Swiss study: global heat waves on the rise

It certainly is comforting to remember that global warming is just a myth. Not rational, mind you, but definitely comforting. From the Washington Post via Newsday, Aug. 7:

WASHINGTON – Heat waves like those that have scorched Europe and the United States in recent weeks are becoming more frequent because of global warming, say scientists who have studied decades of weather records and computer models of past, present and future climate.

Although it is impossible to attribute any one weather event to climate change, several recent studies suggest human-generated emissions of heat-trapping gases have produced higher overall temperatures and greater weather variability, which raise the odds of longer, more intense heat waves.

Paul Della-Marta, a researcher at Switzerland’s Federal Office of Meteorology and Climatology, presented findings at a recent international conference on climate science in Gwatt, Switzerland, showing that since 1880 the duration of heat waves in Western Europe has doubled, and the number of unusually hot days in the region has nearly tripled.

In a separate 2004 study, researchers at Britain’s Hadley Centre for Climate Prediction and Research produced computer models showing greenhouse gas emissions had doubled the likelihood of events like the lethal 2003 European heat wave and that by 2040 it is likely such heat waves will take place every other year.

And researchers at the National Climatic Data Center in Asheville, N.C., reported this week that nighttime summer temperatures across the country have been unusually high for the past eight years, a record streak.

“It’s just incredible, when you look at this thing,” said Richard Heim, a research meteorologist at the center. He said only the Dust Bowl of the mid-1930s rivaled the sustained heat levels of recent summers.

Drew Shindell, an atmospheric physicist at NASA’s Goddard Institute for Space Studies who attended Della-Marta’s presentation, said the European findings are significant because they draw on long-term surface temperature records.

“The European records, being so long, make a convincing case that we’re already seeing changes” in the climate, Shindell said. “This is not like, ‘Centuries from now the ice sheets will melt.’ This is, ‘In a few decades it will be dramatically different.’ To me, that’s alarming.” Kevin Trenberth, chief of the climate analysis branch of the National Center for Atmospheric Research in Colorado, said, “There are very good reasons to believe that the current U.S. heat wave is at least partly caused by global warming.”

Trenberth pointed to a study published in March by the Journal of Geophysical Research that showed that for more than 70 percent of the land researchers had surveyed worldwide, the number of warm nights each year had increased and the number of cold nights had declined, between 1951 and 2003. The researchers, led by Hadley Centre scientist L.V. Alexander, concluded, “This implies a positive shift in the distribution of daily minimum temperature throughout the globe.”

Several researchers said it is hard to draw conclusions about the relationship between severe heat waves and climate change because they occur less often than other weather events and arise from specific weather conditions. Last week’s heat wave, said National Weather Service meteorologist Dennis Feltgen, stemmed from “a large persistent area of high pressure in the upper atmosphere” that drifted from the West to the East Coast. Konstantin Vinnikov, a senior research scientist at the University of Maryland at College Park, said he expected climate change would only have a minor effect on future scorchers.

See our last post on global climate destabilization.