Nature’s Secrets

Can science cook up a solution to soot?

CORRESPONDENTMarch 17, 2013 

 

“Breathing the sooty plume from a maladjusted diesel engine or a smoldering cooking fire has always been ill-advised. But a new study finds that soot is warming the climate about twice as fast as scientists had estimated.”

Richard Kerr

Science magazine, Jan. 25

For a typical mom in rural India, breakfast does not involve take-away Starbucks, micro-waved oatmeal, frozen waffles or sparkling tableware extracted from an automatic dishwasher. Instead, it usually consists of leaning over a wood-burning stove for many hours, inhaling particulates while cooking for her family. This scenario exists for millions of moms in India, China, South America, Indonesia and Africa. While traditional cooking has a fairly small energy footprint compared to Western cooking, it also emits black carbon – otherwise known as soot.

Soot results from the incomplete combustion of fossil fuels or biomass. Common sources of soot are wildfires, diesel engines, wood stoves and agricultural burn-off.

When soot plumes settle on surfaces, the dark particles absorb heat and accelerate warming. The good news is that soot disintegrates from the atmosphere after only a few days or weeks; the bad news is that soot is on the increase.

Soot’s dark particles absorb sunlight, shrink cloud droplets and darken ice and snow (leading to accelerated melting). Scientific evidence indicates that black carbon may have caused up to 50 percent of the recent Arctic ice melt. In addition, soot causes lung disease in women and children who use wood-burning stoves.

The eradication of soot could slow down the planet’s current warming trends. A recent study published in the Journal of Geophysical Research claims that soot is warming our planet twice as fast as scientists had predicted. But all soot is not equal. According to the JGR study, reducing soot from diesel engines and from coal currently burned under less optimal conditions are top priorities.

A distant third is to reduce soot plumes from cook stoves, but this scenario also poses enormous ethical issues. Should villagers in developing countries who use very little energy during their entire lifetimes be forced to give up their cooking practices to stabilize global temperatures?

What about offering a $1 million prize for designing a clean cookstove? It must be not only durable, but also produce food that tastes good to the users to guarantee acceptance. Solar-powered stoves reduce soot by as much as 90 percent, but replacing hundreds of millions of cookstoves in developing countries is no easy task. On the other hand, some energy experts believe that changing the cookstoves of 3 billion people may actually be easier than altering the energy culture of 300 million Americans.

Meg Lowman, an N.C. State University professor and forest canopy expert, directs the N.C. Museum of Natural Sciences’ Nature Research Center. Online: www.canopymeg.com.

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