There is no substitute for eliminating fossil fuels and stopping the release of carbon dioxide into the atmosphere to avoid the painful and disruptive effects of global warming. The latest report from the Intergovernmental Panel on Climate Change (IPCC) leaves no doubt about this. But CO2 is not the only greenhouse gas. The climate panel also highlights the problem – and the opportunity – posed by methane, which has contributed up to 0.5 ° C to warming since pre-industrial times, just behind CO.2.
Methane is the main component of natural gas, whose popularity as a relatively clean fossil fuel source has grown by more than 50% over the past two decades. In the United States, the supply of cheap and plentiful natural gas – obtained from controversial hydraulic fracturing – has helped displace coal. But there has also been a cost to the climate: Fossil fuels have helped increase methane concentrations in the atmosphere, which have more than doubled since pre-industrial times, from around 700 parts per billion by volume to nearly 1,900 ppb in 2020.
Methane is worrying because it has a disproportionate impact on the climate. Gas represents a tiny fraction of our atmosphere – CO2 the levels are over 200 times higher. But in the first 20 years after its release, methane is about 80 times more potent than CO.2 to trap heat in the earth’s atmosphere. It also breaks down much faster than CO2, with an average lifespan of the order of a decade, compared to centuries for CO2. This means that reducing methane emissions could provide short-term relief as governments and businesses negotiate the more difficult transition from fossil fuels to clean energy.
In an effort to reduce methane emissions, scientists have studied two related questions. First, what are the main sources of methane? Second, where are the worst offenders? Livestock is the biggest source, responsible for 31% of the global total, according to Ilissa Ocko of the nonprofit Environmental Defense Fund (EDF) in New York and her colleagues.1. Oil and gas operations come second, freeing up 26%. Other sources include landfills, coal mines, rice paddies and water treatment plants.
Reducing methane from livestock presents a particular challenge. People could eat less meat, but persuading people to change their diet is rarely easy. In addition, meat consumption is increasing in low- and middle-income countries, along with rising incomes. It should be easier to reduce emissions from other sectors. In many cases, it would cost nothing – and it could even be profitable.
Global methane emissions could be reduced by 57% by 2030 using existing technologies, report Ocko and colleagues. And nearly a quarter of the world’s total methane could be phased out at no net cost. The oil and gas industry could make the biggest difference here, having both the infrastructure and the incentive to minimize methane loss: more methane in their pipelines means more revenue. In other sectors, operators of landfills, coal mines and sewage treatment plants could capture the gas and use it to generate electricity. And rice farmers could minimize emissions through better irrigation and soil management practices. If these measures were implemented worldwide, predicted increases in global warming could be reduced by 0.25 ° C by 2050 and 0.5 ° C by 2100, according to the study. These are significant numbers given that the world has already warmed by 1.1 ° C and world leaders have pledged to limit the total to 1.5-2 ° C.
The main problem is to determine precisely where the methane emissions are coming from. More than a decade ago, researchers monitored methane from aircraft studies using infrared sensors capable of detecting gases in sunlight reflected from the Earth.2. Today, satellites are part of this surveillance effort. Research shows that a relatively small number of “super-emitters” are responsible for a significant portion of methane emissions, especially in the oil and gas industry.3.
The ability to identify the main sources of methane is expected to increase over the next two years. In 2022, EDF will launch a satellite designed to identify emissions over large areas of land. Carbon Mapper, a nonprofit partnership that includes NASA’s Jet Propulsion Laboratory and San Francisco-based company Planet, will follow in 2023 with two prototype satellites designed to track methane and CO.2 at the scale of individual installations.
In March, the United Nations Environment Program and the European Commission launched the International Methane Emissions Observatory to help coordinate these efforts and help policymakers and businesses take action. The observatory will also have access to estimated emission inventories from governments and industry. Around 70 oil and gas producers, including giants such as Shell and BP, have pledged to set clear emission reduction targets and report their emissions as part of an initiative led by the Climate & Clean Air Coalition , an international initiative involving governments, non-profit organizations, businesses and others. This work will also help inform new methane reduction commitments to be made at the United Nations climate conference in Glasgow, UK, in November.
The world will continue to heat up as long as CO2 is pumped into the atmosphere. But reducing emissions of methane and other potent greenhouse gases could reduce the sting. That is why governments and businesses should seize the opportunity, giving humanity a little more time to do what needs to be done.