BioEd Online

Monsoon rains in Asia are behaving ever more strangely, often with catastrophic effects, an Indian official has told climate experts at the Earth System Science Partnership (ESSP) meeting in Beijing.

The monsoons always have the capacity to cause flooding, and often do. But when the rains strike at an odd time or in the wrong place they can be devastating. A late onset of monsoon rains in the Marathwada region of Maharashtra state this year caused a mix-up that resulted in 400 drought-struck villages being wiped away by floodwaters, along with more than 700 deaths, Nagpur legislative member Devendra Fadnavis told conference-goers on 11 November.

A series of dams in that area catch monsoon rains and save the water for the remainder of the year. This June the reservoirs were filled to 80% of their capacity with rains, said Fadnavis, and many assumed that the monsoon, which historically has struck in late June, had done its job and delivered its water for the year. Despite drought conditions downstream, the water was saved for the anticipated even dryer months ahead.

But there has been a trend over the past five years for the monsoon in this area to be about a month late, said Fadnavis, who blames an unknown effect of climate change for the persistent delay. When the heaviest rains arrived in August 2006, officials were forced to let loose vast quantities of water to prevent the dams from being damaged, he says. The resulting floods caused massive destruction and death in villages downstream.

Those in charge of water distribution should be more aware of changing climate patterns, Fadnavis argued. "They must understand that this is a new ecological order. The planning should be shifted." If officials had anticipated further rain later in the summer, he added, they could have slowly let June's water out, alleviating drought and preventing future flooding.

Wrong place, wrong time

Climate researchers themselves remain unsure whether there really is a long-term trend of delay in the monsoons. "I am unconvinced," responded Congbin Fu, a meteorologist and head of a new ESSP project looking at environmental change in Monsoon Asia launched at this week's meeting. "This [delay] would be very important it needs to be verified," he added.

If there is a trend, notes Ahsan Uddin Ahmed, an atmospheric chemist who works with the Bangladesh Unnayan Parishad and is involved with the Monsoon Asia project, it cannot yet be pinned on climate change. "It's impossible to tell. You need decades of data," he says.

But such stories, he adds, are not uncommon. One pattern that is predicted by monsoon models is that future rains are likely to arrive in shorter, more intense bursts as they did in Maharashtra last year, when a record single-day rainfall of 944 millimetres on 26 July killed more than 1,000 people in Mumbai.

"There's no agreement in the models as to when the monsoons will happen, but they all say there will be sharp, high-intensity rains. And that means more floods," says Ahmed. India is also expecting more rain overall: 7-11% more rainfall is expected annually by the end of the century, boosting the occurrence of severe floods from once in 20 years to once every 8.3 years, he says.

Other studies indicate that winter monsoons seem to be abating, adds Fu, and the frequency of extreme events including both floods and droughts are expected to increase.

"Weird things are happening. Certainly monsoons are hitting in the wrong place at the wrong time, and officials aren't ready for it," says Fadnavis. "It's a major gamble with livelihood."

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