Big surprise: "Our Findings Contradict the IPCC"
Europe is heating up much faster than climate researchers expected, and now they think they know why: air made dramatically cleaner by anti-pollution programs. With less particle pollution clouding the air, more sunlight is coming through and the continent is getting warmer.
The 1970s were a hazy time: Cars ran on sulfur-rich gasoline, power plants and heavy industry burned sulfur-rich coal. Europe lay under a blanket of fumes filled with sulphate particles. Acid rain brought the particles back to earth, ravaging the continent's forests. That was then. The situation today is considerably different. Auto emissions are low in sulfur, power plants only run with smoke filters and acid rain is no longer an issue. But the success of efforts to restore Europe's air quality have had an unintended side effect that is just now coming to light. Because the atmosphere over Europe is increasingly clean, global warming is impacting the continent more quickly than other regions of the world.
The dwindling clouds of pollution are apparently the reason that Europe is heating faster than other mid-latitude regions. Since 1980, the average surface air temperature between the Bosporus and the Bay of Biscay has risen by almost an entire degree Celsius -- twice as much as expected. The reasons for this were until recently a matter of heated dispute. Greenhouse gases could explain half that increase, at best. But now climate researchers in Germany, Switzerland and the United States, using data and computer simulations, claim that the rise in temperatures has been caused most directly by a decline in sulfate aerosols in the atmosphere.
The dwindling clouds of pollution are apparently the reason that Europe is heating faster than other mid-latitude regions. Since 1980, the average surface air temperature between the Bosporus and the Bay of Biscay has risen by almost an entire degree Celsius -- twice as much as expected. The reasons for this were until recently a matter of heated dispute. Greenhouse gases could explain half that increase, at best. But now climate researchers in Germany, Switzerland and the United States, using data and computer simulations, claim that the rise in temperatures has been caused most directly by a decline in sulfate aerosols in the atmosphere.
Sulfate particles not only minimize the transfer of solar radiation directly, they also encourage the accumulation of water droplets and clouds in the atmosphere -- which in turn creates a second, indirect form of radiation repellent, because the light-colored surface of clouds reflects sunlight. This is where it gets complicated, though. In the landmark report issued last year by the Intergovernmental Panel on Climate Change (IPCC), the United Nations organization stated that questions persist about the effect that sulfate aerosols have on the atmosphere.
"Our findings contradict the IPCC," said Rolf Philipona of MeteoSwiss, Switzerland's national weather service. He and his colleague Christian Ruckstuhl, who now works as a researcher in California, analyzed data from 25 weather stations in northern Germany and eight in Switzerland.
"We found that the increase in radiation on the ground is considerably greater under a cloudless sky than a clouded one," Philipona told SPIEGEL ONLINE. The direct impact of particulate pollution is about five times greater than the indirect impact, he explained. That shows, he claims, that sulfate aerosols play "a truly important, immediate roll" in Europe's climate conditions.
"Our findings contradict the IPCC," said Rolf Philipona of MeteoSwiss, Switzerland's national weather service. He and his colleague Christian Ruckstuhl, who now works as a researcher in California, analyzed data from 25 weather stations in northern Germany and eight in Switzerland.
"We found that the increase in radiation on the ground is considerably greater under a cloudless sky than a clouded one," Philipona told SPIEGEL ONLINE. The direct impact of particulate pollution is about five times greater than the indirect impact, he explained. That shows, he claims, that sulfate aerosols play "a truly important, immediate roll" in Europe's climate conditions.