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Thursday, August 26, 2010

Pakistan’s Climate Change Floods, Seen From Above

Pakistan’s Climate Change Floods, Seen From Above 

by Brandon KeimEmail Author

A series of satellite photographs conveys the epic scale of the floods sweeping through Pakistan, leaving millions homeless and the world aghast at an extreme weather disaster that experts consider the new normal.
Above at left is the central Pakistan city of Hyderabad on July 31, 2010. At right is the city on August 19, as floodwater swelled the Indus River. In coming days the water will reach the coast, joining tidal waters and inundating the floodplain. An estimated four million people are already homeless, and millions more at risk of disease. Agriculture is disrupted and a society thrown into disarray.

As University of Michigan atmospheric scientist Ricky Rood wrote on the Weather Underground blog, “What is happening in Pakistan cannot be described in a single word – like disaster or catastrophe. We are watching a combination of climate, weather, population, societal capacity, and geopolitics whose scope and ramifications are far beyond a “historic flood.”

The water has flowed south from northwestern Pakistan, where seasonal monsoon rains lasted for a month without stopping. Monsoons are normal, but the duration and intensity was bizarre. Climate scientists often describe such weather aberrations as fitting a pattern predicted by global warming — indeed, Indian subcontinent monsoons have been getting more extreme for a half-century — but don’t assign blame for specific events. In Pakistan, however, some scientists have no trouble placing blame.

“There’s no doubt that clearly the climate change is contributing, a major contributing factor,” World Climate Research Program director Ghassem Asrar told Climatewire.

While discussing a possible link between Pakistan’s floods and Russia’s heat wave, National Center for Atmospheric Research explained why the monsoons were so bad. The Indian Ocean’s surface waters have warmed by 2 °F since the late 1970s. That heats up the air, allowing it to hold more moisture, ultimately sending about 8% more water vapor into monsoon systems over land. That extra 8% stirs up the storms, causing them to pull in even more water.

“Global warming isn’t reponsible for the 85 percent” of the monsoon rain that is normal, said Trenberth. It’s responsible for the 15 extra percent — “and it’s that extra bit of water that causes devastation.”

Below are maps of the floods as overlaid onto the western, southern and eastern United States. After the jump are more before-and-after photographs of the flooding.

Images: (1) July 31 and August 19, Hyderabad./NASA. (2) Maps of the flood overlaid onto the western, south-central and eastern United Sates./BBC Dimensions. (3) August 5, Khairabad./NASA. (4) August 9 and 12, Khewali./NASA. (5) August 13 and August 18, Sukkur./NASA.

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