Pacific Sea Levels Could Help Predict Changes in Global Temperature

Geoscientists from the University of Arizona have developed a new method in predicting changes in global surface temperature by looking at the amount of sea level rise in the Pacific.

The new method, described in a paper published in the journal Geophysical Research Letters, suggests that changes in the sea level in the Eastern and Western Pacific can be associated with the increase or decrease of global surface temperatures.

"We are the first to use sea level observations to quantify the global surface temperature variability," said Jianjun Yin, an associate professor of geosciences at the University of Arizona and co-author of the study, in a statement. "Using sea surface height rather than sea surface temperatures provides a more accurate reflection of the heat stored in the entire water column."

For the study, Cheryl Peyser, a doctoral candidate in geosciences at University of Arizona and first author of the study, used state-of-the-art climate models to determine what the climate system would do in the absence of global warming,

Their model showed that changes in sea level in the western Pacific correlated changes in the global surface temperatures. Using actual sea level data taken by NASA/NOAA/European satellites starting in 1993, the researchers calculated the Pacific Ocean's contribution to global surface temperature.

Their analysis revealed that when the tilt in the Pacific Ocean is steep in the Western Pacific, making the sea level in the Western Pacific rise more than the average, the rise in the global surface temperature slow down and Earth become cooler.

This correlation between the sea level in the Western Pacific and global surface temperature is evident during the phenomenon known as "global warming hiatus" that occurred from 1998 to 2012, when the Western Pacific increased four times faster than the average global sea level rise.

On the other hand, the global surface temperature is warmer when the tilt is steep in the Eastern Pacific, as it did in 2015.

The researchers believe that when sea level in the Western pacific rises, more heat was being stored in the deeper layer, resulting to the global warming hiatus. However, when the sea level in the Western Pacific drops, trapped heat was released, warming the Earth's surface.