Research shows rivers release ancient carbon dioxide into the atmosphere, uncovering a greater role for plants and soil in the carbon cycle

University of Bristol

Facebook

WeChat
WhatsAppEmail

 

image: 

Aerial image of rivers in northeast Siberia which are known to emit old carbon.

view more 

Credit: University of Bristol

A new study has revealed for the first time that ancient carbon, stored in landscapes for thousands of years or more, can find its way back to the atmosphere as CO₂ released from the surfaces of rivers.

The findings, led by scientists at the University of Bristol and the cover story of the journal Nature, mean plants and shallow soil layers are likely removing around one gigatonne more CO₂ each year from the atmosphere to counteract this, emphasising their pivotal and greater part in combating climate change.

Lead author Dr Josh Dean, Associate Professor in Biogeochemistry and UKRI Future Leaders Fellow at the University of Bristol, said: “The results took us by surprise because it turns out that old carbon stores are leaking out much more into the atmosphere then previous estimates suggested.

“The implications are potentially huge for our understanding of global carbon emissions. Plants and trees take up CO2 from the atmosphere and can then lock this carbon away in soils for thousands of years.

“Our findings show some of this old carbon, as well as ancient carbon from rocks, is leaking sideways into rivers and making its way back to the atmosphere. We don’t yet know how humans are affecting this flow of ancient carbon, but we do know plants and trees must be taking up more carbon from the atmosphere today to account for this unrecognised release of old carbon.”

Rivers transport and release methane and carbon dioxide as part of the global carbon cycle. Until now, scientists believed the majority of this was a quick turnover derived from the recycling of recent plant growth – organic material broken down and carried into the river system in the past 70 years or so. This new study indicates the opposite, with more than half – some 60% – of emissions being attributed to long-term carbon stores accumulated over hundreds to thousands of years ago, or even longer.

The international research team, led by scientists at the University of Bristol, University of Oxford and the UK Centre for Ecology and Hydrology, studied more than 700 river reaches from 26 different countries across the world.

They took detailed radiocarbon measurements of carbon dioxide and methane from the rivers. By comparing the levels of carbon-14 in the river samples with a standard reference for modern atmospheric CO2, the team was able to date the river carbon.

Co-author Prof Bob Hilton, Professor of Sedimentary Geography at the University of Oxford, explained: “We discovered that around half of the emissions are young, while the other half are much older, released from deep soil layers and rock weathering that were formed thousands and even millions of years ago.”

The research was supported by funding from UK Research and Innovation (UKRI) Natural Environment Research Council (NERC).

Co-author Dr Gemma Coxon, Associate Professor in Hydrology and UKRI Future Leaders Fellow at the University of Bristol, said: “Rivers globally release about two gigatonnes of carbon each year, compared to human activity that results in between 10-15 gigatonnes of carbon emissions. These river emissions are significant at a global scale, and we’re showing that over half of these emissions may be coming from carbon stores we considered relatively stable. This means we need to re-evaluate these crucial parts of the global carbon cycle.”

Further building on these findings, the researchers plan to explore how the age of river carbon emissions varies across rivers the study was not able to capture, as well as investigating how the age of these emissions may have changed through time. 

Paper

‘Old carbon routed from land to the atmosphere by global river systems’ by Joshua F. Dean et al in Nature

---

Journal

Nature

Image depicts the global carbon cycle with trees and plants absorbing CO₂ and it being released back into the atmosphere from rivers via deep and shallow soil layers.  

Credit

University of Bristol / sciencegraphicdesign.com

Image shows the research as the cover story of Nature.

Credit

Nature

DOI

10.1038/s41586-025-09023-w 

Subject of Research

Not applicable

Article Title

‘Old carbon routed from land to the atmosphere by global river systems’

Article Publication Date

4-Jun-2025

 

Six decades of data on North Atlantic phytoplankton reveal that their biomass has decreased up to 2% annually across most of the Atlantic Ocean, with potentially widespread implications for the wider food web under climate change

PLOS

Facebook

XLinkedInWeChatBluesky
Email

 

image: 

Six decades of data on North Atlantic phytoplankton reveal that their biomass has decreased up to 2% annually across most of the Atlantic Ocean.

view more 

Credit: Ekaterina Boltaga, Unsplash, CC0 (https://creativecommons.org/publicdomain/zero/1.0/)

Six decades of data on North Atlantic phytoplankton reveal that their biomass has decreased up to 2% annually across most of the Atlantic Ocean, with potentially widespread implications for the wider food web under climate change

Article URL: https://plos.io/4kq8QEt

Article title: Large, regionally variable shifts in diatom and dinoflagellate biomass in the North Atlantic over six decades

Author countries: Canada

Funding: This work was supported by grants from the Simons Foundation (549935 to AJI, 549937 and 986772 to ZVF), the Ocean Frontier Institute (NWABCP to AJI and ZVF), and Discovery grant awards from the National Science and Engineering Research Council of Canada (AJI, ZVF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

---

Journal

PLOS One

DOI

10.1371/journal.pone.0323675 

Article Title

Large, regionally variable shifts in diatom and dinoflagellate biomass in the North Atlantic over six decades

Article Publication Date

4-Jun-2025

 

The Great Lakes are in an extreme new era

Heat waves and cold spells are now more common on the Great Lakes, according to U-M research, with implications for the region's weather, economy and ecology

University of Michigan

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

The frequency and intensity of heatwaves and cold spells in the Great Lakes, seen as spikes in these graphs, entered a new regime in the 1990s, according to new research led by the University of Michigan. Using a measurement called degree days that combines the magnitude and duration of a temperature anomaly, the researchers showed the median value more than doubled following a "phase shift" shown as a red line (similar plots are available for all of the Great Lakes).

view more 

Credit: Adapted with permission from Abdelhady, H.U., et al. Commun Earth Environ, 2025, DOI: 10.1038/s43247-025-02341-x (Used under a CC BY 4.0 license)

Heat waves and cold spells are part of life on the Great Lakes. But new research from the University of Michigan shows that is true today in a fundamentally different way than it was even 30 years ago.

"The appearance of these extreme temperatures is increasing," said Hazem Abdelhady, a postdoctoral research fellow in the U-M School for Environment and Sustainability, or SEAS. "For most lakes, the appearance is up more than 100% compared with before 1998." That timing is significant because it coincides with the 1997-1998 El Niño, which is one of the strongest on record, he added.

To reveal this trend, Abdelhady and his colleagues developed a state-of-the-art approach to modeling the surface temperature of the Great Lakes, which allowed them to study heat waves and cold spells dating back to 1940. The surface water temperature of the Great Lakes plays an important role in the weather, which is an obvious concern for residents, travelers and shipping companies in the region.But the uptick in extreme temperature events could also disrupt ecosystems and economies supported by the lakes in more subtle ways, Abdelhady said.

"These types of events can have huge impacts on the fishing industry, which is a billion-dollar industry, for example," Abdelhady said. Tribal, recreational and commercial fishing in the Great Lakes account for a total value of more than $7 billion annually, according to the Great Lakes Fishery Commission.

While fish can swim to cooler or warmer waters to tolerate gradual temperature changes, the same isn't always true for sudden jumps in either direction, Abdelhady said. Fish eggs are particularly susceptible to abnormal temperature spikes or drops.

Hot and cold streaks can also disrupt the natural mixing and stratifying cycles of the lakes, which affects the health and water quality of lakes that people rely on for recreation and drinking water.

Now that the researchers have revealed these trends on each of the Great Lakes, they're working to build on that to predict future extreme temperature events as the average temperature of the lakes—and planet—continue to warm. In studying those events and their connections with global climate phenomena, such as El Niños and La Niñas, we can better prepare to brace for their impact, Abdelhady said.

"If we can understand these events, we can start thinking about how to protect against them," Abdelahdy said.

The study was conducted through the Cooperative Institute for Great Lakes Research, or CIGLR, and published in Communications Earth & Environment, part of the Nature journal family. The work was supported by the National Science Foundation, its Global Centers program and the National Oceanic and Atmospheric Administration, or NOAA.

Capturing the greatness of the lakes

One of the challenges of this work was the size of the problem itself. Although researchers have developed computer models that can simulate processes in most lakes around the world, the Great Lakes aren't most lakes. 

For starters, they're an interconnected system of five lakes. They also contain more than a fifth of the world's fresh surface water. And the length of their shoreline is comparable to that of the U.S.'s entire Atlantic coast—including the gulf states.

In many regards, the Great Lakes have more in common with coastal oceans than with other lakes, said study coauthor Ayumi Fujisaki-Manome, who is an associate research scientist with SEAS and CIGLR.

"We can't use the traditional, simpler models for the Great Lakes because they really don't do well," Fujisaki-Manome said.

So Abdelhady turned to modeling approaches used to study coastal oceans and tailored them for the Great Lakes. But there was also a data hurdle to overcome in addition to the modeling challenges.

Satellites have enabled routine direct observations of the Great Lakes starting about 45 years ago, Fujisaki-Manome said. But when talking about climate trends and epochs, researchers need to work with longer time periods.

"The great thing with this study is we were able to extend that historical period by almost double," Fujisaki-Manome said.

By working with available observational data and trusted data from global climate simulations, Abdelhady could model Great Lakes temperature data and validate it with confidence back to 1940.

"That's why we use modeling a lot of the time. We want to know about the past or the future or a point in space we can't necessarily get to," said coauthor Drew Groneworld, an associate professor in SEAS and a leader of the Global Center for Climate Change and Transboundary Waters. "With the Great Lakes, we have all three of those."

David Cannon, an assistant research scientist with CIGRL, and Jia Wang, a climatologist and oceanographer with NOAA's Great Lakes Environmental Research Laboratory, also contributed to the study. The study is a perfect example of how collaborations between universities and government science agencies can create a flow of knowledge that benefits the public and the broader research community, Gronewold said.

The team's model is now available for other research groups studying the Great Lakes to explore their questions. For the team at U-M, its next steps are using the model to explore spatial differences across smaller areas of the Great Lakes and using the model to look forward in time.

"I'm very curious if we can anticipate the next big shift or the next big tipping point," Gronewold said. "We didn't anticipate the last one. Nobody predicted that, in 1997, there was going to be a warm-winter El Niño that changed everything."

Red boxes show the intensity of heat waves, while blue boxes show the intensity of cold spells on Lake Superior, the fastest warming of the Great Lakes, since 1940. Black lines indicate "breakpoints" or significant shifts in trends (similar plots are available for all of the Great Lakes).

Credit

Adapted with permission from Abdelhady, H.U., et al. Commun. Earth Environ., 2025, DOI: 10.1038/s43247-025-02341-x

Journal

Communications Earth & Environment

DOI

10.1038/s43247-025-02341-x 

Article Title

Climate change-induced amplification of extreme temperatures in large lakes

 

The atmosphere’s growing thirst is making droughts worse, even where it rains

Increasing atmospheric evaporative demand outpaces rising precipitation rates due to warming

University of California - Santa Barbara

LinkedInWeChatBlueskyMessageWhatsAppEmail

(Santa Barbara, Calif.) — Hot air holds more moisture. That’s why you can blow your hair dry even after a steamy shower. It’s also what dumps rain in the tropics and sucks water from desert soils.

A new study, published in Nature, shows that the atmosphere’s growing thirst for water is making droughts more severe, even in places where rainfall has stayed the same. The paper details how this “thirst” has made droughts 40% more severe across the globe over the course of the past 40 years.

“Drought is based on the difference between water supply (from precipitation) and atmospheric water demand. Including the latter reveals substantial increases in drought as the atmosphere warms,” said co-author Chris Funk, director of the Climate Hazards Center at UC Santa Barbara.

The hidden force behind worsening droughts

Droughts are usually blamed on a dearth of rain. But scientists have discovered another factor at work: warming air is increasing the atmosphere’s evaporative demand. Atmospheric evaporative demand (AED) acts like a sponge, soaking up moisture faster than it can be replaced. This can pull more water out of soils, rivers and plants.

It’s not clear whether a warmer atmosphere will make droughts more or less intense, frequent and widespread. “As the atmosphere warms, air at a constant relative humidity will hold more water vapor, so rainfall may increase,” Funk explained. “But at the same time, atmospheric evaporative demand is also expected to increase. So which is increasing more quickly?”

Funk joined an international team of scientists to examine the role AED is playing in exacerbating droughts around the world.

A new way to measure drought’s growing danger

Scientists knew AED was important, but few studies had carefully measured its global impact using real-world observations, making it harder to predict and prepare for droughts. This new study used a set of high-resolution data covering more than a century, and applied advanced methods to track how AED has increased and how much worse it has made droughts.

“We face a big challenge,” explained lead author Solomon Gebrechorkos, a hydro-climatologist at University of Oxford. “There’s no direct way to measure how ‘thirsty’ the atmosphere is over time. So, we used high-resolution climate data, identified through a comprehensive global evaluation, and applied the most advanced models for atmospheric evaporative demand — models that account for multiple climate variables, not just temperature.”

The team compared water supply, based on precipitation, and atmospheric evaporative demand using multiple world-class datasets. They then looked at changes in the standardized data, evaluating these changes over time. “This allowed us to compare wet and dry regions using a common framework,” Funk explained. The authors then identified statistically significant increases in drought.

They found that AED has increased faster than precipitation rates, suggesting an alarming tendency towards drier conditions. “I find these results very concerning, but perhaps not terribly surprising,” Funk said. “Most of us are familiar with how air temperatures are increasing rapidly, but most people may not realize the connections between this warming and the desiccating influence of the atmosphere.” In warm areas, raising the temperature by just a couple degrees can dramatically increase the atmosphere's ability to draw moisture from crops, rangelands and forests, he added.

Understanding drought in a warming world

This study reinforces past work showing that droughts will become more intense in a warming world. This has implications for global food and water security, which may in turn amplify political instability and conflict. Easier to see are more direct links between increased AED and wildfire. A thirsty atmosphere desiccates plants, which contributes to larger wildfires.

Looking into the future, this study underscores the importance of early warning systems, drought risk management and effective anticipatory actions. Predicting droughts, and increased atmospheric demand, can trigger effective interventions. For example, farmers might use micro-irrigation or water-retentive soil treatments to offset increased AED. “To counter increasing drought trends, we need to anticipate and manage the extreme events that lead to concerning increases in drought risk,” Funk said. 

Researchers are also interested in uncovering how evaporation and atmospheric demand interact with water supplies, not just rainfall patterns. Scientists will need to study how farmers, cities and ecosystems can adapt to a world where the atmosphere constantly demands more moisture.

---

Journal

Nature

 

Syntato awarded ARIA funding to advance chromosome engineering in crops

Medical Research Council (MRC) Laboratory of Medical Sciences

XLinkedInWeChatBlueskyMessageWhatsAppEmail

Syntato originated from the Synthetic Biology laboratory at the LMS, embedded within the Hammersmith Campus at Imperial College London, led by Dr Karen Sarkisyan, an expert in bioengineering with a track record in translating emerging genetic technologies into real-life products. Karen previously co-founded Light Bio, which successfully commercialised the world’s first glow-in-the-dark ornamental plant and gained global attention, with its product Firefly Petunia featured in numerous global media outlets, as well as on the cover of TIME magazine. 

Syntato’s project is one of several initiatives funded by ARIA’s Synthetic Plants Program, launched to catalyse a new generation of major crops that are more productive, resilient and sustainable. Syntato will focus on reducing the cost and iteration time of chromosome engineering by making chromosomes modular and reusable. The project is a joint effort with a Valencian biotechnology company Madeinplant, co-founded by synthetic biologists Dr Diego Orzaez and Dr Marta Vázquez Vilar, and the London Biofoundry, led by Dr Marko Storch. The collaboration enables all sides to combine expertise and technologies to achieve the ambitious goal of building a synthetic chromosome and using it to create a new potato variety in three years. 

Chromosome-scale engineering is becoming the enabling infrastructure of plant biotechnology—much as chip fabrication underpins modern electronics—because it allows entire suites of adaptive crop traits to be built and deployed as a single, modular unit. Custom-designed chromosomes leave the native genome intact, yet deliver system-level improvements in one step, turning future crop development from incremental gene edits into rapid, scalable platform design. 

“Chromosome-scale engineering is an essential technology to master if we are serious about creating crops that are adaptive to climate changes, more productive and able to resist pests and diseases without any sprayed chemicals. ARIA’s backing, together with the continued support of translational work from the LMS, allows us to realistically approach this challenge,” says Karen.  

The project centers around automation of plant cell culture work, facilitating high-throughput assessment of chromosome design prototypes. To enable this work, Syntato has partnered with Briefly.Bio, a provider of a unique AI-powered interface for lab automation. The long-term contract with Briefly will allow Syntato’s scientists to modularly configure their robotic pipeline, quickly and independently. 

Located at the heart of Imperial College London’s ecosystem for synthetic biology startups, Syntato is establishing a partnership with the Bezos Centre for Sustainable Protein to explore food-related applications of this new technology platform.