Looking at corals in the western tropical Pacific Ocean, Andrea Grottoli, earth sciences, and her former advisee, Branwen Williams, found records linking a profound shift in the depth of the division between warm surface water and colder, deeper water traceable to recent global warming.

This is the first real evidence supporting the predictions of climate modelers on the effects of global climate change on the subsurface ocean circulation.

Their report was published in the latest online edition of the journal Geophysical Research Letters

“We’re trying to find a way to understand how the warm water in the tropical Pacific has changed in the last century, but more importantly during the last several decades,” said Williams, who conducted this research while a doctoral student at Ohio State. Williams is now a postdoctoral fellow at the University of Toronto.

“The Pacific is really important since it serves as a strong driver and changes in this ocean can have a very strong impact on global climate and oceanography.”

What plagues modelers and researchers alike is the limited amount of information available about the ocean when studying climate change. To get a better picture, the researchers turned to a prolific form of soft coral, the Gorgonians, growing on a reef off the island nation of Palau.

“These corals ‘sway’ with the current underwater,” Grottoli explained, “like trees in the wind. Since they aren’t restricted to shallow and warmer surface waters like other tropical corals, they provide an opportunity to reconstruct a picture of subsurface ocean circulation in a region.”