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One study found that the Indian Ocean had played a much larger role in driving climate change during the last ice age than expected and that it could again disrupt the tropical climate.
The study by researchers at the University of Texas at Austin in the United States could rewrite established theories centered on tropical climate change focused on the Pacific.
"The processes we have uncovered are particularly important in predicting the future impacts of climate change," said Pedro DiNezio, research associate at the University of Texas Institute of Geophysics (UTIG), who was leading the research team.
"Such climate change like this could have a huge impact on the availability of water on the highly populated coastline of the Indian Ocean," DiNezio said.
Scientists studied tropical climate changes under 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 that the tropics changed dramatically during this period, they still did not understand what was driving these climate changes.
Today, the Indian Ocean is characterized by uniformly hot and stable precipitation patterns.
The reason is that the prevailing winds blow from west to east, keeping warmer waters on the east side of the region and creating rainy conditions on countries like Thailand and Indonesia.
During the LGM, however, the tropics were hit by dramatic changes, including a reversal of prevailing winds and unusual changes in ocean temperature.
"The geological record tells us that Indonesia and the eastern monsoon regions of the Indian Ocean have become drier and cooler, while the west has become more humid and stayed warmer, "said Jessica Tierney, a paleoclimatologist at the University of Arizona in the United States.
To find the causes of these changes, scientists used a climate model to simulate the impact of various ice conditions on the climate.
They compared simulated results with paleoclimatic data (chemical signatures on our past climate stored in rocks and ocean sediments).
The climate model suggests that as ice sheets progress over Canada and Scandinavia, sea levels drop by nearly 400 feet, creating vast continental bridges extending from Thailand to # 39; Australia.
According to the model, these new landmasses reversed the prevailing winds, blowing from seawater to the west and allowing cold water to rise to the surface in the east. the Indian Ocean.
The results are important because they reveal that the Indian Ocean is capable of leading to drastic changes in the climate of the tropics and that climate models are capable of simulating this complex process.
"Now that we have reproduced the glacial climate conditions for the Indo-Pacific region, we are more confident that the same climate model can be used to predict the future of our planet," said Bette Otto-Bliesner, a modeling of climate at the National Center for Research on the Atmosphere. (NCAR).
The study also shows that the mechanisms at the origin of the LGM's climate changes could be peculiar to the Indian Ocean.
This is particularly important for predicting rainfall patterns in the tropics as current theories focus on the influence of the Pacific Ocean.
Although the study did not specifically investigate whether these climatic mechanisms will emerge with the warming of the Earth, the researchers believe that the role of the Indian Ocean should not be forgotten for the prediction of our planet in warming.
"As greenhouse gases increase, we could see a different type of reorganization," said Tierney.
"If that happens, it could really change our forecast of extreme rainfall and extreme weather in countries bordering the Indian Ocean," she said.
First publication: Dec. 13 2018 13:57 IST
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