The perception of how the land surface releases carbon dioxide (CO2) typically conjures up images of large-scale deforestation or farmers churning up the soil.
However, there is an intriguing – and underappreciated – role played by the world’s rivers.
Right now, plants and soils absorb about one-third of the CO2 released by human activity, similar to how much the oceans take up.
Over thousands to millions of years, some of this land-fixed carbon can end up being buried in sediments, where it eventually forms rocks.
The waters that feed rivers flow through plants, soils and rocks in landscapes, picking up and releasing carbon as they go.
This process is generally considered to be a sideways “leakage” of the carbon that is being taken up by recent plant growth.
However, the age of this carbon – how long it resided in plants and soils before it made it into rivers and then to the atmosphere – has remained a mystery.
If the carbon being released by rivers is young, then it can be considered a component of relatively quick carbon cycling.
However, if the carbon is old, then it is coming from landscape carbon stores that we thought were stable – and, therefore, represents a way these old carbon stores can be destabilised.
In our new study, published in Nature, we show that almost 60% of the carbon being released to the atmosphere by rivers is from these older sources.
In total, this means the world’s rivers emit more than 7bn tonnes of CO2 to the atmosphere each year – more than the annual fossil-fuel emissions from North America.
This means that there is a significant leak of carbon from old stores that we thought were safely locked away.
Previous work has shown that local land-use change, such as deforestation and climate-driven permafrost thaw, will directly release old carbon into rivers. Whether this is happening at the global scale remains a significant unknown for now.
Who are you calling old?
How do you tell how old carbon is? We employ the same technique that is used to determine the age of an archaeological relic or to verify the age of a vintage wine – that is, radiocarbon dating.
Radiocarbon is the radioactive isotope of carbon, which decays at a known rate. This enables us to determine the age of carbon-based materials dating back to a maximum age of about 60,000 years old.
We know that some of the carbon that rivers release is very young, a product of recent CO2 uptake by plants.
We also know that rivers can receive carbon from much older sources, such as the decomposition of deep soils by microbes and soil organisms or the weathering and erosion of ancient carbon in rocks.
Soil decomposition can release carbon ranging from a few years to tens of thousands of years. An example of very old soil carbon release is from thawing permafrost.
Rock weathering and erosion releases carbon that is millions of years old. This is sometimes referred to as “radiocarbon-dead” because it is so old all the radiocarbon has decayed.
Rivers are emitting old carbon
In our new study, we compile new and existing radiocarbon dates of the CO2 emissions from around 700 stretches of river around the world.
We find that almost 60% of the carbon being released to the atmosphere by rivers is from older sources (hundreds to thousands of years old, or older), such as old soil and ancient rock carbon.
In the figure below, we suggest how different processes taking place within a landscape can release carbon of different ages into rivers, driving its direct emission to the atmosphere.
So, while rivers are leaking some modern carbon from plants and soils as part of the landscape processes that remove CO2 from the atmosphere, rivers are also leaking carbon from much older landscape carbon stores.
One major implication of this finding is that modern plants and soils are leaking less carbon back to the atmosphere than previously thought, making them more important for mitigating human-caused climate change.
We find that the proportion of old carbon contributing to river emissions varies across different ecosystems and the underlying geology of the landscapes they drain.
In the figure below, we show that landscapes underlain by sedimentary rocks, which are the most likely to contain substantial ancient (or “petrogenic”) carbon, also had the oldest river emissions. We also show that the type of ecosystem (biome) was also important, although the patterns were less clear.
What is obvious is that at least some old carbon was common across most of the rivers we observed, regardless of size and location.
We provide evidence that there is a geological control on river emissions. And the variability in the ecosystem also indicates important controlling factors, such as soil characteristics, vegetation type and climate – especially rainfall patterns and temperature which are known to impact the rate of carbon release from soils and rock weathering.
Are old carbon stores stable?
Long-term carbon storage in soils and rocks is an important process regulating global climate.
For example, the UK’s peatlands are important for regulating climate because they can store carbon for thousands of years. That is why restoring peatlands is such a great climate solution.
Rivers emit more than 7bn tonnes of CO2 to the atmosphere each year – that’s equivalent to about 10-20% of the global emissions from fossil fuel burning annually.
If 60% of river carbon emissions are coming from old carbon stores, then this constitutes a significant leak of carbon from old stores we thought were safely locked away.
Another major implication of our study is that these old carbon stores can be mobilised and routed directly to the atmosphere by rivers, which would exacerbate climate change if these stores are further destabilised.
As can be seen in the figure below, we found that river carbon emissions appeared to be getting older since measurements first began in the 1990s (lower F14Catm means older radiocarbon ages).
We found that river carbon emissions appeared to be getting older since measurements first began in the 1990s.
While there are several caveats to interpreting this trend, it is a warning sign that human activities, especially climate change, could intensify the release of carbon to the atmosphere via rivers.
Given the strong link between soil carbon and river emissions, if this trend is a sign of human activity disturbing the global carbon cycle, it is likely due to landscape disturbance mobilising soil carbon.
Using rivers to monitor global soil carbon storage
Rivers collect waters from across the landscapes they flow through and therefore provide a tool to track processes happening out of sight.
A drop of water landing in a landscape travels through soils and rock before reaching the river, and its chemistry, including its radiocarbon age, reflects the processes occurring within the landscape.
Monitoring the age of carbon in rivers can therefore tell you a lot about whether their landscapes are storing or releasing carbon.
This has been shown to help identify carbon loss in degraded tropical peatlands, thawing Arctic permafrost and due to deforestation.
River radiocarbon is sensitive to environmental change and could therefore be a powerful monitoring tool for detecting the onset of climate tipping points or the success of landscape restoration projects, for example.
While we present data spread out across the world, there are quite a few gaps for important regions, notably where glacier change is happening and others where droughts and flood frequencies are changing.
These include areas with low amounts of data in Greenland, the African continent, the Arctic and Boreal zones, the Middle East, eastern Europe, western Russia, Central Asia, Australasia and South America outside of the Amazon.
All these regions have the potential to store carbon in the long-term and we do not yet know if these carbon stores are stable or not under present and future climate change.
River radiocarbon offers a powerful method to keep tabs on the health of global ecosystems both now and into the future.
The post Guest post: How the world’s rivers are releasing billions of tonnes of ‘ancient’ carbon appeared first on Carbon Brief.
Guest post: How the world’s rivers are releasing billions of tonnes of ‘ancient’ carbon
Marcelo Behar is the COP30 Special Envoy for Bioeconomy and co-founder of Ambition Loop Brazil.
Can we be the generation to end the rampant deforestation that is harming the planet’s ecosystems and climate? Back in February, the Brazilian COP30 Presidency opened a call for submissions on its proposed Roadmap for Halting Deforestation and Forest Degradation, which closes today.
What might look like a technical step quickly drew significant attention, with more than 100 responses submitted by governments, civil society organisations, businesses and other stakeholders.
This level of engagement is telling. It reflects both the urgency of the issue and the recognition that this process could shape whether the global goal to end deforestation by 2030 finally moves from ambition to delivery.
As a Brazilian, I see this moment with both pride and realism. Brazil has played a central role in elevating forests on the climate agenda, and the COP30 Presidency has shown leadership in carrying this issue forward far beyond the Belém summit.
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But last year also offered a sobering signal. Despite strong efforts from the Brazilian Presidency, the proposed roadmap did not secure consensus in the final outcome of COP30. That outcome underlined a simple truth: while there is broad recognition of the importance of forests, agreeing on how to move forward remains complex. The road ahead is still long and likely uneven.
That is precisely why this moment matters.
Progress on commitments falling short
The world is not short of commitments. Over the past decade, countries have repeatedly pledged to halt and reverse deforestation by 2030. There is a growing body of experience through the REDD+ (Reducing Emissions from Deforestation and Degradation) programme, including the emergence of jurisdictional approaches that are beginning to connect forest protection with finance at scale.
Initiatives such as the Forest and Climate Leaders’ Partnership have helped sustain political attention and cooperation among countries, while national strategies continue to evolve, and Indigenous Peoples and local communities remain at the forefront of protecting forests.
And yet, progress is still falling short.
The gap is not only one of alignment. It is also one of political will – and of having a credible, shared pathway that brings together these efforts in a way that drives implementation at scale.
Civil society is watching this process closely. For many organisations working across climate, nature and conservation, this is not just another initiative – it is a priority. After years of advocating to end deforestation, there is a strong sense that this moment cannot be lost. The expectation is clear: this roadmap must move beyond intention and help unlock real progress.
The opportunity now is to ensure that it does exactly that. This cannot become another report.
Implementation key to roadmap success
A detailed assessment of pathways and challenges, however valuable, will not be enough to change outcomes on the ground. What is needed is an implementation roadmap, one that connects existing commitments, aligns incentives and provides clarity on how to move from ambition to delivery between now and 2030.
The consultation process is an important step. But its value will ultimately be judged by what it produces.
If the roadmap is to succeed, several priorities should guide its development.
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First: policy. It must be designed as a tool for implementation. That means going beyond diagnosis to define concrete action: who needs to act, by when, and how progress will be tracked. The solutions are not new, but coordination has been missing.
Second: accountability. It should bring coherence to the existing landscape. The value of a roadmap lies not in creating new commitments, but in connecting what already exists: global targets, REDD+ experience, national action plans, Indigenous leadership and supply chain initiatives. Reducing fragmentation is essential to accelerating delivery.
Early milestones needed
Third: finance. It must be grounded in economic reality. Halting deforestation will not happen without addressing the incentives that underpin it. Aligning public finance, private investment, and market demand with forest protection is not a technical detail; it is the core of the transition.
Fourth: transparency. Legitimacy will depend on openness. A credible roadmap cannot be developed behind closed doors. Governments, Indigenous Peoples and local communities, civil society, business and finance actors all have a role to play and must be able to see how their contributions shape the outcome.
Fifth: urgency. Progress must be visible in 2026. Without early milestones, momentum will fade. By the time climate negotiators gather in Bonn mid-year, the roadmap should have a clear structure, priority actions and growing political backing.
Governments must deliver on the plan
Finally, countries themselves will need to step forward. Last year’s outcome showed that support alone is not enough. Delivering this roadmap will require active political engagement. That means governments that are willing not only to participate in the process, but to help shape and implement it.
Brazil has created an important opening. It has also taken on the responsibility that comes with leadership: to help turn a widely supported idea into something that can deliver in practice.
The commitment to end deforestation by 2030 already exists. What is still needed is a path. And the courage to walk it.
The post How a Brazil-led roadmap can rescue global pledge to halt deforestation appeared first on Climate Home News.
How a Brazil-led roadmap can rescue global pledge to halt deforestation
A US biofuels producer that exports “green” aviation fuel to Britain and the European Union has purchased beef tallow from a Brazilian supply chain tied to illegal deforestation in the Amazon, shipping data and a court document show.
Diamond Green Diesel (DGD), a major provider of sustainable aviation fuel (SAF) and renewable diesel, has sourced hundreds of thousands of tonnes of beef tallow from Brazil, alongside waste fats from other sources, over the last three years, as global demand for biofuel feedstocks soars.
Reporting by Unearthed and nonprofit investigative outlet Repórter Brasil reveals DGD’s connection to a rendering plant that has sourced supplies from a meatpacker fined for buying cattle from an illegally deforested Amazon reserve. A previous investigation by Reuters and Repórter Brasil found DGD had bought animal fat from two other rendering factories linked to supplies of cattle from illegal ranches.
The newly identified factory, Pacífico Indústria e Comércio de Óleos e Proteínas Ltda, which is based in Cacoal, a small city in the far-western Amazon state of Rondônia, has been supplied by Rondônia meatpacker DistriBoi, a 2022 court document shows.
DistriBoi was fined two years ago for illegally purchasing cattle from the state’s Jaci-Paraná conservation reserve, which has been ravaged by illegal ranching.
There is no suggestion that the companies involved were aware of deforestation at farm level. But the findings suggest a traceability gap in the supply chain of feedstocks for sustainable fuels, where cattle by-products are subject to less oversight than the primary commodities of the cattle industry, such as meat and leather.
Pristine rainforest blanketed the Jaci-Paraná reserve when it was created 30 years ago to protect traditional forest activities such as rubber tapping and nut harvesting.
Today, illegal ranching has devoured nearly 80% of its forest cover and it has become a notorious example of the devastation wrought by land grabbers in the world’s largest rainforest.
“The damage to biodiversity has been devastating,” said local Indigenous activist Neidinha Suruí, who featured in the 2025 Emmy Award-winning documentary “O Território”.
“It is sad to see what has been lost,” she said.
Greener air travel?
The “renewable diesel” and sustainable aviation fuel (SAF) that are being exported by DGD – a joint venture between US oil refiner Valero Energy Corp and Texas-based Darling Ingredients – are classed as “green” because they are made from feedstocks classified as waste, including tallow, which consists of fat separated from cattle carcasses.
Many governments and airlines are pinning their hopes for greener flying on SAF made with organic waste materials, including Britain which introduced a compulsory blending requirement last year.
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Air travel accounts for about 2.5% of global carbon emissions and in contrast to other transport sectors that can be electrified, shrinking aviation’s carbon footprint is much more difficult.
Waste products such as beef tallow and used cooking oil (UCO) are considered the greenest of viable SAF feedstocks on the grounds that they do not create competition with foodstuffs such as soy oil or palm oil, nor increase deforestation pressure.
But there is concern that the global rush to ramp up SAF use could indirectly exacerbate deforestation pressure by increasing demand for feedstocks such as tallow and UCO.
That could increase the profit margins of cattle ranches – including illegal ones – and have other unintended consequences, such as encouraging fraud in supply chains, as Climate Home News has reported.
An investigation published in March by Climate Home News and Swedish broadcaster SVT found that Finnish biofuels giant Neste is sourcing key ingredients for its SAF from an opaque supply chain that enables fresh palm oil to be passed off as used, waste oil.
Because tallow is classified as waste by regulators in markets including the UK and EU, the green fuel industry’s most widely used certification scheme – International Sustainability and Carbon Certification (ISCC) – does not assess whether forests were cleared to rear the cattle that produced it in the first place.
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This allows tallow from cattle to qualify as a sustainable feedstock for green fuels, even if they were raised on illegally deforested land.
“There is clearly an oversight within the rules if the products, in this case animal tallow, are originally coming from deforested land,” said Cian Delaney, a campaign coordinator at the clean transport and energy advocacy group Transport & Environment.
That means government SAF mandates aimed at stemming air travel emissions could help boost the earnings of cattle ranchers linked to illegal deforestation in Brazil, where ranching and other forms of agriculture have been the main driver of forest loss.
Land grabbers clear way for ranchers
Once covered by an unbroken rainforest canopy, Rondônia’s Jaci-Paraná reserve has been decimated by illegal deforestation driven by cattle ranching – a major cause of tree loss in the Amazon.
Land-grabbers have seized – often violently – and cleared more than three-quarters of its forest for pasture, as ranching has steadily advanced into the southern Amazon.
Suruí, the local Indigenous activist, said companies that buy products derived from illegal activities perpetuate environmental crimes in the rainforest.
“If there were no meat processors buying illegally sourced cattle, there would be no land grabbing and no deforestation,” Suruí told Repórter Brasil, which partnered on the new investigation with Unearthed, and a team of journalists supported by JournalismFund Europe.
Lawsuits and linked supply chains
Brazilian President Luiz Inácio Lula da Silva has pledged to end all deforestation in the country by 2030, in part by strengthening environmental enforcement in the world’s biggest rainforest.
In Rondônia, authorities have launched more than 50 lawsuits related to land-grabbing and deforestation in the Jaci-Paraná reserve alone. Local slaughterhouse DistriBoi is named in 31 of the lawsuits, including the 2024 case in which it was fined.
According to the 2022 court document, which concerned an unrelated labour dispute, lawyers for Pacífico refer to DistriBoi as the rendering plant’s “largest supplier of raw materials”.
US-based DGD received almost 15,000 tonnes of tallow from Pacífico from 2023 to 2025 at its Texas refinery, as well as used cooking oil from various countries and sources, according to trade database Panjiva.
Darling Ingredients is also a parent company of Pacífico since its 2022 acquisition of Brazilian rendering company FASA Group.
A spokesperson for Darling Ingredients denied that Pacífico had sourced beef residues from DistriBoi’s Ji-Paraná slaughterhouse – one of two that the meatpacker operates in Rondônia.
“The rendering plant Pacífico does not source any materials from the slaughterhouse Distriboi in Ji-Paraná,” the spokesperson said in an emailed response, without providing evidence or commenting directly on the content of the 2022 court document.
Darling did not respond to a follow-up question about Distriboi’s other slaughterhouse in the region, which, according to cattle transfer documents, has also bought from a farm that has illegally cleared forest within the extractive reserve.
“Our relationships are typically with the slaughterhouse, several levels removed from cattle ranchers. Regardless, we are committed to ensuring our raw materials are deforestation free. We expect our raw material suppliers to abide by our supplier code of conduct. In addition, we are in the process of requiring all [the] raw materials to attest that their material is deforestation free,” the spokesperson said in a statement.
DistriBoi said in an apparent reference to the pending Jaci-Paraná lawsuits that “the matters mentioned … are already under review, including by higher courts”. It has previously denied wrongdoing. The company’s statement did not address a question about its commercial ties to Pacífico.
Valero Energy, the major refiner that co-owns DGD with Darling Ingredients, did not respond to requests for comment, nor did DGD itself.
From slaughterhouse to SAF
In an effort to rein in carbon emissions from air travel, regulators in Britain and the EU have mandated progressively increasing SAF blending quotas in the years ahead, creating a new market for feedstocks including beef tallow.
Brazil’s exports of tallow to the US have risen sharply in recent years, up from less than 10,000 tonnes in 2021 to almost 400,000 tonnes last year, according to Panjiva, reflecting growing demand for biofuels like SAF.
In the UK, Europe’s biggest aviation market by seat capacity, jet fuel was required to contain 2% SAF by the end of 2025, rising to 10% by 2030 and 22% by 2040.
DGD shipped 134,000 tonnes of SAF worth nearly $90 million from Texas to the UK in 2025, according to trade data from Panjiva. The company also exported smaller amounts of renewable diesel to Britain.
The EU received biofuels, including small quantities of SAF, worth over $1.1 billion from DGD’s Texas refinery last year, figures show.
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Unearthed’s investigation could not identify which airlines or airports buy DGD’s SAF once it arrives in Britain.
Valero, DGD’s other parent company, is positioning itself as a key player in the transition to lower-carbon fuels in the UK, where it markets its renewable diesel under the Texaco brand.
It has been an active participant in SAF policy discussions and has criticised the government’s planned cap on waste fat sources in SAF, calling them “the world’s most cost-effective production route for SAF” in a submission to parliament.
Helping to cut emissions?
Even tighter oversight over SAF feedstocks is crucial to ensure that blending mandates such as Britain’s are effectively lowering emissions, said Anna Krajinska, a director at Transport & Environment UK.
Forests store vast amounts of carbon; when they are cut down or burned this carbon is released into the atmosphere.
“If there’s tallow coming from land that’s been deforested, then those emissions might be so high that you might not be getting to the greenhouse gas reduction threshold,” Krajinska said.
But as the world’s appetite for flying keeps on growing, some experts say SAF is the only viable means to reduce aviation emissions at present.
Referring to the deforestation links identified in Unearthed’s investigation, Wouter Dewulf, an aviation economist at Belgium’s University of Antwerp, said it “would be important to assess how large this infraction is”.
“I’m quite sure you have aberrations,” Dewulf added. “But biofuels are the best alternative for the moment.”
T&E’s Delaney said there needs to be less opacity and better oversight from regulatory authorities. “Right now, there are just too many blindspots,” he added.
The post UK imports of “green” jet fuel linked to Amazon deforestation appeared first on Climate Home News.
UK imports of “green” jet fuel linked to Amazon deforestation
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