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UA research shows sea levels predict global temp changes

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Tom Price and Tom Price | The Daily Wildcat Associate Professor Jianjun Yin answers questions about his research about Pacific Ocean water levels in the Gould-Simpson Building on Wednesday, Sept. 7. Yin has been at the University of Arizona for six years.

UA researchers have found a way to predict future global surface temperature using the sea level rise of the Pacific Ocean.

The observation of two notable phenomena which took place over the past two decades led Jianjun Yin, associate professor of geosciences, to wonder if there was a correlation between the two.

The first phenomenon was a global warming hiatus during which the global surface temperature slowed its rise, and the second was an increase in the sea level rise in the western tropical Pacific, which was sometimes four times faster than usual, according to Yin.

"Both the sea level rise in the Pacific Ocean and the global mean [average] surface temperature variability and change were treated as independent phenomena before," Yin said.

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Yin and his research team studied the two phenomena together and found that they were deeply interrelated. During the global warming hiatus from 1998-2012, heat was being stored in water columns in the western tropical Pacific, causing water to expand and rise, which was contributing to the slowed down warming of the entire globe.

The Pacific is tilted such that sea levels in the western region are always higher than those in the east. This tilt is caused by trade winds that blow warm water from east to west in the Pacific, and while it always remains true that sea levels in the western tropical Pacific are higher than those in the eastern tropical Pacific, the degree of the tilt between the two regions can differ — affecting global surface temperature.

That heat that had been stored in the western Pacific is currently being released as sea levels in the western Pacific decrease and sea levels in the eastern Pacific rise. This shift is caused by the irregular climate pattern known as El Niño.

After two years of pouring through data and running 38 different climate models, Yin and fourth-year UA doctoral student Cheryl Peyser, as well as UA geosciences professor Julia E. Cole and Felix W. Landerer of the NASA Jet Propulsion Laboratory have had their findings published by the American Geophysical Union.

In their paper, the team predicts that due to a strong El Niño in 2015/2016, the global surface temperature could increase by up to .28˚C, or .5˚F.

Peyser said this kind of increase could have a large impact on the globe.

“Yeah I think a 0.5˚F temperature rise in that short of time, it might not sound large, but it’s a big change," Peyser said. "So you are going to have places that are going to experience less and also have places that are going to experience more.”

Currently, Yin and Peyser are delving deeper into their research to try and find the mechanism that allows sea level rise in the Pacific Ocean to affect the global surface temperature so rapidly.


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