Kohlua: It’s hard to believe that this is what’s melting the glaciers,” said Veerabhadran Ramanathan, one of the world’s leading climate scientists, as he weaved through a warren of mud brick huts, each containing a mud cookstove pouring soot into the atmosphere.
As women in ragged saris of a thousand hues bake bread and stew lentils in the early evening over fires fuelled by twigs and dung, children cough from the dense smoke that fills their homes. Black grime coats the undersides of thatched roofs. At dawn, a brown cloud stretches over the landscape like a diaphanous dirty blanket.
In Kohlua, in central India, with no cars and little electricity, emissions of carbon dioxide, the main heat-trapping gas linked to global warming, are near zero. But soot—also known as black carbon—from tens of thousands of villages such as this one, is emerging as a major and previously unappreciated source of global climate change.
Warming effects: A file photo of children covering their eyes against the smoke of a cooking fire in Kohlua village in central India. Soot is emerging as a major source of global climate change. Adam Ferguson / NYT
While carbon dioxide may be the No. 1 contributor to rising global temperatures, scientists say black carbon has emerged as an important No. 2, with recent studies estimating that it is responsible for 18% of the planet’s warming, compared with 40% for carbon dioxide. Decreasing black carbon emissions would be a relatively cheap way to significantly rein in global warming—especially in the short term, climate experts say. Replacing primitive cooking stoves with modern versions that emit far less soot could provide a much needed stop-gap, while nations struggle with the more difficult task of enacting programmes and developing technologies to curb carbon dioxide emissions from fossil fuels.
In fact, reducing black carbon is one of a number of relatively quick and simple climate fixes using existing technologies—often called “low hanging fruit”—that scientists say should be plucked immediately to avert the worst projected consequences of global warming. “It is clear to any person who cares about climate change that this will have a huge impact on the global environment,” said Ramanathan, a professor of climate science at the Scripps Institute of Oceanography, who is working with The Energy and Resources Institute (Teri) in New Delhi on a project to help poor families acquire new stoves.
“In terms of climate change, we’re driving fast towards a cliff, and this could buy us time,” said Ramanathan, who left India 40 years ago but returned to his native land for the project.
Better still, decreasing soot could have a rapid effect. Unlike carbon dioxide, which lingers in the atmosphere for years, soot stays there for a few weeks. Converting to low-soot cookstoves would remove the warming effects of black carbon quickly, while shutting a coal plant takes years to substantially reduce global carbon dioxide concentrations.
Like tiny heat-absorbing black sweaters, soot particles warm the air and melt the ice by absorbing the sun’s heat when they settle on glaciers. One recent study estimated that black carbon might account for as much as half of arctic warming. While the particles tend to settle over time and do not have the global reach of greenhouse gases, they do travel, scientists now realize. Soot from India has been found in the Maldive Islands and on the Tibetan plateau; from the US, it travels to the Arctic. The environmental and geopolitical implications of soot emissions are enormous. Himalayan glaciers are expected to lose 75% of their ice by 2020, according to Prof. Syed Iqbal Hasnain, a glacier specialist from Sikkim.
These glaciers are the source of most of the major rivers in Asia. The short-term result of glacial melt is severe flooding in mountain communities. The number of floods from glacial lakes already is rising sharply, Hasnain said. Once the glaciers shrink, Asia’s big rivers will run low or dry for part of the year, and desperate battles over water are certain to ensue.
Doctors have long railed against black carbon for its devastating health effects in poor countries. The combination of health and environmental benefits means that reducing soot provides a “very big bang for your buck,” said Erika Rosenthal, a senior lawyer at Earth Justice, a Washington organization. “Now it’s in everybody’s self interest to deal with things like cookstoves—not just because hundreds of thousands of women and children far away are dying prematurely.”
In March, the cookstove project, called Surya, began ”market testing” six alternative cookers in villages, in part to quantify their benefits. Already, the researchers fret that the new stoves look like scientific instruments and are fragile; one broke when a villager pushed twigs in too hard.
But if black carbon is ever to be addressed on a large scale, acceptance of the new stoves is crucial. “I’m not going to go to the villagers and say CO2 is rising, and in 50 years you might have floods,” said Ibrahim Rehman, Ramanathan’s collaborator at Teri. “I’ll tell her about the lungs and her kids, and I know it will help with climate change as well.”
©2009/THE NEW YORK TIMES