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India’s Vital Summer Monsoons May Decline In The Face Of Global Warming

November 6, 2012
India climatic zone map showing average onset (monsoon arrival) dates and wind directions prevalent during India's southwest summer monsoon. Credit: Wikipedia CC By-SA 3.0

Lawrence LeBlond for redOrbit.com – Your Universe Online

India´s monsoons are a godsend for the country´s vital agricultural sector, providing life for crops which more than a billion people rely on. But a grim forecast for the future may spell doom for the nation´s food production and economy, as summer rains will be more sparse over the next few hundred years due to global warming.

A new study by researchers at the Potsdam Institute for Climate Impact Research and Potsdam University, Germany said the effects of frequent and severe failures during the summer monsoon season would be nothing short of devastating.

The researchers define a monsoon failure as a drop in rainfall of between 40 and 70 percent–something that has never been observed before in 140 years of measurements taken by the India Meteorological Department.

The researchers note that such an unprecedented decline in precipitation would be “extremely detrimental to India’s economy which relies heavily on the monsoon season to bring fresh water to the farmlands, threatening food supplies in the country.”

India´s summer monsoon, which lasts from June to September, is imperative to the 1.2 billion people who rely on crops such as rice, wheat and corn which are grown in the country’s rich farmlands. The South-West summer monsoon accounts for more than 70 percent of the rainfall India receives.

Lead author Jacob Schewe, in a press release, said the study indicates a strong possibility of “severe changes to monsoon rainfall caused by climatic shifts that may take place later this century and beyond.”

Moving toward the end of this century and into the next, the researchers forecast calls for increasing temperatures and a change in strength of a Pacific Ocean pattern known as the Pacific Walker circulation, which occurs in springtime. This change could portend more frequent and severe changes in the summer monsoon patterns. The Walker circulation usually brings areas of high pressure to the western Indian Ocean, but in years with an El Nino this circulation gets shifted eastward, bringing high pressure over India and suppressing rainfall, according to the researchers.

While the immediate effects of climate change have already been observed with the summer monsoon, the patterns outlined over the coming decades are not agreed upon by a number of different models and studies.

Some climate models have forecast that global warming will more likely increase summer monsoons, rather than decrease them.

Findings of Schewe´s study are published in today´s issue of IOP Publishing´s journal Environmental Research Letters.


Source: Lawrence LeBlond for redOrbit.com - Your Universe Online