Earth’s natural cooling process offset global warming in past decade

No reason to become complacent in the fight against climate change, warn researchers

Published: Friday 27 February 2015

Photo: Rayandbee/Flickr

Natural cooling cycles in the Atlantic and the Pacific have offset global warming in the past decade, say researchers. However, this trend could reverse in the future, says a new study published in the journal Science.

The authors describe the slowdown as a “false pause”. “The biggest thing people should understand is that there is randomness in the climate system. The recent slowdown in no way invalidates the idea that continued burning of fossil fuels will increase Earth’s surface temperature and pose a substantial burden on human society,” Byron A Steinman, lead author of the study, told the Guardian.

According to the newspaper report, the research looked at two long-term climate phenomena that play a key role in global temperatures—the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. The authors excluded “external forces” on those oscillations, such as volcanoes and the burning of fossil fuels, to work out how much they varied naturally or internally. They concluded that such variability could influence temperatures over several decades in the northern hemisphere up to 0.15° Celsius, either with a warming or cooling effect; in recent decades it has been a cooling one. The authors claim that the study employed state-of-the-art climate models that have not been used previously.

But there is no reason to assume victory in the fight against climate change as the trend will reverse in the coming decades and global warming will accelerate. “It is perhaps the most worrying implication of our study, for it implies that the “false pause” may simply have been a cause for false complacency when it comes to averting dangerous climate change,” Michael E Mann, one of the co-authors, told the Guardian.

Climate scientists have welcomed the study. Ben Booth, a scientist at the Meteorology Office who was not involved in the study, says that the new work provides a more nuanced picture of the role natural cycles play in climate. “What this result shows is that on a decadal time scale, the variability in the oceans can have an important role to play in dampening warming,” he adds.

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