There will be increased rainfall due to the south Asian monsoon in the future as global carbon dioxide (CO2) levels increase, a new study by Brown University in the United States has said.
The conclusions derived by the study bolster climate model predictions that rising CO2 and higher global temperatures will lead to stronger monsoons.
Researchers recovered sediment core samples from beneath the Bay of Bengal seafloor in November 2014. These samples consist of sediment and fossils. They preserve a record of monsoon activity spanning millions of years.
The study found that periodic changes in the intensity of monsoon rainfall over the past 900,000 years were associated with fluctuations in atmospheric CO2, continental ice volume and moisture import from the southern hemisphere Indian Ocean.
They found that periods of more intense monsoon winds and rainfall tended to follow peaks in atmospheric CO2 and low points in global ice volume.
“The models are telling us that in a warming world, there’s going to be more water vapour in the atmosphere,” Steven Clemens, a professor of geological sciences (research) at Brown University and lead author of the study, said.
“In general, regions that get a lot of rain now are going to get more rain in the future. In terms of the south Asians monsoons, that’s entirely consistent with what we see in this study,” Clemens said.
He added that the south Asian monsoon was arguably the single most powerful expression of Earth’s hydroclimate. Some locations got several metres of rain each summer.
The rains are vital to the region’s agriculture and economy, but can also cause flooding and crop disruption in years when they’re particularly heavy.
Because the monsoons played such a large role in the lives of nearly 1.4 billion people, understanding how climate change might affect them was critical, Clemens said.