Short-Lived Climate Pollutants and Woodburning

The smoke from wood burning heatstoves contains black carbon, termed a “short-lived climate pollutant” (SLCP) because it both damages human health, and contributes to a warming climate, especially in the near-term and especially in snow and ice regions. This is because black carbon absorbs heat when in the air and especially, when it lands on ice and snow, causing them to melt faster.

What are short-lived climate pollutants?

SLCPs include black carbon, methane, and tropospheric ozone. These are among the most important contributors to global warming after carbon dioxide. They only live in the atmosphere for a few days or weeks (for black carbon) to about a decade, whereas carbon dioxide remains in the atmosphere and influences the Earth’s climate for centuries. During their briefer time in the atmosphere however, SLCPs are extremely potent warming agents, far more powerful than carbon dioxide in the near term.  SLCPs are also air pollutants that are harmful to human health, agriculture, and ecosystems.

What is black carbon?

Black carbon is a major component of particle pollution, and is produced by incomplete combustion of fossil fuels (coal, oil and gas) and biomass (wood, peat dung and other biomass fuels). It is emitted from various sources including diesel cars and trucks, residential cookstoves and heat stoves,  agricultural open burning, wild fires and some industrial facilities. Its lifetime in the air varies from only a few days to a few weeks, but because of its extremely small size the particles can travel great distances.  Black carbon from woodstoves in North America for example can be transported to northern Canada and Greenland; and from northern Europe to the Arctic Ocean as far as the North Pole.

During its brief time in the atmosphere, black carbon’s warming impact is 460-1500 times stronger than carbon dioxide’s. It also changes meteorological conditions like cloud formation, regional circulation, and rainfall patterns. Black carbon is particularly potent in the Arctic and other snow covered areas however, when it drops out of the atmosphere and deposits on ice and snow.  Once there, it strongly accelerates the rapid melting of critical snow and ice.

Black carbon is also a health-damaging air pollutant. This is because these very small particles can penetrate deep into the human lung.  It is a primary component of particulate matter in air pollution, which is responsible for an estimated 4 million premature deaths around the world each year.

How is black carbon generated?

Black carbon (BC) and other fine particles are generated by burning fuel. BC consists of very small carbon particles that are released when fuel burns incompletely. When firewood is lit, it heats up and the water it contains vaporizes and escapes. As the temperature rises, the logs emit BC and flammable gases, leaving behind charcoal, which burns with a red glow. Many factors determine the amount of BC generated, including stove fuel efficiency, the type of fuel, and how the fire is started and maintained. You can reduce the amount of BC you generate from woodburning by following the Five Simple Steps for Better Burning.

What happens to the black carbon after it is emitted?

Some soot will deposit onto the walls of the stove, boiler or chimney and stay there, where it can greatly increase the risk of chimney fires if not frequently cleaned or “swept.”  The rest is released into the environment, either directly out of the combustion chamber and into your home or through a chimney and into the outdoor air. More efficient burning decreases the amount of BC emitted, and therefore decreases the above risks greatly.

What about other climate pollutants?

While black carbon is an unusually important SLCP resulting from inefficient woodburning, it also produces methane, ozone precursors and not least, the long-lived climate pollutant carbon dioxide.  “Burn right” techniques decreases emissions of all of these harmful climate pollutants.

For more about SLCP emissions, including from other sectors see the web page of the Climate and Clean Air Coalition at www.ccaccoalition.org.

What can I do to help?

Follow the Five Simple Steps for Better Burning, and spread the word to family, friends and neighbors!