The Earth’s climate crisis is getting even worse than scientists feared, in part because of the amount of meat we eat and how we get around.
Global emissions of methane, a powerful greenhouse gas, have skyrocketed in the past decade, according to two new studies that have traced increasing sources of the colorless and odorless gas. Increasing methane, combined with carbon dioxide and other greenhouse gases, could heat Earth’s atmosphere by 3 to 4 degrees Celsius before the end of this century, significantly above levels that scientists have warned could be catastrophic for millions of people worldwide.
“This completely exceeds our budget to stay below 1.5 to 2 degrees warming,” said Benjamin Poulter, research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Poulter is the author of both studies published Tuesday, one in the journal Earth System Science Data and the other in the journal Environmental Research Letters.
Poulter and colleagues discovered that since 2000, the largest increases in methane emissions come from agricultural activities, particularly from livestock, such as cattle and sheep, and the fossil fuel industry, which includes coal mining and production. oil and gas.
Human activities account for about 60 percent of global methane emissions, according to the researchers. Agriculture accounts for about two-thirds of that, and the production and use of fossil fuels contribute most of the rest.
In the new studies, the researchers analyzed methane emissions from 2000 to 2017, the latest year for which complete global figures for methane are available, and found that Earth’s atmosphere absorbed a record 600 million tons of methane. in 2017. Annual methane emissions have also increased at a 9 percent annual rate since the early 2000s, a rate that could contribute more than 2 degrees Celsius of global warming by 2100.
A report released by the Intergovernmental Panel on Climate Change in October 2018 highlighted that the planet has already warmed 1 degree Celsius since the 19th century; used 1.5 degrees of warming above pre-industrial levels as a threshold beyond which the effects of climate change, including extreme heat and rising sea levels, endanger the lives of tens of millions of people in all the world.
Another author of both studies, Rob Jackson, a professor of earth system science at Stanford University, said the amount of methane released into the atmosphere since 2000 is roughly equivalent to adding 350 million more cars to the road.
In 2017, agriculture’s methane emissions increased by almost 11 percent from the 2000-06 average, while fossil fuel methane increased by almost 15 percent compared to the early 2000s.
Methane is released into the atmosphere when coal, oil, and natural gas are mined and transported, but microbes also emit it in low-oxygen environments.
“Anywhere where there is little or no oxygen (wetlands, paddy fields, landfills, a cow’s gut) are all sources of methane,” said Jackson.
Overall, methane makes up a much smaller percentage of global greenhouse gas emissions than carbon dioxide, but it is of particular concern to scientists because the molecular structure of methane makes it more readily capable of absorbing radiation. thermal.
“Methane doesn’t last as long in the atmosphere as carbon dioxide, but it is much more efficient at trapping heat than carbon dioxide,” said Poulter, who makes gas a key factor in global warming.
To curb methane emissions, countries must reduce their dependence on fossil fuels, in addition to reducing the number of harmful leaks from pipes and wells, Jackson said.
Scientists are also studying how to minimize methane emissions in farming practices, such as altering water levels in paddy fields and experimenting with changes in the diets of cattle and sheep to reduce the amount of methane belched from their digestive systems. Burger King recently announced that it will add lemongrass to their cows’ diet to reduce methane emissions with a low-carb diet.
But reducing greenhouse gas emissions will also require further changes in human behavior, Jackson said.
“Diet matters,” said Jackson. “Here in the United States, we have one of the highest rates of red meat consumption in the world. We don’t necessarily have to stop eating red meat, but eating less meat or eating more fish and chicken instead of beef will reduce emissions, too. “
And while the coronavirus pandemic is expected to produce a significant decrease in carbon dioxide emissions in 2020, primarily due to the economic slowdown and blockages that dramatically reduced air travel and other transportation, no similar decreases are anticipated with the methane.
“Our farmers are still producing food, oil and gas production has not yet slowed much, and methane plays a very small role in the transportation sector,” said Jackson. “So while we can see a small decrease this year due to the coronavirus, methane emissions over the past decade are going up. And at this rate, we won’t see a peak of methane emissions any time soon.”
