Carbon dioxide is the most widely cited culprit when it comes to greenhouse-gas emissions and global warming. But soot, or black carbon (the airborne residue from incompletely burned fossil or biomass fuels), is also being seen as another serious cause of airborne pollution and climate change.

Recent studies estimate that black carbon is responsible for 18 percent of the global warming, compared with 40 percent for carbon dioxide, according to this report in The New York Times. The small black particles of soot land on glaciers and ice caps, soak up sunlight, and accelerate polar-ice-cap melting. Scientists fear a rise in sea levels and fall in glacier-fed rivers crucial to agriculture will result.

Smoke from wood- and dung-fueled cooking fires in the developing world are now the primary source of black soot. In the U.S., scrubbers and filters mandated by states and the federal government capture most of the on small-particulate emissions by diesel engines and coal-fired plants. But fireplaces and older wood stoves in the U.S. still emit large amounts of particulate matter that includes soot (see diagram, right).

Solutions are at hand in both the industrialized and developing worlds. The U.S. Environmental Protection Agency runs a Wood Stove Changeout Campaign that provides up to a 15 percent rebate for the cost of a less-polluting, EPA-certified wood stove (PDF). The agency also offer instructions to modify fireplaces for cleaner burning.

Next week, hearings on the American Clean Energy and Security Act of 2009 will take place. The proposed legislation, introduced in March by Democratic representatives Henry Waxman and Edmund Markey would require that 25 percent of electricity generated for retail customers come from renewable sources by 2025 and calls for a reduction in global-warming-causing pollution by 83 percent by 2050. It also directs the EPA to use its existing authority under the Clean Air Act to further reduce emissions of black carbon domestically and direct aid to reduction efforts abroad.

In the developing world, higher-efficiency cooking stoves—many of which would be solar powered—can replace cooking fires. Last week, a Kenyan-based inventor was awarded a $75,000 prize for a solar stove (shown) that will cost only $5 but can boil water and bake food. It also promises to reduce respiratory ailments and deforestation in the developing world.—Gian Trotta | e-mail | Twitter

Essential information: See our buyer’s guide to pellet and wood stoves and discuss how your model is working in our fireplace and wood-stove forum.