London: India, which relies heavily on the monsoon rains for its vital agriculture sector, may suffer "frequent and severe" failures in its monsoon system due to global warming in next 200 years, a new research has warned.
The effects of this unprecedented decline in rainfall by 40-70 percent 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", according to the researchers.
India's monsoon, which lasts from June to September, is vital for the country's 1.2 billion people to grow crops such as rice, wheat and corn. The South-West monsoon accounts for more than 70 percent of rainfall in India.
Researchers at the Potsdam Institute for Climate Impact Research and Potsdam University found that as we move towards the end of the 21st, and into the 22nd, century, increasing temperatures and a change in strength of the Pacific Walker circulation in spring could cause more frequent and severe changes in monsoon rainfall, the journal 'Environmental Research Letters' reported.
The Walker circulation usually brings areas of high pressure to the western Indian Ocean but, in years when El Nino occurs, this pattern gets shifted eastward, bringing high pressure over India and suppressing the monsoon, especially in spring when the monsoon begins to develop.
The researchers' simulations showed that as temperatures increase in the future, the Walker circulation, on average, brings more high pressure over India, even though the occurrence of El Nino doesn't increase.
These failures of the monsoon system - defined in the study as a 40 to 70 percent reduction in rainfall below normal levels - were unprecedented in the researchers' observational record, which was taken from the India Meteorological Department and goes back to the 1870s.
The immediate effects of climate change on monsoon rainfall have already been observed by some researchers, however, the patterns of response in the coming decades are not uniform across different models and studies.
"Our study points to the possibility of even more severe changes to monsoon rainfall caused by climatic shifts that may take place later this century and beyond," lead author of the study, Jacob Schewe, said in a statement.
The study was published in the Institute of Physics (IOP) journal Environmental Research Letters.
PTI
First Published: Tuesday, November 06, 2012, 15:40