One of the most potent greenhouse gases is rising faster than ever

Methane emissions from fossil fuels, farms and landfills will make it impossible for the world to maintain a safe climate, scientists say.

By Sarah Kaplan  September 10, 2024 at 2:00 a.m. EDT

Emissions of methane — a powerful greenhouse gas — are rising at the fastest rate in recorded history, scientists said Tuesday, defying global pledges to limit the gas and putting the Earth on a path toward perilous temperature rise.

New research from the Global Carbon Project — an international coalition of scientists that seeks to quantify planet-warming emissions — finds that methane levels in the atmosphere are tracking those projected by the worst-case climate scenarios. Because methane traps about 30 times more heat than carbon dioxide over a 100-year time frame, the accelerating emissions will make it nearly impossible for the world to meet its climate goals, the authors warned.

“These extra methane emissions bring the temperature thresholds ever closer,” said Rob Jackson, a Stanford University climate scientist and chair of the Global Carbon Project. “Warming that was once inconceivable is now perhaps likely.”

The project’s “Global Methane Budget” report, which has not yet been peer-reviewed, finds that human-caused methane emissions grew as much as 20 percent between 2000 and 2020 and now account for at least a third of total annual releases. The largest growth came from expanding landfills, booming livestock production, increased coal mining and surging consumption of natural gas.

The report also uncovered worrying evidence that human disruptions have boosted the amount of methane released by lakes, marshes and other ecosystems.

Since 2021, more than 150 countries have pledged to slash emissions of the gas by 30 percent by the end of this decade. But in a second, peer-reviewed study published in the journal Environmental Research Letters, Global Carbon Project researchers found little evidence that the world is making good on those promises.

Satellite measurements from more recent years revealed methane emissions grew an additional 5 percent between 2020 and 2023, with the biggest increases in China, southern Asia and the Middle East. Among major emitters, the study revealed, only the European Union has meaningfully curbed methane emissions in the last two decades.

Together, the two reports depict a world that has fallen critically short on controlling one of the most important contributors to climate change. Methane is responsible for about a third of the roughly 1.2 degrees Celsius (2.2 degrees Fahrenheit) of warming that has occurred since the late 1800s, according to the United Nations Intergovernmental Panel on Climate Change. And because the gas doesn’t linger in the atmosphere as long as carbon dioxide, it is considered a prime target for averting near-term temperature rise.

“It’s the only greenhouse gas where we can reduce climate change in the next decade or two through emissions reductions,” Jackson said.

Yet the inverse is also true, he added: As long as methane releases continue to grow, the world will feel dramatic and immediate temperature rise every year that methane releases continue to grow.

“We’re building a global consensus that we need to address methane,” said Environmental Defense Fund chief scientist Steven Hamburg, who was not involved in the Global Carbon Project research. “This is just one more clarion call that we gotta get on with it, and we gotta get on with it now.”

Observations from the National Oceanic and Atmospheric Administration show that methane concentrations in the atmosphere have more than doubled since the start of the industrial revolution and are now estimated to be at their highest level in at least 800,000 years. In contrast with carbon dioxide emissions, which have plateaued over the last decade, the accelerating rate of methane production matches what would be expected in the “high emissions” scenario used by scientists to project what might happen if humanity takes no action to combat climate change.

To assess where methane comes from, Jackson and his colleagues combined these “top down” measurements with “bottom up” estimates based on climate models. They also analyzed the chemistry of the gas to determine its source: Methane emitted by living creatures, such as microbes in landfills and marshlands, contains a different form of carbon than the version of the gas that comes from fossil fuels.

About a third of human-caused emissions comes from animal agriculture, particularly beef and dairy, the researchers found. Bacteria in the stomachs of Earth’s approximately 1.5 billion cows generate vast amounts of methane as they help the animals digest. More of the gas gets released by microbes as they break down the billions of tons of waste that livestock produce each year.

Despite efforts to address these emissions by changing cows’ diets and capturing manure fumes for fuel, the Global Carbon Budget showed that methane from livestock increased 16 percent from 2000 to 2020. Emissions from landfills grew even more, exploding 25 percent to account for one fifth of all human-produced methane.

Though the fossil fuel industry accounts for a smaller share of the world’s methane production than it did in 2000, emissions from coal mines, oil wells and gas pipelines have also seen significant increases. The Biden administration this spring finalized new fees on companies that don’t comply with new standards for curbing wasteful methane releases from oil and gas infrastructure. But those rules will only address a fraction of emissions from the country’s record oil production and booming gas sector, Jackson said.

“There’s no industry or segment of the U.S. economy that has reduced gas or methane emissions yet,” he added.

For the first time, the scientists also analyzed how human activities have affected the methane that comes from ecosystems, revealing that roughly a third of emissions that were once considered natural can actually be traced back to people. Runoff from farms and communities provides more nutrients for microbes in lakes and wetlands, accelerating their metabolisms and allowing them to produce more methane. Warmer temperatures and higher carbon dioxide concentrations in the air also give these organisms a boost.

Among the most problematic of these human-influenced natural sources are reservoirs behind dams, which the report says generate almost as much methane as all the world’s rice paddies. Organic material that would otherwise be carried by rivers out to sea becomes trapped in these lakes, where it is consumed by methane-producing microbes. When water is then pulled from the lake for generating hydropower or irrigating farmland, the methane gets released into the atmosphere.

This phenomenon doesn’t cancel out the climate benefits of switching from fossil fuel energy to hydropower, according to Jackson. But it highlights the urgency of understanding changes to ecosystem emissions.

“I’m worried that we’re setting in motion natural processes that we can’t control,” Jackson said.

Despite the accelerating rate of methane emissions, some research suggests that controlling the greenhouse gas could be cheaper than mitigating carbon dioxide — and it will deliver more immediate benefits. That effort is about to get a major boost from a fleet of orbiting observatories aimed at pinpointing the exact sources of methane, down to the nearest farm or gas facility.

“It’s really a revolution,” said Hamburg, who leads the Environmental Defense Fund’s MethaneSAT, which launched into orbit this spring. “We need to know where emissions are high, where emissions are low, who is doing a good job and who is not … so we can effectively hold people accountable.”

https://www.washingtonpost.com/climate-environment/2024/09/10/metha...