Solving the Mysteries of Hiatus in Global Warming

Global mean temperatures have been flat for 15 years despite the increase in heat-trapping greenhouse gases, but a new Scripps study shows cooling in the equatorial Pacific Ocean explains the discrepancy. New research by Scripps Institution of Oceanography, UC San Diego climate scientists attributes the attenuation of a worldwide temperature increase to a cooling of eastern Pacific Ocean waters, one that counteracts the warming effect of greenhouse gases. Simulated temperature trend patterns (right) created by climate modelers at Scripps Institution of Oceanography, UC San Diego, showed strong agreement to observed boreal summer temperatures (left) for 2002-2012. JJA stands for June July August. Image courtesy of Nature When the climate cycle that governs that ocean cooling reverses and begins warming again, the researchers predict that the planet-wide march toward higher temperatures will resume with vigor. The study does not consider when the reversal might happen, but it brings scientists closer to understanding how to look for signs of it. If researchers can estimate that climate cycle, they could also better estimate the end date of regional trends that are linked to ocean cooling, such as the drought in the southern United States that have caused an estimated tens of billions of dollars in agricultural damage since 2000.