Computer simulations with a comprehensive set of 20 state-of-the-art climate models now consistently show that Indian monsoon daily variability might increase.

Scientists of the Potsdam Institute for Climate Impact Research said, "ups-and-downs of Indian monsoon rainfall is likely to increase under warming."

Scientists found that a 4% to 12% variability change of daily monsoon rainfall in India is to be expected with 1 degree Celsius of warming.

There is a chance of 13% to 50% change in variability will take place if greenhouse gases continue to be emitted unabated.

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% to 24%, according to the analysis.

About 80% of annual rainfall in India occurs 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.

Extreme rainfall bears the risk of flooding and crop failure, it said. The study says increased variability translates into potentially severe impacts on people who cannot afford additional loss, said lead author Anders Levermann.

"The fact that all these different models agree is a clear message that adaptation measures can be built on," he added.

Even if seasonal mean precipitation would remain unchanged, impact could be substantial, Levermann said.

"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," he said.

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

The researchers focused on the 10 models with the most realistic monsoon pattern - a conservative approach, as these 10 models yield generally lower rates of change.

The other 10 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 assessment report of the International Panel on Climate Change. All of them show increased variability.

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.