Climate Change May Have Impacted Half of 2012’s Extreme Weather
2012 was a rough year around the globe, and not for any of the Planet X/Mayan calendar doomsday reasons people feared. Instead, it was a year of extreme weather: drought and heat waves in the United States; record rainfall in the United Kingdom; unusually heavy rains in Kenya, Somalia, Japan, and Australia; drought in Spain; floods in China. And of course there was Superstorm Sandy.
One of the first questions asked in the wake of such an extreme weather event is: “Is this due to climate change?” In recent years, a brand of research called “climate attribution science” has sprouted from this question, examining the impact of extreme events to determine how much—often in fractional terms—is related to human-induced climate change, and how much to natural variability (whether in climate patterns such as the El Niño/La Niña-Southern Oscillation, sea-surface temperatures, changes in incoming solar radiation, or a host of other possible factors).
In a report published online today in the Bulletin of the American Meteorological Society (PDF), scientists with the National Oceanic and Atmospheric Administration (NOAA) tackled this question head-on. The report—the second such annual report—analyzes the findings from about 20 scientific studies of a dozen or so extreme weather events that occurred around the world last year, seeking to parse the relative influence of anthropogenic climate change. The overall message of the report: It varies.
“About half of the events … reveal compelling evidence that human-caused change was a [contributing] factor,” said NOAA National Climatic Data Center Director Thomas Karl today at a press conference accompanying the release of the report. In addition, noted climate scientist Peter Stott of the U.K. Met Office, these studies show that in many cases, human influence on climate has increased the risks associated with extreme events.
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