Cutting methane key to curb warming: UN

Cutting the super-potent greenhouse gas methane quickly and dramatically is the world's best hope to slow and limit the worst of global warming, a new United Nations report says.

If human-caused methane emissions are cut by nearly in half by 2030, a 0.3C-amount of warming can be prevented by mid-century, according to Thursday's report by the United Nations Environment Programme.

The report said the methane reduction would be relatively inexpensive and could be achieved by plugging leaks in pipelines, stopping venting of natural gas during energy drilling, capturing gas from landfills and reducing methane from belching livestock and other agricultural sources.

Because methane helps make smog, cutting annual emissions of the gas by 45 per cent or nearly 180 million metric tonnes could potentially prevent about 250,000 deaths a year worldwide from pollution-triggered health problems, the UN said.

"It is absolutely critical that we tackle methane and that we tackle it expeditiously," United Nations Environment Programme Director Inger Andersen said on Thursday.

Andersen said without both methane and carbon dioxide reductions the world cannot achieve the goals in the 2015 Paris climate agreement.

Study lead author Drew Shindell, a Duke University Earth sciences professor, said recent acceleration of methane emissions "is really taking us far far off" the Paris goals.

Princeton University climate scientist Michael Oppenheimer, who wasn't part of the report and co-wrote a study last week on the gas, called methane "the best dial we can turn to slow the rate of warming".

Methane reduction can provide short-term help in the long effort to curb global warming because it iss more potent yet shorter-lived than carbon dioxide, Shindell said.

Methane only lasts a dozen years in the air while carbon dioxide sticks around for centuries.

Per molecule, methane traps dozens of times the heat of carbon dioxide.

There is 200 times more carbon dioxide in the air than methane.

"If you think we are close to climate tipping points, methane cuts are a way to quickly reduce warming," said Breakthrough Institute climate director Zeke Hausfather.