Smoke and Global Warming

(Clicking any of the underlined text in blue will take you to a reference on it.)

Sometimes even living simply and close to the land contributes to global warming. About 10% of world total energy consumption derives from burning renewable “biomass,” such as wood for cooking in millions of homes around the world. Energy from wood sounds good, but it turns out that renewable organics’ combustion products heat the atmosphere very efficiently – their smoke and soot include “black carbon” which soaks up solar energy.

One edited definition of the problem: Black carbon (BC) exists as particles in the atmosphere and is a major component of soot. BC warms the atmosphere by intercepting sunlight and absorbing its heat energy. BC is emitted from many common sources, such as cars and trucks, residential stoves, forest fires and some industrial facilities, and results from the incomplete combustion of fossil fuels, wood and other biomass. “Black” refers to the fact that BC particles absorb visible light, which leads to their warming the surrounding air. The contribution to global warming of one gram of BC over a century may be hundreds of times higher than that of one gram of CO2.

So what is the world doing about black carbon as a “short-term forcer” of climate change? Rapid measures to reduce emissions of black carbon and methane, a greenhouse gas that is 25 times more potent than carbon dioxide, would cut the rate of global warming quickly because both are leached out of the atmosphere faster that carbon dioxide. “We’re in a gridlock over carbon dioxide, and we’re losing time,” opined one atmospheric scientist. “This is one way to buy back some of that time, and the co-benefits are huge.” The United Nations Environment Programme explored the potential gains in a detailed assessment in 2011 (see go.nature.com/4wcwxf). Chaired by Drew Shindell of NASA, the assessment ranked hundreds of options for reducing black carbon and ozone pollution according to their potential to reduce warming.

Recognizing the problem for global climate is one thing, generating the political will and financial resources to do something about it is definitely another. Once again, the United States is the obvious political and financial leader. Americans have more to lose than most, and we’ve certainly contributed more than our share to global warming through consumption of fossil fuels.

Image by Bundesarchiv, Bild 183-1989-1218-003 / CC-BY-SA [CC-BY-SA-3.0-de (http://creativecommons.org/licenses/by-sa/3.0/de/deed.en)], via Wikimedia Commons