At the same time, days that saw downpours of 6 inches (15 centimeters) or more increased at least two-fold during the same period, "indicating a large increase in disaster potential," the study authors wrote.
Floods and Drought
Julia Slingo, director of climate research at the National Centre for Atmospheric Science at the University of Reading in England, says the study's overall findings are quite convincing.
She said the study is significant, because it shows that while mean rainfall may be stable, "there are changes in [how] the rain arrives—and that in itself has [important] implications."
Indian society has become highly attuned to long-standing monsoon patterns, Slingo said, noting that around 80 percent of the nation's 1.1 billion people depend on agriculture-related activities.
Too much or too little rain can spell disaster.
During the 2005 monsoon season, for example, a record 37 inches (94 centimeters) of rain fell on the financial capital of Mumbai (Bombay) in a single day in July.
The record rainfall flooded the city, wiped out surrounding shantytowns, and shut down the Mumbai stock exchange. More than a thousand people died in the deluge.
By contrast, monsoon rains were light in July 2002, causing widespread crop failures and water shortfalls, Slingo said. The drought cut 3 percent from India's gross domestic product that year.
"These extreme events emphasize the vulnerability of India to changes in monsoon behavior," she said, adding that predicting the global warming impact on India is a critical research priority.
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