Global warming may unleash Asian monsoon fury

The over-a-month long devastating flood in Assam continued to remain grim, with nearly 100 deaths and 26.37 lakh people being affected. Nearly 10 lakh people are left distressed in Bihar.

Tokyo: As the world braces itself for the impact of climate change, significant research has revealed that global warming means more rain for Asian monsoon regions which can be devastating for countries like India in the form of more floods.

The over-a-month long devastating flood in Assam continued to remain grim, with nearly 100 deaths and 26.37 lakh people being affected. Nearly 10 lakh people are left distressed in Bihar.

Researchers from Tokyo Metropolitan University simulated 30 years of global warming to show significantly elevated levels of precipitation in the monsoon “trough,” a zone spanning northern India, the Indo-China peninsula, and the western parts of the North Pacific, with tropical disturbances such as typhoons and concentrated water vapour playing key roles.

The effects of the monsoon season in Asia can be devastating. Examples include the 2018 and 2020 floods in western Japan and the east Asian countries.

The region is home to a large population, and the monsoons are a major driver of global water cycles.

“It is now more vital than ever to have an accurate, detailed picture of how exactly the climate will change,” said the researchers.

“As home to a large proportion of the world population, detailed local predictions for the scale and nature of monsoons and tropical disturbances such as typhoons/cyclones have the potential to inform disaster mitigation strategies and key policymaking,” the researchers added.

A team led by assistant professor Hiroshi Takahashi sought to address this by using a high-resolution climate model known as NICAM (Non-hydrostatic Icosahedral Atmospheric Model) to study the detailed evolution of weather in the Asian monsoon regions.

It is well known that global warming leads to more precipitation, driven mostly by more water vapour in the atmosphere.

However, the different features of each region mean that the changes are far from uniform.

For example, the study found that it was not clear whether “monsoon westerlies” were enhanced, but it did find more cyclones in the trough, enough to account for the increased precipitation.

Concurrent with the increased precipitation, they also found distinct trends in water vapour over the monsoon region.

The team also focused on the effect of sea surface temperature.

Previous studies have often applied a global, uniform increase in temperature plus the regional variations created by the El Nino effect.

To separate their effects, they added them separately in two independent simulations, concluding that it was the former, a global increase in sea surface temperature, that contributed most strongly to the increased precipitation.

“With these region-specific findings, their work may play an important role in global disaster mitigation, infrastructure development and policy decisions,” the authors wrote in a university statement.

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