Levels of methane in the atmosphere increased last year by the largest amount since measurements began four decades ago, government scientists said on Thursday, adding to concerns about the planet-warming gas, which spews from oil and natural gas operations.
Methane is less abundant in the atmosphere than carbon dioxide, but it is more potent in its near-term effects on global warming. Large amounts of methane pour into the air from wells and pipelines, sometimes through unintentional leaks. Other sources include livestock, landfills and the decay of organic matter in wetlands.
Atmospheric concentrations of methane have increased steadily over the past 15 or so years, and in 2021, they rose by a record amount over the year before, reaching a new high, according to preliminary analysis by the National Oceanic and Atmospheric Administration. The previous record for annual increase in methane levels had been set in 2020.
“Our data show that global emissions continue to move in the wrong direction at a rapid pace,” said Richard W. Spinrad, the NOAA administrator. “Reducing methane emissions is an important tool we can use right now to lessen the impacts of climate change in the near term, and rapidly reduce the rate of warming.”
Surging methane emissions in recent years have brought increasing attention to the gas’s role in accelerating climate change.
Carbon dioxide still contributes much more to the warming of the planet over all. The NOAA analysis published on Thursday indicates that levels of carbon dioxide also continued to rise rapidly in 2021. During the past 10 years, carbon dioxide concentrations grew at their quickest pace in the six-plus decades since monitoring began, NOAA said.
However, because of how much more methane contributes to warming over shorter periods of time, scientists regard reducing methane emissions as a way to curb warming more rapidly.
And, unlike carbon dioxide, which is released into the atmosphere when fossil fuels are burned for energy, methane is the main component of natural gas, which means emitters have economic reasons not to let too much of it be released into the air through leaks. The energy industry accounts for about a third of global methane emissions, scientists estimate.
Apart from trapping heat at Earth’s surface, methane also contributes to ground-level ozone pollution, which can cause breathing problems and other health issues. By NOAA’s estimates, methane is now over two and a half times more abundant in the atmosphere than it was before the Industrial Revolution.
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At a global climate summit last year in Glasgow, more than 100 nations joined together and pledged to slash global methane emissions 30 percent by 2030. The Biden administration has announced new rules governing methane from oil and gas rigs across the United States.
One factor that may have contributed to the rapid growth in methane emissions during the past two years might be increased rainfall in tropical regions resulting from the climate phenomenon known as La Niña, said Xin Lan, an atmospheric scientist at the NOAA Global Monitoring Laboratory in Boulder, Colo.
The added rain and moisture may have led to increased methane production by microbes living in tropical wetlands, she said. These micro-organisms are also more active in warmer weather, she said, so natural emissions from wetlands and other places may be generally increasing as the planet heats up.
Even so, limiting leaks from fossil fuel facilities should be an easier way to stabilize methane levels than trying to manipulate rainfall in the tropics, Dr. Lan said. “Fossil-fuel methane emission reduction seems to be low-hanging fruit to us,” she said, particularly given that emitters could be using this methane as fuel and making money from it.
That leaked methane is “a waste of pure energy,” Dr. Lan said. “It shouldn’t be there in the atmosphere.”