Ups-and-downs of Indian monsoon rainfall likely to increase under warming

June 20, 2013

Day-to-day rainfall in India might become much more variable due to climate change—potentially putting millions of poor farmers and the country's agricultural productivity at risk.

The Indian monsoon is a complex system which is likely to change under future global warming. While it is in the very nature of weather to vary, the question is how much and whether we can deal with it. , for example, bears the risk of flooding, and . with a comprehensive set of 20 state-of-the-art now consistently show that Indian monsoon daily variability might increase, according to a study just published by scientists of the Potsdam Institute for Climate Impact Research.

"Increased variability – this rather technical term translates into potentially severe impacts on people who cannot afford additional loss," says Anders Levermann, one of the study's authors and co-chair of PIK's research domain . "The fact that all these different models agree is a clear message that adaptation measures can be built on." Even if seasonal mean precipitation would remain unchanged, impacts could be substantial, Levermann points out. "Focusing on the average is not always useful. If rainfall comes in a spell and is followed by a drought, this can be devastating even if the average is normal. This requires the right kind of adaptation measures that account for this variability – such as intelligent insurance schemes, for example."

"Limiting global warming is key, adaptation cannot replace but rather complement it"

The strongest change of 13 to 50 percent is found in a scenario in which continue to be emitted unabated. However, even if global warming would be limited to the internationally acknowledged threshold of 2 degrees Celsius of global warming, this would bear the risk of additional day-to-day variability between 8 and 24 percent above the pre-industrial level, according to the analysis. "So limiting global warming is key to reduce day-to-day monsoon variability, adaptation cannot replace but rather complement it," says Levermann.

The researchers focused on the ten models with the most realistic monsoon pattern – a conservative approach, as these ten models yield generally lower rates of change. The other ten models showed higher rates of change. "This is not about exact percentages. It is the clear trend that conveys the message," says Arathy Menon, lead-author of the study. The scientists used the latest ensemble of climate models, prepared for the 5th assessement report of the International Panel on . All of them show increased variability.

"This is a robust indicator"

Taking into account all 20 models, the spread of results reduces when the scientists looked at the rainfall changes per degree of global warming independent of the exact time path of the warming. The consistent result is that 4 to 12 percent variability change of daily monsoon rainfall in India are to be expected per degree Celsius of warming. "This is a robust indicator," says Menon.

About 80 percent of annual rainfall in India occur during the monsoon season from June through September. Factors that could perturb rainfall regularity include the higher holding capacity of moisture of the warmer air, but also more complex phenomena like cooling in the higher atmosphere which changes current pressure and thereby rainfall patterns.

Explore further: Climate change and the South Asian summer monsoon

More information: Menon, A., Levermann, A., Schewe, J. (2013): Enhanced future variability during India's rainy season. Geophysical Research Letters (online) DOI: 10.1002/grl.50583

Related Stories

Climate change and the South Asian summer monsoon

June 24, 2012

The vagaries of South Asian summer monsoon rainfall impact the lives of more than one billion people. A review in Nature Climate Change (June 24 online issue) of over 100 recent research articles concludes that with continuing ...

Recommended for you

New study sheds light on end of Snowball Earth period

August 24, 2015

The second ice age during the Cryogenian period was not followed by the sudden and chaotic melting-back of the ice as previously thought, but ended with regular advances and retreats of the ice, according to research published ...

Earth's mineralogy unique in the cosmos

August 26, 2015

New research from a team led by Carnegie's Robert Hazen predicts that Earth has more than 1,500 undiscovered minerals and that the exact mineral diversity of our planet is unique and could not be duplicated anywhere in the ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

deatopmg
1.4 / 5 (10) Jun 20, 2013
IF it ever warms at the rate predicted by the models.
deepsand
3.1 / 5 (11) Jun 21, 2013
IF it ever warms at the rate predicted by the models.

One wearies of your constant pecking at one aspect of a subject like an insane woodpecker looking for a grub in a block of concrete.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.