SACE | Southern Alliance for Clean Energy

Black Carbon, Diesel and Climate Change


Black carbon as a Climate Changing Agent

black_carbon_on_glaciers.jpgBlack carbon is a major component of fine particulate matter. It results from the incomplete combustion of fossil fuels and biomass. Black carbon absorbs visible light, which disturbs the planet’s radiation balance and leads to increased warming. It is a potent warming agent: one gram of black carbon causes anything from 100 to 2000 times more warming than one gram of carbon dioxide.

Black carbon affects the earth in a number of ways. It warms the atmosphere by intercepting and absorbing sunlight and radiating heat. It also darkens the surface of ice and snow in polar regions, causing melting. Its impact on cloud formation, location and lifetime results in cooling. On balance, many sources of black carbon are believed to be increasing temperatures and disrupting rainfall patterns. It differs from many other greenhouse gases in the length of time it remains in the atmosphere. Unlike carbon dioxide (CO2) and other gases that linger in the air for decades to centuries, black carbon is a short-lived climate forcer (SLCF) . It falls out of the atmosphere after only days to about a week. SLCFs are an important part of the climate problem, because immediate results could be realized from their removal.

Cutting emissions of CO2, while crucial for long-term climate stability, would take years to have an effect on global temperatures, while immediate reduction of black carbon could have swift climate benefits.

Black carbon contributes to the warming and melting in polar and seasonal-covered regions. Ice and snow generally reflect light, cooling the earth’s surface. However, when black carbon soot falls out of the atmosphere and coats snow and ice, the black carbon absorbs heat and causes ice to melt. This triggers a positive feedback loop because the melted ice can no longer reflect light and cool the air, causing warmer temperatures that lead to even more melting.

Reducing Diesel Emissions Can Help

  • The U.S. has one of the highest black carbon emissions per capita ratios in the world.
  • Diesel emissions account for a significant portion, over 50%, of black carbon released into the atmosphere in the U.S.
  • Retrofitting diesel engines can reduce black carbon emissions by more than 85%, preventing black carbon from entering the atmosphere or darkening snow covered surfaces
  • Removing black carbon is one of the most effective near-term strategies to slow global warming with the most immediate effects.
  • While CO2 and other greenhouse gases need to be dramatically reduced in the long term, reducing black carbon from diesel emissions NOW is an immediate approach in the fight to slow global warming.

Full implementation of black carbon reduction measures are projected to seriously benefit global health, avoiding 2.4 million premature deaths and a loss of 1-4% of the global yearly production of maize, rice, soybean, and wheat. By reducing diesel emissions we will reduce black carbon, helping to slow global warming. This is one of the simplest, most cost effective ways we can contribute to climate efforts, and it will give us immediate results.

What is SACE doing?

  • Advocating for federal action to prioritize clean up of black carbon;
  • Working to build support for clean construction policies in local and state sustainability plans;
  • Conducting educational outreach on diesel pollution, black carbon and solutions throughout the region; and organizing groups to call for black carbon reduction policies;
  • Promoting new cleaner technologies and fuels to reduce diesel emissions.

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