ScienceShot: Drastic Cuts in Soot, Methane Won't Curb Long-Term Climate Change
Some scientists have proposed drastic cuts in the emissions of soot, methane, and other strong but short-lived greenhouse gases as a way to tackle global warming in the short term. But such approaches won’t lessen the long-term rate of climate change, a new study confirms. At current emission rates, methane and soot (from industrial activity as well as from vehicles, image) spewed into the atmosphere between 2010 and 2020 will increase the eventual peak in global average temperature by only a few hundredths of a degree, the analysis suggests. But emissions of carbon dioxide and other long-lived greenhouse gases during the same 10-year period will eventually boost peak warming about 10 times that amount, the researchers report online today in Nature Climate Change. The difference, the researchers explain, is due to disparities in the atmospheric lifetimes of these planet-warmers: Although methane and soot exert much stronger greenhouse gas effects than carbon dioxide does, they persist in the atmosphere, on average, only 12 years and a few weeks, respectively; CO2, on the other hand, sticks around for centuries. While trimming emissions of methane and soot can indeed delay warming in the short term, those measures—whether they’re taken almost immediately or implemented a couple of decades from now—will be largely irrelevant for the global climate if emissions of carbon dioxide continue unabated.
*Correction, 25 November, 1:30 p.m.: The headline to this story was changed to better match its text; decreases in the emissions of long-lived greenhouse gases such as carbon dioxide would indeed affect long-term climate change, whereas short-term influences such as soot and methane would not.