The biggest cause of global warming is all the carbon dioxide we’ve expelled into the atmosphere since the beginning of industrial times. The greenhouse gas traps heat in the atmosphere, raising temperatures on Earth. Even so, about one-quarter of the warming we’ve had so far is due to a less notorious greenhouse gas: methane, the major component of natural gas. Methane wasn’t much of a worry 20 years ago, but that’s changed since 2007, as methane emissions have accelerated, spiking in 2014 and again in 2018.
Scientists still don’t know exactly what’s going on, and they face an urgent challenge to find out. Methane is a far more potent greenhouse gas than CO2, even though it only lasts about a decade in the atmosphere, whereas CO2 persists for a couple of centuries. A continued rise in the amount of methane in the air could easily cancel out any near-term progress we make in reducing CO2 emissions. Methane is the low-hanging fruit in the effort to combat planetary warming.