Scientists: Climate change caused Pakistan floods

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Monsoon rains have shifted 40-60 miles northwest in the past three decades

by Rob Crilly
The Scotsman, October 14 2010

(Islamabad) Man-made climate change was a major cause of devastating floods in Pakistan this year, shifting monsoon rains away from flood defences and into areas of the country incapable of dealing with the deluge, according to Pakistani scientists. More than 1,700 people died and millions lost their homes as catastrophic levels of floodwater surged south from mountains in the north-west of the country.

Researchers have pieced together some of the factors responsible, said Azmat Hayat Khan, a scientist at the Pakistan Meteorological Department, and have identified a change in the pattern of monsoon rains, which have shifted 40-60 miles northwest in the past three decades.

“The negative impact of this shift is that the floods have moved from eastern rivers – where there are four major rivers capable of absorbing these levels of rain – to western rivers, where there are fewer and they are less able to cope with this water,” he said.

Instead of localised flooding among the meandering rivers of the wide Punjabi flood plains, he said, this year the fast-moving water was able to wreak havoc in Khyber Pakhtunkwa, before heading south to Sindh province where it still sits today.

Mr Khan, who will present his evidence and recommendations for preventing a repeat of this year’s devastating floods at a conference in Islamabad next week, said there was “strong evidence” the shift was caused by global warming.

Industrial activity in Eastern Pakistan had increased surface temperatures, preventing water in the atmosphere falling as rain.

“Warming in eastern parts has moved the moisture west,” he said.

Pakistan’s worst natural disaster began with 400m-500mm of rain falling in just three days at the end of July – the amount expected in the whole of an average year. With much of the surrounding mountainsides cleared of trees, water from a vast catchment area poured into valleys, bursting riverbanks and killing most of the victims within those first few days.

It coincided with a second weather system brought from the north by an unusual change to the jet stream.