Indian monsoon failure more frequent with warming

November 05, 2012

Global warming could cause frequent and severe failures of the Indian summer monsoon in the next two centuries, new research suggests.

The effects of these unprecedented changes would be extremely detrimental to India's economy which relies heavily on the monsoon season to bring fresh water to the farmlands.

The findings have been published today, 6 November, in IOP Publishing's journal Environmental Research Letters, by researchers at the Potsdam Institute for Climate Impact Research and Potsdam University.

They 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 Walker circulation usually brings areas of high pressure to the western Indian Ocean but, in years when El Niño 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 Niño doesn't increase.

These failures of the monsoon system - defined in the study as a 40 to 70 per cent 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.

Lead author of the study, Jacob Schewe, said: "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."
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Notes to Editors

Contact

1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Press Officer, Michael Bishop:
Tel: 0117 930 1032
E-mail: Michael.bishop@iop.org

A statistically predictive model for future monsoon failure in India

2. The published version of the paper 'A statistically predictive model for future monsoon failure in India' (Jacob Schewe and Anders Levermann 2012 Environ. Res. Lett. 7 044023) will be freely available online from Tuesday 6 November.

Environmental Research Letters

3. Environmental Research Letters is an open access journal that covers all of environmental science, providing a coherent and integrated approach including research articles, perspectives and editorials.

IOP Publishing

4. IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. IOP Publishing is central to the Institute of Physics (IOP), a not-for-profit society. Any financial surplus earned by IOP Publishing goes to support science through the activities of IOP. Beyond our traditional journals programme, we make high-value scientific information easily accessible through an ever-evolving portfolio of community websites, magazines, conference proceedings and a multitude of electronic services. Focused on making the most of new technologies, we're continually improving our electronic interfaces to make it easier for researchers to find exactly what they need, when they need it, in the format that suits them best. Go to http://ioppublishing.org/.

The Institute of Physics

5. The Institute of Physics is a leading scientific society promoting physics and bringing physicists together for the benefit of all.

It has a worldwide membership of around 40 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policymakers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications. Go to www.iop.org

IOP Publishing

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