The Indian Ocean played a far greater role in driving climate change during the last ice age than previously believed, and may disrupt tropical climate again in the future, a study has found.
The study by researchers from the University of Texas at Austin in the U.S. could rewrite established Pacific-centric theories on tropical climate change.
The scientists investigated changes in the climate of the tropics during the Last Glacial Maximum (LGM), a period of the last ice age 21,000 years ago when ice sheets covered much of North America, Europe and Asia.
Although scientists know the tropics changed radically during this time, they did not understand what was driving these climate changes until now.
Today, the Indian Ocean is characterised by uniformly warm and stable rainfall patterns.
This is because the prevailing winds blow from west to east maintaining warmer waters over the eastern side of the region and bringing rainy conditions over countries like Thailand and Indonesia.
During the LGM, however, the tropics were struck by dramatic changes, including a reversal of prevailing winds and uncharacteristic changes in ocean temperatures.
“The geologic record tells us that Indonesia and the monsoon regions of the east Indian Ocean became drier and cooler while the west became wetter and remained warmer,” said Jessica Tierney, a palaeoclimatologist at the University of Arizona in the U.S.
The climate model suggests that as ice sheets advanced over Canada and Scandinavia, sea-levels lowered by as much as nearly 400 feet creating vast continental bridges stretching from Thailand to Australia.
According to the model, these new land masses reversed the prevailing winds, blowing seawater to the west and allowing cold water to cycle up to the surface in the eastern Indian Ocean.
The findings are important because they reveal that the Indian Ocean is capable of driving radical changes in the climate of the tropics and that climate models are able to simulate this complex process. PTI