Fresh analysis of existing data suggests that increased greenhouse gas emissions have played a role in the weakening of a major atmospheric circulation system over the tropical Indo-Pacific Ocean over the past half-century, according to a new study by researchers at the University of Miami.

The findings offer new evidence that climate change will affect rainfall patterns in the area and amplify warming near the equator.

The researchers used historical observations of cloud cover as a substitute for wind velocity in climate models to analyze the so-called Walker circulation.

The Walker circulation is a pattern of atmospheric air flow and heat distribution in the tropic Pacific region that affects patterns of tropical rainfall.

Based on the new analysis, there was a weakening and eastward shift of the Walker circulation over the past century due to greenhouse gas emissions.

“This study makes innovative use of a decades-old data set,” said Amy Clement, a  professor of atmospheric science at the Rosenstiel School of Marine & Atmospheric Science. “It is impressive that visual observations from the decks of ships transiting the Pacific Ocean over a half-century can tell us something so fundamental about climate change.”

The study further suggests rainfall could decrease over Indonesia and the western Pacific and increase over the central Pacific Ocean.

The study, “Evidence for Weakening of the Walker Circulation from Cloud Observations,” was published last month in the journal Geophysical Research Letters.