Guest Post: Atmospheric surface warming stalled by strong Trade winds driving heat into Pacific ocean

By Michael Hopkin, The Conversation, who interviewed Steve Rintoul from CSIRO, Richard Allan Professor of Climate Science at University of Reading, and Mathew England a Climatologist at University of New South Wales.

The “pause” in global warming since 2001 can be explained by the discovery of unusually strong winds in the Pacific, climatologists have found.

Global surface air temperatures have more or less flatlined since the turn of the century, prompting some observers to claim that the planetary warming trend has stopped. But the new research, published in Nature Climate Change, shows how stronger winds have driven the excess heat down into the ocean.

Researchers led by Matthew England, a professor of climatology at the University of New South Wales, began by looking at the differences between the 1990s, when Earth’s surface was strongly warming, and the 2000s, after the hiatus began.

Previous research has already shown that cooler temperatures over the eastern Pacific are linked to a slowdown in worldwide warming, but researchers wanted to know why.

Warming may spike when Pacific Decadal Oscillation moves to a positive phase

We are currently in a negative phase of the Pacific Decadal Oscillation, a cycle with phases that can last between 15 to 30 years. During a negative phase waters are cooler and heat mixes into deeper levels of the north Pacific ocean. When the next phase change ocurrs to a positive PDO we are likely to see some of the stored ocean heat released spiking atmospheric temperatures.

The Pacific Decadal oscillation was only identified by scientists in the 1990s, and we only have accurate observational data for identifying it going back some 50-60 years. Nathan J Mantua and SR Hare from the University of Washington in Seattle described the operation of the Pacific Decadal Oscillation in the Journal of Oceanography in 2002 (Mantua & Hare 2002 PDF). Read more about the PDO from the Climate Impacts Group from University of Washington.