Global emissions of methane, a powerful greenhouse gas, soared to a record high in 2017, the most recent year for which global data is available, researchers said Tuesday.
And they warned that the increase, fueled by fossil fuel leaks and agriculture, will surely continue despite the economic slowdown of the coronavirus crisis, which is bad news for efforts to limit global warming and its serious effects.
The latest findings, published Tuesday in two scientific journals, underscore how methane poses a growing threat, even as the world finds some success in curbing emissions of carbon dioxide, the most abundant greenhouse gas, and the leading cause of warning. global.
“There is a hint that we could reach maximum carbon dioxide emissions very soon. But it looks like we’re not even close to the methane spike, “said Rob Jackson, an Earth scientist at Stanford University who runs the Global Carbon Project, which conducted the research.. “It is not decreasing in agriculture, it is not decreasing with the use of fossil fuels. “
Scientists caution that if greenhouse gas emissions continue to rise on the current trajectory, the world has little hope of limiting global warming to 1.5 degrees Celsius, or even 2 degrees Celsius. If the world warms up beyond that, tens of millions of people could be exposed to life-threatening heat waves, a shortage of fresh water and coastal flooding due to rising sea levels.
Methane, a colorless, odorless gas that is the main component of natural gas, is a powerful greenhouse gas that traps heat from the sun and heats the earth 86 times more than the same mass of carbon dioxide over a period of 20 years.
And while the coronavirus pandemic caused a large temporary drop in carbon dioxide emissions, as both transportation and industry stopped, there are signs that methane emissions have not decreased as much, Dr. Jackson said.
“We are still producing food. We are still producing natural gas, “he said. “If we continue to release methane as we have in the past decades, we have no chance.”
Overall, global methane emissions have increased 9 percent since the early 2000s, according to the latest findings, and human activity is responsible for more than half of those emissions. Livestock farming such as beef and sheep, which burp large amounts of methane, is a major source of methane emissions, as is coal mining, which releases methane from deep within the rock.
Methane also leaks from oil and gas wells, pipelines, distribution lines, and even gas stoves in our homes, and from landfills. The rest comes from natural sources, such as wetlands.
Of anthropogenic emissions, agriculture accounts for about two thirds, while fossil fuels contribute most of the rest. However, the increase in emissions between 2000-17 also came from agriculture, which increased almost 11 percent from the 2000-06 average, and fossil fuels, which increased by almost 15 percent.
Methane emissions grew fastest in three regions: Africa and the Middle East; China; and South Asia and Oceania, including Australia. An increase in coal use caused an increase in methane emissions in China, while population growth and rising incomes have led to more emissions elsewhere, the scientists said.
The United States has led a significant increase in methane emissions from North America. About 80 percent of the region’s total increase was fueled by fossil fuels, underscoring the environmental consequences of the U.S. oil shale boom.
Reducing methane emissions will require better plugging leaks and other fugitive emissions from oil and gas infrastructure, such as wells and pipelines, which are a major source of methane emissions, the scientists said. It will also require a review of agriculture, especially livestock and rice cultivation, two major sources of methane emissions.
A major question mark is the contribution of natural sources of methane emissions, such as wetlands, mud volcanoes, and permafrost. Natural methane emissions have remained relatively unchanged since 2000-17, albeit with large uncertainties.
It is feared, for example, that the melting of permafrost in the Arctic may begin to release large amounts of methane into the atmosphere, further accelerating climate change. For now, scientists have found little evidence of increased methane emissions in the Arctic, although they caution that it could change as warming intensifies. Scientists have warned that the Arctic region is warming at more than double the rate of the rest of the planet.
“The key message is that methane concentrations and emissions continue to rise, and we know the root cause,” said Marielle Saunois, a scientist at the Laboratory for Climate and Environmental Sciences in France, and a member of the research team. “This is not the right way.”
