UNITED NATIONS -- Devastating flooding that has swamped one-fifth of Pakistan and left millions homeless is likely the worst natural disaster to date attributable to climate change, U.N. officials and climatologists are now openly saying.
Most experts are still cautioning against tying any specific event directly to emissions of greenhouse gases. But scientists at the World Meteorological Organization (WMO) in Geneva say there's no doubt that higher Atlantic Ocean temperatures contributed to the disaster begun late last month.
Atmospheric anomalies that led to the floods are also directly related to the same weather phenomena that a caused the record heat wave in Russia and flooding and mudslides in western China, said Ghassem Asrar, director of the World Climate Research Programme and WMO. And if the forecasts by the Intergovernmental Panel on Climate Change (IPCC) are correct, then Pakistan's misery is just a sign of more to come, said Asrar.
"There's no doubt that clearly the climate change is contributing, a major contributing factor," Asrar said in an interview. "We cannot definitely use one case to kind of establish precedents, but there are a few facts that point towards climate change as having to do with this."
There's also no doubt that the Pakistan flooding will join the ranks of the worst natural disasters in recorded history.
The flooding started slowly at the end of July and gradually accelerated over the past two weeks. Disaster assessment maps show that almost the entire northern part of Pakistan and most of its central region have been hit.
During the most intense storms, about a foot of rain fell over a 36-hour period. Parts of the affected areas, in particular Khyber-Pakhtunkhwa province (formerly Northwest Frontier province) received 180 percent of the precipitation expected in a normal monsoon cycle. More rain is expected in the days ahead.
Records show that the famed Indus River is at its highest water level ever recorded in the 110 years since regular record-keeping began. Estimates put the number of displaced people at somewhere between 15 million and 20 million, and the government believes about 1,600 are confirmed dead.
6.5 million need food, drinking water and medicine
The International Organization for Migration says the greatest immediate need is in Punjab, where roughly 500,000 families pushed out by the floods are awaiting assistance. All told, agencies guess that about 6.5 million Pakistanis need shelter, food, potable water and medicine.
"This is a disaster which has affected many more people than I have ever seen," said John Holmes, head of the U.N. Office for the Coordination of Humanitarian Affairs, who also leads relief efforts in Haiti.
Zamir Akram, Pakistani ambassador to the U.N. center in Geneva, said floodwaters now cover an area roughly the size of England. Satellite surveys show about 160,000 square kilometers (62,000 square miles) is underwater, or about one-fifth of Pakistan's landmass and roughly equivalent to the areas of Austria, Belgium and Switzerland combined.
Asrar at the WMO says higher-than-average Atlantic temperatures and conditions made ripe by the La Niña cycle of lower temperatures in the central Pacific Ocean created the perfect conditions for the rains. Experts acknowledge that the scale of this disaster has been made worse by a history of deforestation and land-use changes in the affected areas, but Asrar insists that the sheer volume of precipitation absorbed by clouds and then dumped on Pakistan is chiefly to blame.
Climate scientists at WMO and elsewhere, including those with the U.S. National Oceanic and Atmospheric Administration, say this year's summer is one of the hottest ever, with high temperatures breaking records across the United States, Europe and Central Asia. Consequently, the surface of the Atlantic has also been much warmer than usual.