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Indian Ocean Disrupts Climate

Today, the Indian Ocean has a predictable rainfall pattern. The prevailing winds blow from west to east, keeping warm waters over the eastern side of the region and bringing rains to Thailand and Indonesia.

However, according to research led by The University of Texas at Austin, it was a different story during the last ice age. The prevailing winds reversed, and the ocean temperatures changed — disrupting the climate as we know it. The findings could rewrite established Pacific-centric theories about tropical climate change, said Pedro DiNezio, a
research associate at the University of Texas Institute for Geophysics (UTIG) who led the team conducting the study.

“The processes we have uncovered are particularly important for predicting future impacts of climate change,” he said. “If such a climate shift were to happen again, the disruption to rainfall patterns would have serious implications for predicting water availability over the heavily populated Indian Ocean rim.”

The study was published Dec. 12, 2018, in Science Advances. UTIG is a unit of the University of Texas Jackson School of Geosciences. The scientists investigated changes in the climate of the tropics during the Last Glacial Maximum (LGM), a period of the ice age 21,000 years ago when ice sheets covered much of North America, Europe and Asia. During the LGM, the tropics were struck by dramatic changes, including a reversal of prevailing winds and uncharacteristic changes in ocean temperatures. To find what drove these changes, researchers used a climate model to simulate how various glacial conditions affected climate. They compared simulated outcomes with paleoclimate data, chemical signatures about our past climate stored in rocks and ocean sediments.

“Now that we have reproduced glacial climate conditions for the Indo-Pacific region, we are more confident that the same climate model can be used to predict our planet’s future,” said co-author Bette Otto-Bliesner, a climate modeler at the National Center for Atmospheric Research.