Scientists have long been aware that the sea level of the Pacific Ocean is rising and that global surface temperatures are also increasing.

Now a new study has affirmed a link between the two phenomena, concluding that changes in the world’s average surface temperature can be predicted by measuring changes in sea level.

“We’re using sea level in a different way, by using the pattern of sea level changes in the Pacific to look at global surface temperatures — and this hasn’t been done before,” said lead author Cheryl Peyser, a doctoral candidate in geosciences at the University of Arizona.

The study was conducted by geoscientists from the University of Arizona and NASA’s Jet Propulsion Laboratory. Findings were published in the online journal Geophysical Research Letters.

The team used data measuring sea level rise in the Pacific Ocean to predict that the world’s average surface temperature will increase as much as 0.5 degrees Fahrenheit over that of 2014.

According to Peyser, “the prediction is looking on target so far.”

The team used measurements of sea level changes taken by NASA, the National Oceanic and Atmospheric Administration, and European satellites dating to 1993.

The scientists found that sea surface height was a more accurate reflection of stored heat than sea surface temperatures. Understanding this, they determined that when sea level in the western Pacific rises more than average, the rise in global surface temperatures slows.

When sea level drops in the western Pacific but increases in the eastern Pacific, as occurred in 2015, global surface temperatures increase due to heat stored in the ocean being released, according to co-author Jianjun Yin, a UA associate professor of geosciences.

The tropical Pacific Ocean is generally higher in the west because tradewinds blow east to west, pushing water to the western end.

However, the tilt seesaws over time, due in part to two climate cycles: the Pacific Decadal Oscillation and the El Nino/La Nina cycle.

The team’s investigations were initiated when Yin observed that from 1998 to 2012, a period referred to as the “global warming hiatus,” global surface temperature increases slowed down while sea level in the western tropical Pacific Ocean increased four times faster than normal.

Yin’s graduate student, Peyser, used climate models to show what the climate system would do in the absence of global warming and found that the changes of sea level in the western Pacific were correlated with changes in global surface temperature.

The researchers were then able to calculate the numerical relationship between the amount of tilt and global surface temperature and use satellite data to calculate the Pacific Ocean’s contribution to global surface temperature.

“What I found was that during years when the tilt was steep in the western Pacific, global average temperature was cooler,” Peyser said. “And when the seesaw is tilted more toward the eastern Pacific, it’s warmer.”

Yin emphasized that natural variability is crucial to understanding the warming hiatus.

During the hiatus, more heat was stored in the deeper layers of the western Pacific, muting warming at the surface. Because warm water expands, the stored heat contributed to the extreme sea level rise measured at the time. When the tilt started to flatten in 2014, when the climate cycle switched to an El Nino pattern, the stored heat was released, increasing surface warmth and lowering the sea level in the Pacific.