Human activities are responsible for two-thirds of global methane emissions

New research warns that the world is heading in a dangerous direction in terms of planet-warming methane emissions, which are rising to record highs mainly due to human activities.

Although many people associate methane with cow belching And Melting permafrostA paper published this week in the journal Earth System Science Data The study found that global methane emissions have risen faster than ever before over the past five years – and at least two-thirds of emissions are now coming from human sources.

In April of this year, methane concentrations reached 1,000 ppg. Record height 1,931 parts per billion — an increase of 11 ppb over last year.

Experts said the findings were extremely worrying, as they put the planet on track to reach the desired limit of 2.7 degrees Celsius of pre-industrial temperature rise – an international benchmark often used to measure temperature. 1.5 °CIn fact, methane contributed to about 1 degree of global temperature rise in the 2010s.

“In terms of the contribution of methane, we’re on a trajectory that’s consistent with about 3 degrees Celsius right now,” said study lead author Rob Jackson, who is also a climate scientist at Stanford and president of the International Conference on Climate Change. Global Carbon Project“If you just look at methane we are a long way from 1.5 or even 2 degrees Celsius.”

A 3 degree Celsius scenario — about 5.4 degrees Fahrenheit — would have potentially catastrophic consequences, including accelerated melting of ice sheets, longer heat waves and droughts, water shortages, famine, and political and social unrest, among other consequences outlined by the Intergovernmental Panel on Climate Change.

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But although methane is capable of warming 30 to 80 times more than CO2, it also has one advantage: it is relatively short-lived. Methane lasts about a decade in the atmosphere, while CO2 lives for hundreds of years or even longer.

“It’s really the only way we can reduce warming in the next decade or two,” Jackson said. “We can’t really do anything about the trillions of tons of carbon dioxide that are in the air in that time frame, but for methane, we could see concentrations return to pre-industrial levels within a decade if we could wave a magic wand and stop anthropogenic emissions.”

“This is unlikely to happen soon, but it should be our goal. Doing so will help us reduce the temperature by at least half a degree Celsius,” he said.

The sources of methane emissions can be broadly divided into two categories: human sources, which result mainly from agriculture, fossil fuels, landfills and waste; and natural sources such as wetlands, swamps and marshes, which emit methane when bacteria decompose organic matter.

The paper found that emissions from both categories are rising, though human sources appear to be producing a larger and larger share, now accounting for about 65% of projected emissions, compared with 60% in 2020, Jackson said. (The actual proportion could be even higher depending on how emissions from some sources, such as dams and reservoirs, are classified.)

However, there is also growing concern about methane emissions from natural systems.

rising global warming Microbial activity is increasing in tropical hot spots such as the Congo, the Amazon and Southeast Asia, emitting more methane, which in turn could lead to more warming in a worrying feedback loop, Jackson said.

“The fact that everything is still increasing is troubling. However, the most worrying thing for me is the possibility of natural emissions increasing, especially in the tropics,” he said. “We think we’re starting to see it, but we’ll really know in the next four or five years – and if it starts to happen on a large scale that’s really bad news.”

Arctic permafrost – or soil that was once permanently frozen – is also soil that remains perpetually frozen. Melting amid record high global temperatures and releasing carbon and methane into the atmosphere.

Evan Sherwin, a research scientist at Lawrence Berkeley Laboratory who was not involved with the study, said its findings are significant and sweeping, though not entirely surprising.

“This is a very stark reminder to us — especially given that a lot of efforts have been made to reduce methane emissions — that the share of methane emissions from anthropogenic sources appears to be increasing,” Sherwin said.

He said there is still uncertainty about where the planet is headed in terms of temperature rise, especially because humanity has a great deal of control over its emissions between now and the end of the century.

Agriculture is just one of many human-caused sources of methane. Here, Holstein cows are loaded up at a California dairy farm.

(Mel Melcon/Los Angeles Times)

But if methane emissions continue to rise at roughly the current rate, and CO2 emissions are not cut as rapidly as they should be, a 3 degree Celsius temperature rise “doesn’t seem impossible to me at all,” he said.

Like Jackson, he said the potential for increased emissions from natural sources is worrying and requires additional study, especially in relation to tropical ecosystems.

However, he added, methane emissions from human sources are not increasing worldwide. In Europe, for example, emissions have fallen significantly over the past two decades, while emissions in Korea, Japan and Australia have remained roughly the same, the study shows. (Comprehensive calculations for the United States show an overall increase over that time frame.)

“This is an indication that it is possible to keep methane emissions stable, or even reduce emissions substantially, which I think is a promising sign,” Sherwin said.

In fact, the finding that humans are now the main driver of methane emissions could in some ways be seen as a positive aspect, because it can potentially be reduced or controlled, Sherwin said.

“If we make a massive effort to reduce methane emissions — and I should say nitrous oxide and other short-lived greenhouse gases as well — we can give ourselves decades to reduce carbon dioxide emissions.”

Such efforts are underway. The most promising are new rules from the US Environmental Agency that Strengthening emissions reporting requirements Power generation from oil and natural gas facilities is being promoted in the hopes of reducing methane and other pollutants.

Last year, California passed a landmark law that requires large U.S. companies doing business in the state to set a certain deadline to sell their products. Disclose your annual greenhouse gas emissions Starting in 2026, this will be the first such rule in the country.

State bills Plugging orphan oil wells and setting methane emissions targets Dairy and Livestock Producers Efforts to get electricity into homes and buildings can also make a difference, said Jackson, who recently wrote an article about how the power supply can be powered by electricity. Book on Clean Energy Transition,

But such efforts cannot deny the fact that emissions are rising at an alarming rate. Global Methane Pledge The agreement, signed by 158 countries, including the U.S., aims to reduce global methane emissions by at least 30% from 2020 levels by 2030, but “that hasn’t even really started to happen yet,” Jackson said.

“No greenhouse gas has decreased in the atmosphere yet, and for gases like methane, levels are rising faster than before,” he said. “This cannot continue for a habitable planet. It looks like we’re heading toward 3 degrees Celsius, which is a frightening prospect, and I hope that’s wrong.”