John Lash | Policy Innovations
Could the silver bullet for climate change be black? The particulate matter called black carbon—a type of soot from burning fossil fuels, biofuels, and biomass—is now estimated to be the second most potent greenhouse warming agent after carbon dioxide. As a result, reduction of black carbon has gained momentum as one of the fastest means to significantly impact global warming.
This creates a unique opportunity to capitalize on the intersection between climate change and clean air initiatives. For years, reducing emissions from diesel engines has been one of the most important air quality challenges. Diesel emissions aggravate asthma, cause cancer and premature death, and are especially harmful to people who are vulnerable to respiratory illness, such as children and the elderly. The EPA estimates that its diesel emission programs will provide more than $150 billion in health benefits and prevent 20,000 premature deaths annually when fully implemented.
Diesel particulate matter emissions account for 30 percent of black carbon globally and 50 percent in the United States. Thus air quality programs that reduce diesel particulate matter should also be recognized as reducing climate change. Mining this intersection would double the bang for our buck, combining the health and financial benefits of clean air programs with the financial benefits of carbon abatement in a single cost.
New Awareness of Black Carbon’s Role
Previous estimates of black carbon’s warming potential have been deemed too low for a number of reasons. First, the warming effect of black carbon (which absorbs light) was assumed to be essentially offset by the cooling effect of organic and sulfate aerosols (which reflect light). But it turns out that the warming effect of black carbon multiplies by a factor of two when mixed with these other particles.