Global emissions of methane, a powerful greenhouse gas, rose to a record high in 2017, the latest year for which the world is available, researchers said on Tuesday.
And they warned that the increase – driven by fossil fuel and agricultural leaks – would certainly continue despite the economic slowdown from the coronavirus crisis, which is bad news for efforts to limit global warming and its severe effects.
The latest findings, published on Tuesday in two scientific journals, underscore how methane poses a growing threat, although the world finds some success in reducing carbon dioxide emissions, the most common greenhouse gas and the leading cause of global warming.
Researchers warn that if greenhouse gas emissions continue to increase on the current track, the world has little hope of limiting global warming to 1.5 degrees Celsius, or even 2 degrees Celsius. If the world warms beyond that, tens of millions of people could be exposed to life-threatening heat waves, freshwater shortages and coastal floods rising from sea level.
Methane, a colorless, odorless gas that is the main component of natural gas, is a powerful greenhouse gas that captures the sun’s heat and heats the earth 86 times as much as the same mass of carbon dioxide over a 20-year period.
And while the coronavirus pandemic led to a major temporary reduction in carbon dioxide emissions as much transportation and industrial land was stopped, there are signs that methane emissions have not dropped nearly as much, said Dr. Jackson.
“We still produce food. We still produce natural gas, he said. “If we continue to release methane as we have done in recent decades, we have no chance.”
In total, global methane emissions increased by 9 percent from the early 2000s, according to the latest results, and human activity is responsible for more than half of these emissions. Breeding livestock such as cattle and sheep, which burp large amounts of methane, is an important source of methane emissions, as is coal mining, which releases methane from deep inside the rock.
Methane also leaks from oil and gas wells, pipelines, distribution pipelines and even the gas furnaces in our homes and from landfills. The rest comes from natural sources, such as wetlands.
Of the anthropogenic emissions, agriculture accounts for about two thirds, while fossil fuels contribute most of the rest. However, the increase in emissions between 2000-17 came equally from agriculture, which increased almost 11 percent from the 2000-06 average, and fossil fuels, which increased almost 15 percent.
Methane emissions grew fastest in three regions: Africa and the Middle East; China; and South Asia and Oceania, including Australia. Heavy coal use caused methane emissions to jump in China, while population growth and rising incomes have led to more emissions elsewhere, the researchers say.
The United States has led to a significant increase in methane emissions from North America. About 80 percent of the total increase for the region was driven by fossil fuels, which underscores the environmental decline in the US slate boom.
Reducing methane emissions will require better plugging of leaks and other volatile emissions from oil and gas infrastructure, such as wells and pipelines, which are a major source of methane emissions, the researchers say. It will also require a review of agriculture, in particular cattle and rice farming, two major sources of methane emissions.
A major question mark is natural sources of methane emissions, such as wetlands, mud volcanoes and permafrost. Natural methane emissions have been relatively unchanged from 2000-17, albeit with large uncertainties.
For example, there is a fear that thawing permafrost in the Arctic could begin to release large amounts of methane into the atmosphere and further accelerate climate change. Currently, researchers have found little evidence of increasing methane emissions in the Arctic, although they warn that may change as warming intensifies. Scientists have warned that the Arctic region is warming for more than twice as much as the rest of the planet.
“The most important message is that methane concentrations and emissions are still rising, and we know the main reason,” said Marielle Saunois, a researcher at the Climate and Environmental Science Laboratory in France and a member of the research team. “This is not the way to go.”