Swift action to cut methane, a greenhouse gas (GHG), would rapidly reduce the rate of global warming while boosting health and food production, a UN report has found.
Methane arising from fossil fuel extraction, waste and agriculture – notably livestock and rice production – is a short-lived but potent climate pollutant that is second only to carbon dioxide in driving global warming.
But there are ways to cut methane emissions by 45 per cent this decade, which will avoid nearly 0.3 degrees of warming up to 2045, according to the report from the UN Environment Programme (UNEP) and Climate and Clean Air Coalition.
As methane also contributes to the creation of ground-level ozone, a dangerous air pollutant, nearly halving emissions will also prevent a quarter of a million premature deaths and 775,000 asthma-related hospital visits a year, it concludes.
Ozone pollution also harms plants and natural systems so reducing methane emissions would prevent global crop yield losses of 26 million tonnes a year, the report finds.
Emissions could be cut with cost-effective and readily available measures such as controlling leaks and vented gas from oil, gas and coal operations and stopping organic waste going to landfill where it produces methane.
Reducing production of methane gas in cattle and sheep through switching feed and supplements; dealing with manure in different ways and changing rice paddy agriculture could also cut emissions. More than 33 per cent of Irish emissions come from agriculture, mainly in the form of methane.
Additional measures such as adopting healthier diets, with reductions in red meat and dairy consumption if above recommended guidelines, to reduce livestock production, and reducing food waste would also curb methane, it notes.
UNEP executive director Inger Andersen said: "Fast and ambitious methane mitigation is one of the best strategies available today to deliver immediate and long-lasting multiple benefits for climate, agriculture, human and ecosystem health."
Meeting the Paris climate goals will need every climate action trick in the book. Cutting methane emissions should be on page one
Concentrations of GHG in the atmosphere are rapidly increasing, and without action will continue to rise to at least 2040, the report said.
About 35 per cent of human-caused methane emissions come from fossil fuel production – causing climate pollution before the fuels are even burned for energy – while 40 per cent comes from agriculture and 20 per cent from waste.
Prof Dave Reay, from the University of Edinburgh, said: "Seldom in the world of climate change action is there a solution so stuffed with win-wins. This blunt report makes clear that slashing emissions of methane – a powerful but short-lived greenhouse gas – will deliver large and rapid benefits for the climate, air quality, human health, agriculture and the economy too."
He said the prime target was global production and supply of oil, gas and coal. “By capturing methane from oil wells and coal mines, and plugging all those leaks, a major driver of climate change is cut down to size while simultaneously creating new green jobs and improving air quality for us all.
“Meeting the Paris climate goals will need every climate action trick in the book. Cutting methane emissions should be on page one,” he added.
Prof Grant Allen, from the University of Manchester, underlined the report did not mean cutting methane emissions alone would solve global warming.
“But it does mean that we can help to quickly slow the rate of global temperature increase and avoid some significant degree of warming in the near future. But achieving this will require global action,” he said.
Many of the recommended measures were easy to implement right away, such as better controlling unnecessary leaks of methane from the oil and gas industry, he added.
“Others may require rapid policy action and changes in how we use energy from natural gas... To be clear, this does not mean that cutting methane emissions alone can solve the warming problem; we must also continue to reduce CO2 emissions to meet Paris agreement targets and avoid dangerous warming.”
Dr Joeri Rogelj of Imperial College London said the report once again shows the only sensible way to deal with methane pollution is to keep in mind it was not only a climate pollutant, but also damaging to public health and sustainable development. "Not decreasing methane emissions while options to do so are readily available is ethically untenable," he believed.
Prof Myles Allen of Oxford University said the report's focus on warming outcomes, rather than the thoroughly misleading notion of "CO2-equivalent emissions" was welcome.
“Action on methane is urgently needed, and hampered by this outdated notion of CO2-equivalence [universally used by carbon footprint calculators, governments and the UN] which understates the warming impact of any new methane source [less than 20 years old] by a factor of four to five, while at the same time overstating the warming impact of a steady methane source by a factor of three to four.”
The report’s authors acknowledged this implicitly in their modelling, “but are evidently too tactful to highlight it in the executive summary,” he pointed out.