Earth/Environment

Water pollution: How sweet
A team of chemists in western U.S. states has identified a new marker of water that’s been tainted by human wastes: the artificial sweetener sucralose. In a paper posted online August 31 in Environmental Science & Technology,the researchers report finding sucralose in the water entering 15 of 19 drinking water treatment plants that they studied — and coming out in the finished water from 13 of 17 such plants. Sucralose was also detected in tap water samples downstream of eight of 12 plants. The pollutant’s persistent presence in water is “cause for concern,” the scientists say, arguing that long-term impacts of chronic exposure aren’t known. —Janet Raloff

Extreme winter warm snaps not ‘natural’
Dramatic warm spells during the past two winters cannot be explained by natural variability, finds a new study of Northern Hemisphere temperature data. Only when scientists at the Scripps Institution of Oceanography in La Jolla, Calif., included a global warming trend in their computer climate analyses did the warm spells make sense, they report September 2 in Geophysical Research Letters. By contrast, extreme cold snaps that happened during the same two winters fit comfortably within climate expectations based on the past 63 years. In fact, the scientists suggest, recent cold extremes might have been more dramatic it not for the warming trends superimposed on them. —Janet Raloff

Warming rises above the noise
Temperature estimates based on computer simulations and satellite observations confirm that Earth has been experiencing a continuing low-grade fever. Benjamin Santer of Lawrence Livermore National Laboratory and his colleagues analyzed data on the lower atmosphere (from the surface going up five miles) over timescales of at least a decade. The researchers found consistent warming of roughly 0.5 degrees Celsius over the past 32 years. “Completely independent of surface thermometer measurements,” Santer says, the findings rise above the noise that can be associated with relatively short-term natural climate phenomena such as El Ni±o. His team’s results were published online August 21 in Journal of Geophysical Research-Atmospheres. —Janet Raloff

Coal scrubbing’s stormy impacts
Technologies that efficiently remove sulfur- and nitrogen-oxide pollution from coal-fired power plants can alter the weather, European researchers report. Cleaning these pollutants from flue gases dramatically boosted a coal plant’s emission of ultrafine (nanometer scale) pollutant particles. Because these motes serve as good cloud-nucleation particles, the researchers’ new analyses show, regions downwind of plants using these scrubbers will experience less frequent rains — but potentially more vigorous downpours when storms do occur. Such changes could “introduce an unanticipated risk for regional climate and agricultural production,” especially in arid areas, the team concludes in a paper published online September 1 in Atmospheric Chemistry and Physics Discussions. —Janet Raloff

Dry cleaning brings toxic vapors home
Clothes treated with perchloroethylene — the most commonly used dry cleaning solvent in the United States and Europe — can emit vapors of the toxic chemical for many days. Researchers at Georgetown University in Washington, D.C., tucked snippets of silk, cotton, wool and polyester into the linings of jackets. After dry cleaning, none of the silk contained the chemical. All other fabric types did, with polyester retaining the most perchloroethylene after a single cycle.. With additional cleanings, perchloroethylene concentrations rose in susceptible fabrics, especially wool, the scientists report online August 26 in Environmental Toxicology and Chemistry. Even after seven days, wool had exhaled only half of its accumulated solvent —Janet Raloff