Amid rising concern over global warming and climate change, there is growing scientific recognition that eliminating soot, or black carbon, could be a time-buying, badly needed fix. Civil and environmental engineering professor Tami Bond has studied the effects of black carbon for more than a decade. Her work includes performing emission inventories and field measurements of soot-producing cook stoves and diesel engines around the world. Bond was interviewed by News Bureau Physical Sciences Editor James E. Kloeppel.
What is black carbon and how does it affect climate?
Black carbon is a tiny particle that is produced by incomplete combustion. Some people call it “soot”, and everyone has seen it spewing from the exhaust of a poorly tuned vehicle. Like anything black, it’s very good at absorbing sunlight and turning it into heat. When it’s suspended in the atmosphere, it heats the air. If it settles onto ice, the ice melts faster. Both of these changes warm the earth. Emitting 1 gram of black carbon is like running an electric space heater in the atmosphere for a week.
It’s exciting to contemplate black carbon as a climate solution because you can make a difference right away. Shortly after we stop emitting it, it is washed out of the atmosphere, so its warming ends almost immediately. We’re noticing that Earth, especially the Arctic, seems to be warming faster than expected, so we might need to put the brakes on. We can’t ignore our long-term problem – greenhouse gases, which will stay around for decades. But we might also need to take action very quickly, and we could do that by turning off black carbon.
What are the major sources of black carbon?
The major sources that are within our reach are diesel engines – like trucks and tractors – burning wood and coal in homes, and some kinds of industry. Diesel engines are about a quarter of global emissions; residential solid fuel is another quarter. We already know how to begin cleaning up these sources without giving up their services – farmers can still keep their tractors. This cleanup would also make major improvements in public health, because these particles are bad for the lungs.
A lot of black carbon is also emitted from forest and grassland burning. We have less control over that.
What can be done to reduce black-carbon emissions?
Quite a lot. We already have the technology or solutions to reduce emissions from diesel engines, residential fuel, and industry. In this country, we’ve already demonstrated that possibility. Industry is a lot cleaner than it was 75 years ago. (Illinois did a lot of the coal research that made that possible.) New engines have gotten cleaner, too, because engine improvements and end-of-pipe controls have evolved to meet emission standards. We use electricity and gas for cooking instead of wood. Even our barbecue grills use propane. In developing countries, many governments and organizations are working to bring clean household energy to the poor by improving both fuels and stoves.
The biggest challenge is figuring out good policy mechanisms and fair ways to bring that technology where it’s needed, and to do it quickly. Much black carbon comes from small engines and cookers. The people and companies who own them may not be able to afford clean cooking fuels or particle traps. Cleaning up black carbon emissions will benefit both climate and public health – it will be good for everyone. If we can reduce these emissions without hurting the emitters, we’ll make a big step on the road to sustainable development.
