Nature reports:

Methane concentrations in the atmosphere raced past 1,900 parts per billion last year, nearly triple preindustrial levels, according to data released in January by the US National Oceanic and Atmospheric Administration (NOAA). Scientists says the grim milestone underscores the importance of a pledge made at last year’s COP26 climate summit to curb emissions of methane, a greenhouse gas at least 28 times as potent as CO₂.

The growth of methane emissions slowed around the turn of the millennium, but began a rapid and mysterious uptick around 2007. The spike has caused many researchers to worry that global warming is creating a feedback mechanism that will cause ever more methane to be released, making it even harder to rein in rising temperatures.

“Methane levels are growing dangerously fast,” says Euan Nisbet, an Earth scientist at Royal Holloway, University of London, in Egham, UK. The emissions, which seem to have accelerated in the past few years, are a major threat to the world’s goal of limiting global warming to 1.5–2 °C over pre-industrial temperatures, he says. [Continue reading…]