It is said that events happened in past help in guiding to predict responses to future climate change. The predictions are of utmost importance for the places where extreme weather has been a trend for a long time, such as the Indian subcontinent.
Predicting summer monsoon rainfall is crucial to plan for the devastating impact it can have on the 1.7 billion people who live in the region.
The onset of India’s summer monsoon is linked to the heat differences between the warmer land and cooler ocean, which causes a shift in prevailing wind direction. Winds blow over the Indian ocean and pick up moisture, subsequently falling as rain over the subcontinent from June to September.
The monsoon season can either bring in drought and food shortages or severe flooding, depending on the amount of rainfall and in what duration.
Understanding how the monsoon responded to an abrupt climate transition in the past can therefore help scientists better understand its behaviour in the future.
As per a study, it has been identified that the Indian summer monsoon pulled heat and moisture into the northern hemisphere when Earth was entering a warmer climate around 130,000 years ago. This in turn led to the expansion of tropical wetlands to expand northwards. The habitats act as sources of methane, a greenhouse gas. This led to rise in further global warming and helped end the ice age.
The study tells that how sensitive the Indian summer monsoon has been during global transition into warming in the past and might still be.
During the warming period around 130,000 years ago, the Indian summer monsoon responded to southern hemisphere warming. While the northern hemisphere and other monsoon systems such as the East Asian summer monsoon affects the modern day China, Japan and the far east countries which remained in a glacial state.
The study shows that Indian summer monsoon pulled heat and moisture northwards, driving glacial melting in the northern hemisphere and helping tropical wetlands expand their range. The expansion of tropical wetlands resulted in release of methane gas into the atmosphere. Hence, leading to even more warming and resulted in global ice age.
Ours is an incredibly dynamic system. Even though we are confined to the tropics, the system is sensitive to climatic conditions in both the hemispheres.
Since, Indian summer monsoon has contributed to methane emissions, it had an outsized impact on the global climate. Earth’s internal climate system is naturally linked and abnormal changes at one place can have significant consequences over time somewhere else.
Image Credit: UT News
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