Climate & Environment

A vicious cycle: How methane emissions from warming wetlands could exacerbate climate change

Yvaine Ye — Thu, 15 May 2025 17:34:29 +0000

A vicious cycle: How methane emissions from warming wetlands could exacerbate climate change Yvaine Ye Thu, 05/15/2025 - 11:34

Yvaine Ye

Warming in the Arctic is intensifying methane emissions, contributing to a vicious feedback loop that could accelerate climate change even more, according to a new study published May 7 in Nature.

“Methane is a very potent greenhouse gas that we need to address urgently,” said co-author Xin (Lindsay) Lan, a climate scientist at �山��’s Cooperative Institute for Research in Environmental Sciences (CIRES). “Our study suggests that a significant portion of the recent rise in atmospheric methane originates from natural sources driven by climate change. Our emission reduction efforts need to be more aggressive.”

Xin (Lindsay) Lan

Methane is the second most abundant human-produced greenhouse gas after carbon dioxide. But an equal amount of methane traps about 30 times more heat than CO₂ over a 100-year time frame. Methane has been responsible for roughly a quarter of the planet’s warming since the Industrial Revolution.

Lan has spent the past decade tracking methane concentrations in the atmosphere at �山��’s Global Monitoring Laboratory at the National Oceanic and Atmospheric Administration (NOAA).

Lan and her colleagues at NOAA have observed a rapid increase in atmospheric methane levels in recent years. While previous studies have shown fossil fuel production accounts for 30% of global methane emissions, Lan and colleagues have noticed a steady increase in emissions from microbial sources since 2007.

These microbes, specifically a group known as archaea, produce methane as a byproduct of their metabolism in environments like wetlands, landfills and livestock’s digestive systems.

Together, microbial emissions contribute to nearly half of global methane emissions, but it remains unclear which specific sources are driving this increase.

“While long-term methane trends are important to investigate, we also need to look at seasonal variations to understand how individual sources are changing and how the natural mechanisms that remove methane from the atmosphere are evolving,” Lan said.

A vicious cycle

To get a clearer picture, Lan and her team analyzed seasonal fluctuations in atmospheric methane levels over the past four decades.

They found that methane’s seasonal amplitude — the difference between peak and lowest methane levels within a year— has been decreasing in northern high-latitude regions, including the Arctic.

Using computer models, the team showed that this trend since the 1980s is largely a result of increased methane emissions from wetlands. Increased precipitation in the Arctic has expanded the region’s wetlands by 25% during the warmer months. Rising temperatures have also been melting some of the perpetually frozen soil layer deep underground, known as permafrost, in summer.

Our hope is that by rapidly reducing emissions, we can avoid triggering more severe and abrupt climate feedback that could lead to catastrophic events.

The melted, waterlogged soils have provided ideal conditions for archaea to thrive, leading to higher methane emissions which in turn could accelerate warming further.

Scientists have long warned about such climate feedback loops, but the precise scale and speed of these effects remain uncertain. Lan said this new study added another piece of evidence that natural methane emissions have already been responding to a warming climate.

“This study, along with a few previous studies, has provided indirect evidence on potential climate feedback on methane emissions, which would be beyond our ability to control directly,” Lan said.

The sharp increase in atmospheric methane and its climate feedback effects since 2007 resemble the planet’s most dramatic warming events that brought past ice ages to an end, according to Lan’s previous research.

“Our hope is that by rapidly reducing emissions, we can avoid triggering more severe and abrupt climate feedback that could lead to catastrophic events,” she said.

Methane sponges

The team’s simulations also found a 10% increase in the levels of hydroxyl (OH) radical since 1984. These radicals are highly reactive molecules that can soak up and remove methane and other air pollutants.

Because these molecules stay in the air for less than a second before they react with other compounds, scientists cannot directly measure them globally. In the past, researchers had assumed the OH levels remained constant over the years when calculating atmospheric methane emissions, but this study suggested that assumption might be wrong.

“Our result showed that we’ve been underestimating how much methane the atmosphere has been removing, which means that there’s actually more methane being emitted than we previously estimated,” Lan said.

Understanding the specific source of emission is vital in designing climate mitigation policies. While microbial emissions are responsible for most of the methane growth, human-produced methane from burning fossil fuels remains an important contributor.

“We need to aggressively cut all greenhouse gas emissions from the sources we can control,” Lan said. She added that the world’s permafrost currently holds at least twice as much carbon as is currently in the atmosphere. If future warming causes widespread permafrost thaw and releases that carbon, it could trigger irreversible changes to the planet’s climate. “We need to address the feedback loop before reaching that tipping point.”

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The latest study finds that emissions of the potent greenhouse gas might be higher than previously estimated.

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Landscape of wetlands and snowy mountains of Arctic National Wildlife Refuge. (Credit: Lisa Hupp/USFWS)

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Landscape of wetlands and snowy mountains of Arctic National Wildlife Refuge. (Credit: Lisa Hupp/USFWS)

Pacific upwelling much faster at the equator than scientists thought

Megan Maneval — Fri, 09 May 2025 15:32:29 +0000

Pacific upwelling much faster at the equator than scientists thought Megan Maneval Fri, 05/09/2025 - 09:32

CIRES

A new discovery by a �山�� researcher shows why global climate models overestimate warming in the tropical Pacific Ocean.

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Arctic plants react unexpectedly to climate change, study says

Megan Maneval — Fri, 09 May 2025 15:25:12 +0000

Arctic plants react unexpectedly to climate change, study says Megan Maneval Fri, 05/09/2025 - 09:25

INSTAAR

A team of 54 researchers, including Sarah Elmendorf, analyzed more than 42,000 field records of Arctic plant communities over a span of 41 years. Their insights are essential to understanding how Arctic environments are changing in the modern era.

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CUriosity: Why, and how, do ants walk in a perfect line?

Yvaine Ye — Tue, 06 May 2025 17:52:44 +0000

CUriosity: Why, and how, do ants walk in a perfect line? Yvaine Ye Tue, 05/06/2025 - 11:52

Yvaine Ye

In CUriosity, experts across the �山�� campus answer pressing questions about humans, our planet and the universe beyond.

This week, entomologist Julian Resasco answers: “Why, and how, do ants walk in a perfect line?”

A group of ants walking in a line. (Credit: Jithin Vijayamohanan/Unsplash)

In the world of ants, order isn’t optional. These tiny insects live in colonies with millions of others, working together as a team to forage, defend their nests and care for their young.

As spring arrives, ants emerge from their winter hiding places and quickly organize themselves into perfect lines, weaving across patios, yards and kitchen floors in search of food for the colony.

Ants are some of the best team players in the natural world, and keeping such a large organization running takes a special kind of communication, said Resasco, assistant professor in the Department of Ecology and Evolutionary Biology. Most of the time, these insects reply on chemical scents, called pheromones, to exchange information with each other. That includes where to find food.

Julian Resasco

When an ant finds a promising snack, it marks its path with pheromones as it heads back to the colony. Fellow ants follow the trail by picking up the scent using sensors often in their antennae. They also lay down more of the same scent along the way to strengthen the trail.

Generally, ants don’t see very well compared to humans. Instead, the pheromone trails help them navigate without getting lost. That’s why they march in a nearly perfect line.

Depending on how good the food source is, ants may choose to secrete pheromones that can stick around for a long time so they can recruit a larger group to help carry it. They could also lay down pheromones that evaporate quickly if the food is subpar or can be quickly gathered up.

“If you look at any individual ant and what they're doing, they seem really dumb,” said Resasco, who has been studying ants, including the notorious fire ants that give people painful stings, for over a decade. “But as a colony, a sum of all these very simple behaviors, they can do pretty amazing and complex things.”

In addition to marking the path to a food source, ants can also secrete chemical signals to alert others in the colony of an approaching enemy.

Previously in CUriosity

Can humans handle the stress of traveling to Mars?

Or read more CUriosity stories here

Different species of ants have different ways of forming their foraging routes. For example, leafcutter ants can build organized lanes of traffic: One lane going up tree branches to the food source and another for those returning with the harvest. Army ants, commonly found in Central and South America, assemble themselves into massive, moving swarms to raid other insect colonies for resources.

“If you see these ant swarms in the rainforests, it looks like the ground is moving,” Resasco said.

But the system isn’t foolproof. If an army ant swarm hits an obstacle, or a small group loses the pheromone track, they may start following one another in a continuously rotating circle called a death spiral. As the name suggests, the spiral ends only when the ants die of exhaustion.

“Ants are the little things that run the world. They're extremely abundant, and they do really important things for our ecosystems and agriculture, such as turning over soil and eating other insects that may be pests,” Resasco said.

He recommended that following a trail of ants and observing what they do could be a fun activity for a sunny afternoon.

“Ants are virtually everywhere we look, and if we pay attention to them, they’re always doing interesting things.”

In CUriosity, experts across the �山�� campus answer pressing questions about humans, our planet and the universe beyond.

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Researchers capture snapshots of a fundamental continent‐building process

Megan Maneval — Fri, 02 May 2025 19:12:09 +0000

Researchers capture snapshots of a fundamental continent‐building process Megan Maneval Fri, 05/02/2025 - 13:12

CIRES

CIRES-led research found evidence that dense portions of Earth's lithosphere (its top layer of rock) are peeling off and dropping into the mantle below the Sierra Nevada mountains.

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The ocean may be absorbing less carbon, but it may not be due to climate change—yet

Yvaine Ye — Tue, 29 Apr 2025 16:06:10 +0000

The ocean may be absorbing less carbon, but it may not be due to climate change—yet Yvaine Ye Tue, 04/29/2025 - 10:06

Yvaine Ye

The ocean has absorbed about 30% of carbon dioxide emissions from human activities since the Industrial Revolution, significantly slowing the pace of climate change.

But as emissions continue to rise, scientists have warned that the ocean could eventually become too saturated with carbon to absorb more. Has the day arrived?

Using a computer simulation, �山�� oceanographer Nicole Lovenduski and her collaborators found that the recent slowdown in the ocean’s carbon absorption is likely a result of natural fluctuations instead of human-driven climate change. The study was published in Environmental Research Letters.

Nicole Lovenduski/�山��

“The ocean has been doing us this huge favor for so long by taking up man-made carbon,” said Lovenduski, director of the Institute of Arctic and Alpine Research and professor in the Department of Atmospheric and Oceanic Sciences.” If less is going into the ocean, that means more is left in the atmosphere.”

Scientists previously found that between 2004 and 2014, the ocean absorbed about 2 gigatons less human-generated, or anthropogenetic, carbon than it did between 1994 to 2004, even though the atmospheric carbon levels had continued to rise over the past decades. This amount is roughly one-third of the U.S.’ annual carbon emissions.

“Generally, when there’s more carbon in the atmosphere, the ocean would try to take up more to maintain its chemical equilibrium,” Lovenduski said.

But climate models have suggested that once the planet warms up above a certain point, the ocean would start to absorb less carbon. This is because warm water takes up less CO2 than cold water. Warmer temperatures also slow down ocean currents that help bring cold seawater from Earth’s colder regions to the tropics and from the deep sea to the surface.

Scientists were unsure if the slowdown since 2004 was a result of global warming.

Measuring anthropogenic carbon concentrations in the ocean is no small feat. Lovenduski and other oceanographers have gone out on boats to drop large bundles of roughly 30 canisters into designated spots across all five oceans to collect water samples from different depths.

Holly Olivarez (front) and colleagues during a survey expedition in 2021. (Courtesy of Holly Olivarez)

Because these surveys are time-consuming and labor-intensive, scientists only conduct them once every decade.

That means that, by chance, the ocean could be experiencing special conditions during the sampling years, Lovenduski said. Some of these natural fluctuations could influence how much carbon the seawater absorbs. For example, during an El Niño event, less carbon-rich water from the deep ocean rises to the surface in the tropical Pacific Ocean, which means measurements taken during such event could complicate estimates of how much carbon the ocean is absorbing.

Lovenduski and her team set out to investigate the causes of the recent slowdown in ocean carbon uptake.

The research team, including first author, Holly Olivarez, who was a graduate student at �山��, used a computer model to simulate how forces outside the oceans, such as rising atmospheric CO2 and volcanic eruptions, and internal factors, like El Niño events, have influenced how much carbon the ocean took up between 1994 and 2014.

When the model only considered external factors, the ocean’s carbon storage continued to rise in step with anthropogenic emissions. The growth rate only slowed when the team added the effects of internal factors to the model. The impact of forces like El Niño events was particularly prominent in places like the tropical Pacific Ocean, subpolar North Atlantic Ocean and the Southern Ocean.

Scientists drop bundles of roughly 30 canisters into designated spots across all five oceans to collect water samples from different depths. (Courtesy of Holly Olivarez)

“It turns out that the way we measure the ocean could have imparted that change in carbon storage growth rate,” Lovenduski said. “Maybe the slowdown from climate change is already happening, but our paper suggests that we need to rule out the internal factors before we can say that with confidence.”

She added that the study highlights a major gap in ocean monitoring. Scientists sample the atmosphere hourly, but the chemistry of the ocean only once a decade. Without a more accurate picture of how much carbon the ocean is absorbing, it would be difficult to estimate how fast the planet is truly warming.

“We are only measuring a tiny little sliver of the ocean, and we're only doing it once every 10 years. We need to fill the location gap and time gap,” she said.

Lovenduski hopes that in the future, scientists can deploy autonomous robots to different parts of the ocean to analyze anthropogenic carbon concentrations in seawater. The technology will allow them to measure carbon levels in the ocean continuously and across more locations.

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A recent �山��-led study finds that recent dips in the ocean’s carbon absorption are likely due to natural variability instead of global warming.

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Credit: Cristian Palmer/Unsplash

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Credit: Cristian Palmer/Unsplash

Melting glaciers at the end of the Ice Age may have sped up continental drift, fueled volcanic eruptions

Daniel William Strain — Thu, 24 Apr 2025 03:03:00 +0000

Melting glaciers at the end of the Ice Age may have sped up continental drift, fueled volcanic eruptions Daniel William… Wed, 04/23/2025 - 21:03

Daniel Strain

A glacier flows into the sea from modern-day Greenland. (Credit: CC photo via Flickr)

Around 10,000 years ago as the last Ice Age drew to a close, the drifting of the continent of North America, and spreading in the Atlantic Ocean, may have temporarily sped up—with a little help from melting glaciers, according to a new study from scientists at the �山��.

In the new research, geophysicists Tao Yuan and Shijie Zhong used computer simulations, or models, to travel back roughly 26,000 years into the planet’s past. At the time, the massive Laurentide Ice Sheet, which stretched over North America as far south as Pennsylvania, started to recede. Melting ice flooded into the oceans, and sea levels worldwide rose by an average of around 1 centimeter per year.

The Laurentide Ice Sheet at its maximum extent during the last Ice Age. (Credit: Dalton et al., 2022, Earth-Science Reviews)

Graphic showing the Mid-Atlantic Ocean Ridge (red line) and how melting ice from Greenland caused changes in the motion of Earth's crust (purple arrows). (Credit: Tao Yuan and Shijie Zhong)

Fagradalsfjall volcano erupts in Iceland in 2023. (Credit: CC photo by Giles Laurent via Wikimedia Commons)

The scientists discovered that this global thaw may have also had unexpected consequences—including for plate tectonics, or the internal clockwork that has, for billions of years, torn Earth’s continents apart and crushed them together.

According to the team’s calculations, the motion of the North American continental plate may have sped up by 25% as the ice melted. At the same time, spreading at the Mid-Atlantic Ocean Ridge, which sits between the North American and Eurasian plates, may have increased by as much as 40%.

“As ice volume was greatly reduced, it caused a huge motion in Earth’s crust,” said Yuan, a graduate student in the Department of Physics at �山��. “Scientists knew that the ice melting caused the plates to uplift. But we show that they also moved a lot horizontally due to the ice melting.”

The researchers published their findings April 23 in the journal Nature.

Their results may have implications for the planet today. Ice sheets over Greenland are once again melting at a rapid rate, which, in a strange twist, could drive an increase in volcanic eruptions in Iceland not far away.

“That story that we’ve been telling for a long, long time—that processes like seafloor spreading and continental drift operate at timescales of millions of years driven by Earth’s internal engine—thermal convection,” said Zhong, a professor of physics. “That’s still true, but we show that glacial forcing can also cause significant motion on relatively short timescales of 10,000 years.”

Moving gears

The research, which was funded by the U.S. National Science Foundation, takes a deep dive into the Mid-Atlantic Ocean Ridge. This feature runs for thousands of miles down the center of the Atlantic Ocean and cuts through the island of Iceland. It’s a turbulent place: There, magma from deep within the planet bubbles up through the crust, cooling into solid rock and helping to force the continents of North America and Europe away from each other.

For generations, scientists believed that this process was largely steady—with the ridge spreading by a consistent 2 centimeters every year for the past several million years.

“That’s a fairly well-known, textbook number,” Zhong said.

But could the textbooks be wrong?

To find out, Zhong and Yuan used computer models to recreate the Earth as it was thousands of years ago. The researchers simulated what might happen as glaciers that were kilometers thick disappeared from modern-day Canada and Greenland—shifting that weight off dry land and into the ocean.

It helps to picture the globe as a memory foam mattress. If you’re lying on a mattress and get up, the foam will slowly bounce back to its original shape. Something similar happened on Earth as ice sheets melt, Zhong and Yuan said.

As the weight of the Laurentide Ice Sheet was redistributed around the planet, parts of North America began to bounce back up. (Today, land around Canada’s Hudson Bay is still rising by around 1 centimeter per year because of that rebound). According to the new study, the melting may have also affected the horizontal motion of North America and the Mid-Atlantic Ocean Ridge.

Volcanic eruptions

The thaw may also have had explosive consequences for Iceland, which sits close to Greenland, Yuan and Zhong said.

Geological evidence, for example, suggests that the island underwent a period of intense volcanic activity at the end of the last Ice Age, which has since quieted down. Enhanced spreading at the Mid-Atlantic Ocean Ridge due to ice melting from Greenland may have contributed to that fiery past—allowing more magma to rise to the surface, fueling the eruption of volcanoes and geysers.

“This pattern of volcanism may have been partly due to the glacial melting that we studied,” Zhong said.

Today, ice over Greenland isn’t melting fast enough to have much of an impact on the planet’s continental drift. But it could still have a major influence on Iceland over the next several hundred years, especially if glaciers begin to disappear at an accelerating rate.

“Ice sheets in Greenland and West Antarctica are still melting,” Yuan said. “We think the ice melting could enhance seafloor spreading and volcanism at nearby mid-ocean ridges in the future.”

Ice melting from modern-day Greenland could again drive an increase in volcanic eruptions around Iceland, a new study suggests.

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Climate change is transforming how scientists think about their roles

Megan Maneval — Tue, 22 Apr 2025 16:05:15 +0000

Climate change is transforming how scientists think about their roles Megan Maneval Tue, 04/22/2025 - 10:05

Colorado Arts and Sciences Magazine

�山�� researcher Pedro DiNezio emphasizes solving the problems of climate change in the here and now.

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Colorado’s snowpack lagging behind the 21st century average

Megan Maneval — Thu, 17 Apr 2025 20:47:23 +0000

Colorado’s snowpack lagging behind the 21st century average Megan Maneval Thu, 04/17/2025 - 14:47

INSTAAR

A new modeling tool from INSTAAR provides weekly snow-water equivalent estimates for the entire Western US. It has already caught the attention of local and regional water managers.

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Earth Day: 7 ways �山�� researchers are driving change

Anonymous — Thu, 17 Apr 2025 18:00:00 +0000

Earth Day: 7 ways �山�� researchers are driving change Anonymous (not verified) Thu, 04/17/2025 - 12:00

The theme of Earth Day 2025 is “Our Power, Our Planet.” �山�� researchers explore ways to pioneer new approaches to clean energy and much, much more. They crunch expansive datasets to provide the world with the best possible knowledge and research on the impacts of a changing climate. They develop technologies to reduce emissions and slow the rate of climate change.

Learn about some of �山��'s exciting research projects as you ponder the importance of Earth Day this year.

Editor's note: A version of this article was originally published in April 2024. It has been updated with new research in climate change and sustainability.

As AI explosion threatens progress on climate change, these researchers are seeking solutions

�山�� engineers are exploring novel energy storage options and pinning down the best locations for future data centers to lower their climate impact.

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Climate & Environment

A vicious cycle: How methane emissions from warming wetlands could exacerbate climate change

A vicious cycle

Our hope is that by rapidly reducing emissions, we can avoid triggering more severe and abrupt climate feedback that could lead to catastrophic events.

Methane sponges

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Our hope is that by rapidly reducing emissions, we can avoid triggering more severe and abrupt climate feedback that could lead to catastrophic events.

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