Humans are responsible for 25 to 40% more of the total share of methane emissions than previously estimated, according to a new study in Nature.
The methane problem: Methane is one of the most potent greenhouse gases: it's about 28 times more effective than carbon dioxide at trapping heat in the atmosphere and responsible for about a quarter of global warming. It’s produced naturally by animals, volcanoes, and wetlands, but it’s also a byproduct of oil and gas production. It’s this last form of methane that the study focused on.
How they worked it out: Researchers used ice core measurements from Greenland from 1750 to 2013, plus previous data from Antarctica. They melted the ice to release the small quantities of ancient air trapped inside. The cores act a bit like time capsules, allowing us to get a snapshot of the type of methane in the atmosphere at the time. They used the presence of the isotope carbon-14, present in methane from biological sources, as a proxy to see how much methane was from ancient fossil sources, where it is no longer present. A possible upside?: If more methane is created by humans, there’s an even bigger opportunity to rein in how much we release. Methane only stays in the atmosphere for only a decade (compared to 200 years for carbon dioxide). So efforts to cut methane, which mostly comes from the production and transportation of gas and oil, could pay big dividends right away.