Many people think of climate change and air pollution as two different issues, stated Veerabhardan Ramanathan of the University of California, San Diego, but many pollutants have both warming effects and negative health impacts. Black carbon—a form of fine particulates emitted by diesel engines, agricultural & forest burning, cook stoves, and some industries—contributes to lung and heart disease and has significant impacts on climate by warming the atmosphere, affecting clouds and rainfall, and increasing the rate of snow melt in regions such as the Arctic and Himalayas. Black carbon can be seen as a poster child for double-hitting pollutants. Controlling sources of black carbon can provide important and potentially cost-effective opportunities to simultaneously pursue public health and climate co-benefits. At this March 17th China Environment Forum meeting, three speakers dove into the science and politics behind black carbon issues in China.
Black Carbon: A Good Place to Start
All three speakers, Veerabhardan Ramanathan, John Guy of the U.S. EPA, and Dennis Clare of the Institute for Governance & Sustainable Development emphasized that reducing black carbon should be a priority due to its high health and climate consequences and potential ease of remediation. In fact, eliminating one ton of black carbon emissions is equivalent to removing 2000 tons of atmospheric CO2. Black carbon's warming effects are increased exponentially when it is emitted near snow and ice; it not only maintains its normal radiative forcing but also reduces the albedo effect of snow. Due to these two influences, it is estimated that 50 percent of Arctic ice melt is caused by black carbon. In addition to reducing global warming and ice melt, reducing black carbon will prolong the lives of hundreds of thousands of people each year and significantly reduce incidences of lung cancer and respiratory disease.
Local Sources, International Destinations
It is not in industrialized countries but rather places like China and India that black carbon reduction promises the greatest climate and health benefits. And due to global air currents, local sources of black carbon do not stay local; their effects are felt internationally. For example, Dr. Ramanathan estimated that 75 to 80 percent of black carbon in the U.S. originates in China. This means that although China may be the number-one emitter, reduction of overall black carbon emissions remains a global issue.
Solutions in the Fuel Sector
John Guy of the U.S. EPA has been working closely with China for about 10 years on black carbon reduction efforts and has focused in three main areas: Beijing, Shanghai, and the Pearl River Delta. Most of EPA's work has dealt with reducing black carbon from heavy fuel usage e.g. diesel and marine fuels which the EPA has been working with China to reduce sulfur content of the fuel to a level at which black carbon filters can be applied. One of EPA's first projects was a demonstration on retrofitting busses. The project started with 20 busses and EPA funding and Beijing took the lessons learned from this demonstration and now there are about 9000 busses with retrofits. China is now revising their national air pollution law to incorporate new standards for sulfate and NOX which, once set, will allow the addition of black carbon filters to existing busses.
Reducing Black Carbon from Cookstoves
Dennis Clare of the Institute for Governance & Sustainable Development spoke last and touched on the issue of cookstoves in rural areas. There are currently 150 million homes using biomass cookstoves in China and these stoves account for a greater source of black carbon than emissions from the transportation sector. In addition, black carbon from cookstoves is a significant source of respiratory disease in rural areas. This combined with the fact that many cookstoves are located in rural areas near glaciers and that solutions are relatively cheap and available, make cookstove replacements a promising area for black carbon reductions. Mr. Clare emphasized that reducing black carbon emissions from cookstoves may be the most cost effective method as newer stoves are readily available and are relatively cheap.
Out of the Black, Into the Blue
On-the-shelf technologies and practices are currently available to significantly reduce black carbon emissions, from cook stoves to diesel trucks and industrial processes. Great strides have been taken in the last 20 years to reduce black carbon emissions in industrialized countries. If these technologies and practices can be applied to developing countries and improved in industrialized countries, the global health and climate outlook would be significantly improved. The three speakers concluded each of their presentations with the point that because black carbon emissions have both high climate and health consequences and readily available methods to reduce those emissions, the focus and efforts to reduce black carbon can and should be increased.