Black Carbon: Dangers and Opportunities

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Photo: The glaciers in Peru have lost 22% of their area since 1983. Credit: Greenpeace

When we think of greenhouse gases, we often picture massive coal-fired power plants pouring millions of tons of carbon dioxide (CO2) into the atmosphere. Sure enough, CO2 emissions from highly industrialized countries are the primary cause of climate change – but CO2 isn’t the only culprit. Climate change is the combined effect of dozens of heat-trapping pollutants. After CO2, the second most powerful driver of climate change is "black carbon" (or soot), a particulate emission that usually comes from low-tech sources such as cooking appliances, old-fashioned diesel engines, and brush fires used to clear agricultural lands.

At first, black carbon behaves just like CO2 – when emitted into the atmosphere, black carbon traps solar radiation and raises temperatures. But unlike CO2, which remains in the atmosphere for hundreds of years, black carbon falls out of the air after just days or weeks. The soot can then accumulate as a blackened veneer on glaciers, ice fields, and high-altitude snowpack, substantially lowering the overall reflectivity of the earth's surface and causing even more solar energy to be trapped in the atmosphere – further raising temperatures.

Fortunately though, black carbon is much easier to reduce than greenhouse gas emissions. CO2 emissions are deeply intertwined with modern industrial practices and there's not going to be a quick solution. Black carbon is different – it's a "low hanging fruit" that can be addressed with comparatively simple policy changes and inexpensive technology upgrades that have been available for at least twenty years. Hence, black carbon is an appealing target because it is a big part of the problem and because we have the tools and know-how to fix it. For these reasons, AIDA is joining others in working to raise awareness and educate decision makers about the importance of controlling soot emissions in the Americas.

AIDA has released a fact-sheet designed to educate decision makers about the common-sense policies that can be implemented to eliminate black carbon emissions. Some recommendations are to:

1. Regulate agricultural brush-fires and other open-air combustion of biomass. Ban fires outright in urban areas and in regions close to glaciers;
2. Prohibit large ships from burning dirty fuels while idling in ports and sailing in areas near ice fields;
3. Require both old and new vehicles to comply with simple particulate emissions standards;
4. Increase development assistance and technology transfer to the Global South to encourage the adoption of soot-free technologies in poor countries;
5. Keep tabs on factories and power plants to make sure they comply with the highest standards for control of soot emissions.

The opportunity is tremendous. Eliminating black carbon emissions could potentially offset the next 10-20 years of CO2 emissions, giving the international community more time to develop a more comprehensive solution to the crisis.