Coral reveals long-term link between Pacific winds, global climate

http://www.eurekalert.org/pub_releases/2014-12/ncfa-crl121914.php

Public Release: 22-Dec-2014
National Center for Atmospheric Research/University Corporation for Atmospheric Research

New research indicates that shifts in Pacific trade winds played a key role in twentieth century climate variation, a sign that they may again be influencing global temperatures.

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"Strong winds in the tropical Pacific are playing a role in the slowdown of warming over the past 15 years," said lead author Diane Thompson, a postdoctoral scientist at NCAR. "When the winds inevitably change to a weaker state, warming will start to accelerate again."

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By using climate models and observations, scientists are finding evidence that the heat is going into the subsurface ocean, perhaps as a result of changes in atmospheric circulation. A study earlier this year in Nature Climate Change, by an international team of climate scientists, pointed to unusually strong trade winds along the equator in the Pacific Ocean that are driving heat into the ocean while bringing cooler water to the surface. This is leaving less heat in the air, thereby temporarily offsetting warming from increasing greenhouse gases.

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Thompson stressed that the winds are just one contributor to changes in global climate. Another reason that temperatures leveled off in mid-century likely has to do with increased industrialization and emissions of particles that block sunlight and exert a cooling influence. Later in the century, increased emissions of greenhouse gases played a dominant role.

"This research shows that the influence of winds on climate is not anything new. These mechanisms have been at work earlier," Thompson said. "We believe this is a significant contribution to understanding the role of natural processes in modulating global temperature change."