Black Carbon and Methane and HFCs — Oh My!


Even if you don’t track news from the “apocalypse beat” closely, the lexicon of climate science and policy is probably familiar: carbon footprint, carbon budget, two-degree scenario, CO2 equivalent, ocean acidification, sea-level rise. But here’s a term you may not know so well, which needs to come up a lot more often than it does now if we’re serious about taking “urgent action to combat climate change and its impacts“: short-lived climate pollutants.

No, it doesn’t exactly roll off the tongue. But whether we get control of SLCPs — mainly soot (more precisely, black carbon), methane, and hydrofluorocarbons (HFCs) emitted from sources like diesel engines, brick kilns, cookstoves, gas and oil wells, municipal landfills, air conditioners — in the near term will do a lot to determine whether we get control of global warming in the long term. Here’s why.

In climate change, the overall rise in earth’s temperature is, obviously, important. But so is the rate at which that temperature rise happens. Slowing the rate of change gives us badly needed time to work: time to develop and deploy green technologies, to devise and build more energy-efficient infrastructure, to transition to a low-carbon economy. Slowing the rate of global warming is one of the most important immediate problems for climate policy. And we probably can’t do it if we don’t act quickly on SLCP emissions.

Molecule for molecule, SLCPs are many times more efficient than CO2 at absorbing solar radiation. But their lifetime in the atmosphere is much shorter; hence their name. Generally SLCPs persist in the atmosphere for less than 15 years, compared to hundreds of years for CO2. A ton of methane released into the atmosphere will have caused 84 times more warming than a ton of CO2 after 20 years, —> Read More