.
No, it doesn’t mean that the whole climate change thing is bollocks. But nor does it mean that the more adventurous catastrophists are correct either. Assume, for the sake of argument, that this finding is correct, entirely ticketty boo.
What that tells us is that the whole thing is still more complex than we understand it at present. If we’ve got this one process that cools by 0.2 oC a year then we obviously don’t know enough yet about climate sensitivity to be sure about anything.
And do recall the truth at the heart of of the whole argument. Climate sensitivity is the most important single number in the whole game. If there’s no positive feedback then a doubling of CO2 gives us a temperature rise of 1 oF (or is it oC?). Which really isn’t something to worry about. All of the higher estimates of temperature change come from the existence of positive feedbacks: or more precisely, from the balance of positive and negative feedbacks.
And, here, we’ve got people telling us that there is this huge and previously unknown negative feedback. So, we don’t know enough yet about that climate sensitivity to know what it is that we should be doing. Panicking or just mooching along as normal?