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Cause of Global Warming's "Pause" Since 1998 Revealed

| 22 Jul 2014 14:55
Earth

Researchers have attributed the "pause" we've observed in global warming since 1998 to natural climate fluctuations.

While global temperature has continued to rise, as of 1998, the rate at which it is rising has been slowing, despite a continued rise in the levels of greenhouses gases. This apparent "pause" in global warming has been a matter of debate, but new research led by physics professor Shaun Lovejoy of Canada's McGill University may put this debate to rest.

In a recent paper published in the journal Geophysical Research Letters, Lovejoy presents the findings of his statistical analysis of the 15-year period after 1998 during which global temperature had been projected by scientists to be higher than actually observed. His conclusion? A natural cooling fluctuation in line with what has historically been observed masked the effects of anthropogenic global warming.

"We find many examples of these variations in pre-industrial temperature reconstructions" based on proxies such as tree rings, ice cores, and lake sediment, Lovejoy says. "Being based on climate records, this approach avoids any biases that might affect the sophisticated computer models that are commonly used for understanding global warming."

Further, the 1998-2013 cooling effect "exactly follows a slightly larger pre-pause warming event, from 1992 to 1998," so that the natural cooling during the "pause" is no more than a return to the longer term natural variability, Lovejoy concludes. "The pause thus has a convincing statistical explanation."

Before anyone claims that this lends proof that global warming itself is nothing more than the result of natural fluctuations in climate, Lovejoy's previous paper, which employed the same statistical methodology, "rejected [this hypothesis] with 99.9% confidence."

Of course, science is all about pursuing knowledge in a manner that holds up to rigor, so the best way to contest an idea is to attempt to scientifically disprove it. But until someone can prove otherwise, it seems the ultimate fate of our planet is death by heat.

Source: McGill University

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