Oceans play key role in global 'warming hiatus'

Increased heat uptake across three oceans - North Atlantic, the Southern Ocean and Equatorial Pacific Ocean - is the likely cause of the 'warming hiatus' -- the current decade-long slowdown in global surface warming, says a study involving an Indian-origin scientist.

The increased oceanic heat drawdown has played a significant role in the hiatus, the findings showed.

"The deeper understanding gained in this study of the processes and regions responsible for variations in oceanic heat drawdown and retention will improve the accuracy of future climate projections," said Bablu Sinha from National Oceanography Centre (NOC) in Britain.

The researchers used data from a range of state-of-the-art ocean and atmosphere models.

"This study attributes the increased oceanic heat drawdown in the equatorial Pacific, North Atlantic and Southern Ocean to specific, different mechanisms in each region," professor Sybren Drijfhout from University of Southampton said.

"This is important as current climate models have been unable to simulate the hiatus. Our study gives clues to where the heat is drawn down and by which processes," Drijfhout added.

Previously, the drawdown of heat by the Equatorial Pacific Ocean over the hiatus period, due to cool sea-surface temperatures associated with a succession of cool-surface La Nina episodes, was thought to be sufficient to explain the hiatus.

However, this new analysis revealed that the northern North Atlantic, the Southern Ocean and Equatorial Pacific Ocean are all important regions of ocean heat uptake.

The study appeared in the journal Geophysical Research Letters.