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Scientists Say Wild Weather Is Here to Stay

Cable news junkies, take heart: if you love wall-to-wall coverage of hurricanes, wildfires and superstorms, your future viewing schedules will be jam-packed.

Researchers at the AAAS Annual Meeting said that wild weather events like Superstorm Sandy and the severe Texas drought are the new normal in North America, as human-driven climate change has made these events more intense and more frequent.

Consider these facts:

•  In the 1950s, the number of days that set record high temperatures in the U.S. was equal to the number of days that set record low temperatures. By the 2000s, record highs were twice as likely as record low.

•  The amount of precipitation falling in the heaviest rain and snow events in the United States has increased by nearly 20% since the 1950s.

•  Since the 1970s, the Atlantic Ocean has seen substantial increases in nearly every measure of hurricane activity, from frequency to storm intensity.

This GOES-13 satellite image was captured on Oct. 31 at 1240 UTC as Sandy’s circulation was winding down over Pennsylvania. Sandy had been downgraded a remnant low pressure area. | Credit: NASA GOES Project

This GOES-13 satellite image was captured on Oct. 31 at 1240 UTC as Sandy’s circulation was winding down over Pennsylvania. Sandy had been downgraded a remnant low pressure area.Credit: NASA GOES Project “The scientific analyses are now indicating a strong link between changing trends in severe weather events and the changing climate,” said Donald Wuebbles, an atmospheric scientist from the University of Illinois. “Every weather event that happens nowadays takes place in the context of a changed background climate.”

“Globally the temperatures are higher, the sea levels are higher, and there is more water vapor in the atmosphere, which energizes storms. So nothing is entirely natural anymore,” he said. “The background atmosphere has changed and continues to change due to human activity.”

Extreme weather took political center stage earlier this week, when U.S President Barack Obama mentioned Superstorm Sandy and other severe weather events in his State of the Union speech.

However, the president was careful to note that “no single event makes a trend,” an idea echoed by the researchers at a AAAS news briefing.

“While a particular heat wave may have still have occurred in the absence of human-induced warming,” Wuebbles explained, “it would not have been as hot, or lasted this long, and such events would not occur as frequently.”

Ecologists and wildlife biologists have been steadily compiling evidence that climate change has profound effects on plants and animals, affecting where they thrive and when they breed or flower, among other events. But University of Texas at Austin biologist Camille Parmesan said some of these changes also can be driven by extreme weather events—even just a few days of extreme heat or rainfall.

Climate change interacts with other factors such as pollution and shrinking habitats to affect plant and animal populations, Parmesan acknowledged. But, she said, studies of coral reefs and other natural habitats suggest that “if we reduce these other human stresses, we actually can increase resilience and resistance in natural ecological systems.”

It remains to be seen whether humans can be similarly resilient in the face of extreme weather, the researchers said. The past holds several examples of other societies that did not fare so well under severe climate change.

Tree-ring records from the American Southwest, for example, suggest that drought during the 13th century may have driven the residents of Mesa Verde, Colorado to flee their fields and homes. “The historical record shows us a community that may have failed environmentally,” said David Stahle, a tree-ring scholar from the University of Arkansas. “We are doing the same thing now in terms of our heavy consumption of water and fossil fuels.”

Wuebbles said he has talked with farmers in the American Midwest who are already changing planting times and seed types in response to recent years of severe drought and floods. And other states are grappling with the financial implications of a future of weather extremes.

Texas State climatologist John Nielsen-Gammon has been tracking the fallout from his state’s ongoing drought, which he said was triggered more by extreme high temperatures than a lack of rainfall.

Reservoirs are at their lowest levels since the 1990s, and the state legislature will meet this spring to discuss a water plan that ensures supplies for the next 50 years. “But it costs $53 billion,” Nielsen-Gammon said, “and there’s presently no mechanism to fund it.”

“Up until this point, climate change has been largely an abstract concept because some of the United States has not seen a large increase in temperatures until just recently,” he added. “The awareness of the importance of dealing with climate change is just now becoming apparent within our state.”