DATE: December 12, 2016

SNIP: Scientists say they are concerned at the rate at which methane in the atmosphere is now rising.

After a period of relative stagnation in the 2000s, the concentration of the gas has surged.

Methane (CH4) is a smaller component than carbon dioxide (CO2) but drives a more potent greenhouse effect.

Researchers warn that efforts to tackle climate change will be undermined unless CH4 is also brought under tighter control.

Quite why methane has suddenly spiked is not obvious. After barely moving between 2000 and 2006, the concentration in the atmosphere ticked upwards from 2007, and then jumped sharply in 2014 and 2015.

In those final two years, methane rose rapidly by 10 or more parts per billion (ppb) annually.

It is now just above 1,830ppb.