May 18, 2009 | 14
Why is the southeastern U.S. getting cooler while the rest of the globe is warming? Thank the trees, say some researchers.
On sweltering summer days, trees and other plants emit volatile organic compounds, such as isoprene, which combine with manmade soot and other aerosols in the atmosphere to produce a cooling haze, says environmental scientist Allen Goldstein of the University of California, Berkeley.
Goldstein and his colleagues used satellite and ground sensor data to track air pollution. Over time, the cooling induced by the atmospheric haze has outpaced the warming due to rising carbon dioxide levels in the atmosphere, according to findings published in Proceedings of the National Academy of Sciences. "Nobody realized until now that enough of these aerosols were forming to influence cooling over an entire region," Goldstein says.
Apr 24, 2009 | 5
Catalytic converters have been an environmental success, but not an unqualified one. The tailpipe devices reduce the toxicity of auto emissions and cut down on the formation of smog, but they also output greenhouse gases such as carbon dioxide. Now a new study faults widespread adoption of catalytic converters for another environmental issue, albeit one without a clear immediate impact: osmium pollution.
Osmium is an extremely hard metal that exists in seawater and in the Earth's crust—and, crucially, in ores extracted and processed for platinum, which is commonly used in catalytic converters. (Platinum also finds use as a catalyst in fuel cells, another green technology.) Smelting those ores can produce osmium tetroxide, a toxic chemical, but that's not the real issue with osmium pollution, says lead study author Cynthia Chen, a graduate student in the department of Earth sciences at Dartmouth College. "I don't think we need to worry about it from a human health standpoint," Chen says, as osmium's concentrations, even as elevated by platinum production, are extremely small.
Dec 24, 2008
A federal court this week did an about-face, ruling (pdf) that the U.S. Environmental Protection Agency (EPA) must enforce admittedly faulty regulations restricting power plant emissions until they're replaced by new improved ones.
"We are convinced that, notwithstanding the relative flaws of [the Clean Air Interstate Rule, CAIR], allowing CAIR to remain in effect until it is replaced by a rule consistent with our opinion would at least temporarily preserve the environmental values [translation: clean air] covered by CAIR," the federal Court of Appeals in Washington, D.C., wrote in its decision (pdf) yesterday.
As written, CAIR is the Bush administration's plan to cut emissions of acid-rain-forming sulfur dioxide (SO2), smog-causing nitrogen oxides (NOx)and soot via a cap-and-trade program. Under the plan, which will now take effect on Jan. 1, SO2 emissons are set to be reduced by 70 percent and NOx emissions by 60 percent below 2003 levels by 2015.
Sep 3, 2008 | 2
You may have read some alarming stories recently about pollution making its way from China to the U.S. Should you worry?
In fact, a cloud of soot, sulfur dioxide and sand from China’s Gobi Desert does make it to cities of the western U.S., where it accounts for, by some measures, as much as 15 percent of local air pollution. Of course, air pollution that doesn't respect international boundaries is nothing new: the rain acidifying the lakes of eastern Canada comes from the U.S., for example.
But China is doing something about the problem, thanks to very real impacts on public health and even children's development, as we note in our recent in-depth report on China and the environment. Whether it's having one of only four cities worldwide to go carbon neutral, cleaning up indoor air by burning human waste, or pushing renewable energy, the Middle Kingdom has a host of efforts underway. Of course, there's still a growing love of cars to deal with as well.
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