Methane – the other greenhouse gas
Bárbara Pinho looks at the problem of methane emissions and how scientists are trying to prevent them
In 1997, when the United Nations adopted the Kyoto Protocol, there was a joint agreement that carbon dioxide should be the dominant metric to measure global warming. The 25-year-old document mentions methane briefly and doesn’t strictly limit how much methane nations should be emitting. This wasn’t because specialists didn’t know the science behind global warming, but rather because their focus was on a different timescale than the one scientists now agree upon.
Methane doesn’t stay for long in the atmosphere. Its decade-long residence time starkly contrasts with carbon dioxide’s century-long span. And while methane concentration levels are far lower than those of carbon dioxide, it isn’t innocuous. In a 20 year timescale, it’s 80 times more powerful in warming the planet than carbon dioxide since it traps heat more efficiently. It’s thought that at least 25% of the warming we are now experiencing is caused by anthropogenic emissions of this short-lived gas.