Microbes are now the primary driver of methane emissions, according to CU Boulder researchers. Mitigating fossil fuel use and other human-related activities is still key to tackling climate change.
According to a new detailed analysis recently published in the Proceedings of the National Academy of Sciences by researchers from CU Boulder and their collaborators, the recent global surge in methane emissions is being driven by microbes in the environment rather than by fossil fuels.
“Understanding where the methane is coming from helps us guide effective mitigation strategies,” said Sylvia Michel, a senior research assistant at the Institute of Arctic and Alpine Research(INSTAAR) and a doctoral student in the Department of Atmospheric and Oceanic Sciences at CU Boulder. “We need to know more about those emissions to understand what kind of climate future to expect.”
Methane is a potent greenhouse gas responsible for about a third of the planet’s warming since industrialization. Although the atmosphere contains less methane than carbon dioxide, methane traps about 30 times more heat than carbon dioxide over a 100-year time frame, making it a critical target for addressing climate change.
“Methane concentrations in the air have almost tripled since the 1700s,” said co-author Jianghanyang (Ben) Li, an assistant professor in the Department of Atmospheric and Oceanic Sciences and INSTAAR.
But unlike CO2, which can stay in the atmosphere for thousands of years, methane degrades within a decade. As a result, addressing methane emissions can have an immediate and powerful impact in slowing the rate of warming, making it a “low-hanging fruit,” Li said.
While the finding suggests microbes have been emitting more methane than fossil fuels in recent years, reducing fossil fuel consumption remains key to addressing climate change, the team said. Cutting down food waste and consuming less red meat can also help lower one’s methane footprint.
ID the source
Previous research suggests fossil fuel production is responsible for about 30% of global methane emissions.
But microbial sources—such as wetlands, cattle, and landfills— are an even more significant source of methane, accounting for more than half of global emissions. Archaea, a type of microorganism living in soil and the guts of cows, produce methane as a byproduct of breaking down organic matter.
Michel and Li have been working with Boulder’s Global Monitoring Laboratory (GML) at the National Oceanic and Atmospheric Administration (NOAA) over the past years.
The lab receives air samples from 22 sites around the world every week or two. Researchers then isolate different components of the air—such as CO2 or methane—for analysis. By examining the types of carbon atoms, or isotopes, that the methane sample contains, Michel, Li, and the team can identify its source. For example, methane from fossil fuels has more carbon-13 isotope than methane in the air, and methane from microbial sources contains even less carbon-13. The lab has been measuring isotopes of methane since 1998.
Scientists have observed a rapid increase in atmospheric methane levels since 2007, following a period of stabilization in the early 21st century. In 2020, NOAA reported the highest growth rate of methane since it began collecting data in 1983, and that record was shattered again in 2021.
At the same time, Michel noticed a surprising decrease in the carbon-13 isotope over the past 17 years. She and the team set out to understand what was driving it.
The culprit
Using computer simulations, Michel and her team modeled three different emissions scenarios to see which one would leave an isotopic signature similar to the one observed.
They found that between 2020 and 2022, the drastic increase in atmospheric methane was driven almost entirely by microbial sources. Since 2007, scientists have observed microbes playing a significant role in methane emissions, but their contribution has surged to over 90% starting in 2020.
“Some prior studies have suggested that human activities, especially fossil fuels, were the primary source of methane growth in recent years,” said Xin (Lindsay) Lan, a scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU Boulder and NOAA. She leads the reporting on NOAA’s global greenhouse gas trends at the GML. “These studies failed to look at the isotope profile of methane, which could lead to a different conclusion and an incomplete picture of global methane emissions.”
It remains unclear whether the increased microbial emissions came from natural sources like wetlands or human-driven sources, such as landfills and agriculture. The team plans to delve deeper to identify the exact source of methane.
“In a warming world, it wouldn’t be surprising if any of these sources emitted more methane,” said Michel, who explained that microbes, like humans, tend to have higher metabolism when it’s warm. “Consequently, more methane could stay in the atmosphere to accelerate global warming. So we need to address the climate crisis, and that really means addressing CO2 emissions.”
Reference: “Rapid shift in methane carbon isotopes suggests microbial emissions drove record high atmospheric methane growth in 2020–2022” by Sylvia Englund Michel, Xin Lan, John Miller, Pieter Tans, J. Reid Clark, Hinrich Schaefer, Peter Sperlich, Gordon Brailsford, Shinji Morimoto, Heiko Moossen and Jianghanyang Li, 21 October 2024, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2411212121
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29 Comments
Could the rise in methane also be one of the results of Trump’s deregulation of methane in the US during his presidency?
no, did you read the article above?
Nah.
Too many people, i.e., over population, particularly coming from poor, ignorant countries – causes the majority of pollution. People are the cockroaches that cause pollution. Too afraid to say it? The population is 8.2 billion and doubles every 30 years. Ready for more cockroaches?
Bob
That population and poor countries narrative is a tired canard.
It’s the industrialized nations that put most of the CO2 into the atmosphere, that has accumulated since the industrial revolution. The U.S. is the #1 emitter of those cumulative emissions, about 2 times that of China and 8 times that of India. The EU is the #2 cumulative emitter of CO2.
The U.S. had the most annual CO2 emissions until China passed it in 2012.
The population problem is too often being used to suggest that efforts to cut emissions by switching to clean energy is futile. The same for the de-growth arguments against solving for climate change with technology. I’m all for getting off the consumerism on steroids treadmill, and have avoided it all my life, but it’s still a lame argument.
what is the methane isotope profile for methane freed from permafrost ? if that permafrost melt is due to global warming, then it still comes down to fossil fuel reduction as the key remediation, not landfills or wetlands which only adust the location of natural organic decay. feedlots are fine to be targeted along with fossil fuels.
Your correct on population, but your assumption that man is doing this is very wrong! There were no cities or factories 125,000 years ago when this last occured on Earth per ice cores and geology. Calling people cockroaches is insulting, demeaning, and offensive. Speak for yourself and ignorance like your assumptions makes me want to stomp on you. Squish!
“…, methane traps about 30 times more heat than carbon dioxide over a 100-year time frame, making it a critical target for addressing climate change.”
Once again, an ‘expert’ neglects to mention that the multiplier is based on equal weights of the two gases. Methane (CH4) has a much smaller molecular weight, so it takes far more molecules of CH4 to equal the weight of carbon dioxide (CO2). Both gases are measured commonly as a molar-fraction that is measured in parts per million-volume. On that basis, methane is increasing at an annual rate of about 0.01 ppmv, while CO2 is increasing less than 3 ppmv annually, or about 300X as fast. The annual increase in CO2 includes the CH4 that is converted to CO2. The anthropogenic CH4 growth is about an order of magnitude less than CO2, and it is impossible to eliminate all of it, even assuming an electric future. The impact of a concerted effort to reduce anthropogenic CH4 will be minuscule.
Please see the following for a more detailed explanation of the situation:
https://wattsupwiththat.com/2023/03/06/the-misguided-crusade-to-reduce-anthropogenic-methane-emissions/
wrong, the cumulative ghg gas effect would be the number of atoms times the ghg coefficient of the molecule. its the energy states of the electrons that is important. the molecular weight of the molecule is immaterial
you are wrong, the cumulative ghg gas effect would be the number of molecules( co2 or ch4) times the ghg coefficient of the molecule, which is different for co2 and ch4. its the energy states of the electrons that is important. the molecular weight of the molecule is immaterial. your reference is a joke, its oil industry propaganda,
I have no association, currently or formerly, with the oil industry. Do you have a citation you can provide that the “oil industry” has published anything even similar to what is in the link I provided? If not, then it is you who is providing propaganda.
Buffalo, Dinosaurs, methane must have been much more?
It is you who is wrong. The Global Warming Potential (GWP) of GHGs is DEFINED for an equal weight of gas, compared to CO2, albeit the absorption and re-emission is based on individual molecules. Therefore, the molecular weight is important because of the way it has been defined.
I take it that you didn’t bother to read the link I provided before responding.
REALLY? What’s Up With That?
You can’t be serious. Not at all a credible source
You are basically insulting me, because I am the author. I provided citations for all important claims. While one might be justified in being skeptical of a publisher that one subjectively doesn’t approve of, ultimately, it comes down to the facts and logic presented. It appears that, like “steve,” you didn’t bother to read the link either, or else you might have noticed that I was the author and important citations were provided.
surging methane is caused by population growth and economic growth in the developing nations, in the global south
It looks like you didn’t bother to read THIS article either.
this is good news for oil and gas producers
There used to be vast herds of buffalo in the US and similar herds of large animals in Africa. But now that they are gone we figure a few cows are bad. BS is what it is called.
No it is not good news for fossil fuels. Microbes emitting methane is likely coming from sources like melting permafrost etc. Caused by burning fossil fuels.
A few cows? How about maybe 30% of all mammals on the planet in tons of body mass?
Some studies have shown that over 60% of mammals in tons of body mass that still exist on the planet are pets and livestock. And cattle are over half of the livestock.
At any rate there are approximately 1.5 billion cattle in the world, one for every 5 people.
Bison migrated. They also had a symbiotic relationship with the prairie ecosystems and the totally different native grasses than now exist on the plains. Those native grasses had roots up to 5-8 feet deep, versus about 12 inches for human planted grasses.
That means they helped soil sequester and hold more carbon.
Bison’s diet was different than the diet of cattle livestock They sure as hell didn’t eat corn.
I don’t know, but it’s conceivable that they didn’t burp as much methane.
There is far more weight of cattle in the US than there was of Buffalo. You didnt even check the facts did you?
We have been talking about this for 30 years. Global warming caused by climate change is melting the tundra producing trillions of tons of methane.
In the tundra, atmospheric methane primarily originates from microbial sources within the soil, specifically from bacteria called methanogens that produce methane.
They found that between 2020 and 2022, the drastic increase in atmospheric methane was driven almost entirely by microbial sources…Yea, melting tundra!! In just 2 years? This is no surprise, ti is called a tipping point, the same is happening in the oceans, overload, can’t absorb more.
“But microbial sources—such as wetlands, cattle, and landfills— are an even more significant source of methane, accounting for more than half of global emissions”. Cows? really? what oil company wrote this?
I just really dislike seeing these types of headlines. One lame research project, incomplete at that, just dismissed 50 years of trying to get people to give a damn. Article should not be published until you have more complete findings. Like what about fossil fuel use driving climate change, melting ice and exposing the permafrost to thaw and release methane. How about SE Utah and all the methane released from the excessive drilling? The fossil fuel industry will love this article and will use this to justify what they do.
Very irresponsible reporting.
“Excessive drilling?” How do you define “excessive?” Are you happy with your increasing utility bills?
I suspect that you would be one of the first to complain if a preliminary report, supporting the “fossil fuels are bad” paradigm was NOT published because it was incomplete, or some anonymous person complained that it was “lame” for unspecified reasons.
Why is no one addressing the ever increasing release of methane into the atmosphere due to the melting of the permafrost in the Arctic?
Fossil fuels are behind it. With the increase in heat caused by fossil fuels you wouldn’t be getting this.
Actually, the official claim is that the GHGs are trapping IR emissions, acting like a blanket. The way you stated your claim makes it sound like the hydrocarbons themselves are responsible. Do you have any incontrovertible proof for either?