Black carbon emerges as climate villain
Last week, a $6 solar cooker took top prize in a contest for best climate change innovation. It seems the award couldn’t have come at a better time. This week brought an increasing amount of scrutiny to the climate chaos wreaked by “black carbon.”
Black carbon, better known as soot, is produced in large quantities by the cookstoves traditionally used by the world’s poor. Some of these cookstoves burn wood, others burn dung, but all have in common that they produce thick clouds of smoke that coat nearby buildings, ravage the lungs of the people who use them — and attack glaciers thousands of miles away.
> 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 United States, it travels to the Arctic. The environmental and geopolitical implications of soot emissions are enormous. Himalayan glaciers are expected to lose 75 percent of their ice by 2020.
The idea that black carbon is a major contributor to climate change is so new that soot isn’t even mentioned in the 2007 IPCC report that declared evidence of global warming unequivocal. Although carbon dioxide is still the chief climate change culprit, soot may be responsible for about half as much warming as CO2 — an enormous amount.
Solar ovens are a cheap and emissions-free alternative to traditional cookstoves, one that promise great health and economic benefits to their users alongside the environmental dividends. But solar ovens aren’t a cure-all. For one thing, many types of food, such as flatbreads, can’t be prepared in a solar oven. So researchers are developing other types of cheap stoves that still burn fuel, but do so much more cleanly and efficiently. Ultimately, such ovens may be like any other consumer item, with different models for different needs.