As a result of incomplete combustion, traditional cook stoves and open fires produce black carbon particles that sully kitchen walls and pots. These particles also reach the snow-covered Himalayas, darkening the once-white, reflective peaks and enhancing heat absorption, Ramanathan and colleagues reported in the 2 August 2007 issue of Nature. Black carbon from cook stoves and other sources such as burning of diesel fuel is accelerating ice melt on the Himalayas, William Lau and colleagues at the National Aeronautics and Space Administration reported in December 2009 at a meeting of the American Geophysical Union.

Biomass cooking causes about two-thirds of black carbon emissions in South Asia, says Ramanathan. Last year he and his colleagues began the pilot phase of Project Surya, a study in India that seeks to measure reductions in atmospheric black carbon, methane, and ozone when families switch to cleaner stoves and lights. “In the Himalayas, the role of black carbon could be as high as fifty percent of the total glacial retreat we’ve seen so far,” he says.