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SUNDAY SCIENCE: MICROBES DROVE METHANE GROWTH BETWEEN 2020 AND 2022,
NOT FOSSIL FUELS  
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Yvaine Ye
October 21, 2024
Science Daily
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_ Microbes in the environment, not fossil fuels, have been driving
the recent surge in methane emissions globally, according to a new,
detailed analysis published Oct 21 in the Proceedings of the National
Academy of Sciences by CU Boulder researchers _

Microbes in aquatic and terrestrial environments produce and consume
the greenhouse gases CO2, CH4 and N2O. Soil and aquatic microbes
produce these gases when decomposing organic matter to provide
nutrients for plants and marine life, respectively., National Library
of Medicine

 

"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."

_Materials
[[link removed]] provided
by UNIVERSITY OF COLORADO AT BOULDER [[link removed]].
Original written by Yvaine Ye. Note: Content may be edited for style
and length._

_JOURNAL REFERENCE:_

_Sylvia Englund Michel, Xin Lan, John Miller, Pieter Tans, J. Reid
Clark, Hinrich Schaefer, Peter Sperlich, Gordon Brailsford, Shinji
Morimoto, Heiko Moossen, Jianghanyang Li. RAPID SHIFT IN METHANE
CARBON ISOTOPES SUGGESTS MICROBIAL EMISSIONS DROVE RECORD HIGH
ATMOSPHERIC METHANE GROWTH IN 2020–2022. Proceedings of the
National Academy of Sciences, 2024; 121 (44)
DOI: 10.1073/pnas.2411212121
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__

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By Carl Zimmer
New York Times
A study comparing chimpanzee and human brains suggests that the
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susceptible to aging.
August 28, 2024

* Science
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* Climate Change
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* biology
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* microbes
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* chemistry
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* Methane
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