In their recent paper on how to avoid dangerous climate change, Y. Xu and V. Ramanathan propose strategies to keep global warming within 1.5°C by 2100 (relative to 1900). One strategy was to greatly reduce emissions of short-lived climate pollutants (SLCPs), including the sooty black material called black carbon. The main sources of black carbon are forest fires, open burning of biomass such as agricultural residue, domestic heating, cooking and lighting, diesel transportation,  and coal-fueled industrial activity. 

Wildfires alone account for about a quarter of global black carbon emissions. While considered a “natural” source of BC emissions, most wildfires are caused by humans (90% in the US) so they are not inevitable.  Better regulations, monitoring, enforcement and land management could make a real difference. Of course, forests must occasionally burn for the good of their ecosystems but the process could be managed more effectively to minimize harm to the environment and climate. This is basically a matter of political will, good governance, financial resources, and less corruption.  Slow and steady, onward we march.

Diesel transportation and household burning of solid fuels together account for almost 60% of global black carbon emissions. Transitioning to cleaner, more efficient transportation and household technologies would go a long way to making a serious dent in BC emissions. Luckily, we’re making a lot of progress on both these fronts. For example, California’s air quality policies are expected to “virtually eliminate” black carbon emissions from on-road diesel engines within 10 years.  Since these policies are based on existing technologies, they could be deployed throughout the U.S. and the world. And the Global Alliance for Clean Cookstoves anticipates that by 2020 more than 100 million households will gain access to clean and/or efficient cookstoves and fuels. 

Wildfires, diesel transportation, and household burning of solid fuels are responsible for the lion's share of black carbon emissions, as in close to ninety percent. Phasing out or reducing dirty coal, agricultural burning, and oil/gas sector flaring would take care of almost all the balance. Real progress is being made in all these areas.

The big question mark is China, which is fast becoming the largest contributor to global BC emissions.

Next: Tackling methane