The degradation of trees at the edges of tropical forests is more widespread than previously thought, according to new research.
The study, published in Nature, explains that trees near deforested or degraded areas of the forest are more vulnerable to drought, as well as to human activity such as logging. These “edge effects” are measurable up to 1.5km into the forest, the authors find.
This is an “amazing result”, a study author tells Carbon Brief, because previous studies detected these effects only within the first 120 metres of the forest edge. The new figure indicates that 18% of the remaining tropical moist forests are impacted by edge effects – an area more than 200% larger than previously estimated.
Experts not involved in the study tell Carbon Brief that quantifying tropical forest degradation is “frustratingly elusive”. And while some praise the methods used in the paper, others advise caution when interpreting the conclusions.
Two Brazilian scientists also tell Carbon Brief that the study overlooks important work from institutions in the global south who are also working on this problem. They advise that scientists from local groups should be invited to contribute to research in this area.
Forest height
Tropical forests account for around 45% of forest cover globally. These forests are well-known for their high biodiversity and the crucial ecosystem services that they provide. They also hold around one-quarter of all land-based carbon.
The new study assesses how deforestation and degradation affect “moist tropical forests” – tropical forests in the equatorial belt with a fairly consistent annual temperature and high levels of rainfall. Tropical dry forests and deciduous forests are not included in the analysis.
Research shows that around 17% of tropical moist forests disappeared over 1990-2021, largely due to human activity such as logging and fires. Of the 1,071m hectares that remained globally in 2019, around 10% were degraded, the new study says. This means that they suffered human-induced “disturbances” that led to a partial loss of their tree cover or function.
Furthermore, trees at the edges of tropical forests have higher mortality rates than trees in the centre, because they are more exposed to disturbances such as fire and drought. When intact forest landscapes become fragmented – for example, due to logging, fire, drought or the construction of roads into the forest – these “edge effects” can lead to further forest degradation.
The authors use data collected by the Global Ecosystem Dynamics Investigation (GEDI) instrument on the International Space Station to assess the forest structure – such as canopy height and aboveground biomass – over the past four years.
To measure canopy height, the authors calculate the “RH98” value – the height of the top of the canopy or the nearest tallest vegetation in the area. This is an important measure of forest health and maturity. Aboveground biomass measures the aboveground woody biomass per unit area and is also a good measure of forest health.
They combine this with data from the Tropical Moist Forest dataset, which uses Landsat satellite imagery to show how tropical moist forests have changed over 1990-2022.
The plot below shows the canopy height for different types of moist tropical forests. The rows show intact forests at least 3km from a forest edge (top row), degraded forests (second row), the edges of forests (third row) and forest regrowth (bottom row), as shown in the maps below.
Darker blues indicate taller forest canopies. The map shows where the forests are located, and the bar charts on the right hand side show the overall distribution of different tree heights.
The tallest intact moist tropical forests are found in south-east Asia, where the average canopy height is 34m, the study finds. West and central Africa and Central and South America have average forest heights of 29m. This is because intact tropical forests in Asia, which are typically dominated by “hardwood wind-dispersed species”, are typically taller, the authors say.
The map also shows that degraded forests, forest edges and areas of forest growth have a greater proportion of shorter trees on average.
The forest edge
The study investigates two different types of forest edge effects, exploring how areas of deforested and degraded land impact nearby trees.
Dr Lilian Blanc is an author on the study and researcher at the French Agricultural Research Centre for International Development. He tells Carbon Brief that the effect of nearby degraded land “was not considered in previous studies”.
The graphs below show how areas of deforested land affect tree canopy height. The charts at the top show the average distribution of canopy heights of undisturbed forests in the Americas, Africa and Asia. The line colours indicate the distance of those trees from the forest edge, with yellow indicating a short distance and blue indicating a large distance.
The bottom map shows how far into the forest edge effects are present, by measuring the distance from the forest edge at which the height of the forest reaches 95% of the height of the intact, undisturbed forest.
The authors find the greatest edge effects from deforestation along the “forestation fronts of the Amazon”, in Borneo and Sumatra coasts marked by high fragmentation levels, and on the borders of the Congo basin.
They also record a decrease in canopy height up to 350, 400 and 1,500 metres from the deforested edge in the Americas, Africa and Asia, respectively.
The authors find that within 120 metres of trees that have been degraded due to logging and burning, the average canopy height in undisturbed forests is 15% and 22% lower, respectively.
The authors also investigate how quickly the forest can recover from logging and fires, concluding that while there is “fast regrowth of pioneer and understory species”, there is “no significant recovery in canopy height in the 30 years following the creation of a forest edge”.
Forest degradation can also increase the likelihood of deforestation, the authors say. They warn that forest height and distance to the edge of the forest are “strong predictors of deforestation”, as forest fragmentation makes the interior of the forest more accessible to loggers.
It adds that there has been selective logging 500 metres from the forest edge in Africa and the Americas, and even deeper in Asia.
Agriculture and road expansion trigger a 20-30% reduction in canopy height and biomass at the forest edge, with “persistent effects” measurable up to 1.5km inside the forest, the authors find. Blanc tells Carbon Brief that this is “an amazing result” as previous studies only looked for edge effects up to 120 metres from the forest edge.
The authors also calculated the edge effect using total above ground woody biomass, instead of canopy height. Using this metric, the authors conclude that the total area of forest with this edge effect is 18% of total global forest area in 2022 – an area more than 200% larger than previously estimated.
Prof Simon Lewis – a professor of global change science at University College London’s department of geography – tells Carbon Brief that this is a “striking new result”.
It implies that “the negative impacts on remaining forest from the creation of forest edges are much more extensive than has been commonly documented”. It also means that “forest protection of large blocks of forest is going to be more important than we previously thought”, he says.
Overall, the study is “an important step forward in monitoring forest disturbance, which is a very tough problem”, Lewis says. However, he adds that “care is needed” when looking at some of the observational data, saying that he “trust[s] the broad patterns of biomass loss following logging, edge creation and fires, but not the specific biomass loss values from these disturbances”.
Dr Peter Potapov – a researcher in the department of geographical sciences at the University of Maryland, whose work was cited extensively in the new study – says “the conclusion that edge effects are degrading 18% of the remaining humid tropical forest is an overstatement”.
He says that forest degradation depends on other factors, such as land-use regulations, and argues that “the assumption that all forests 1.5km away from the edges are degraded may undermine ongoing conservation efforts.
Expert response
These comments reflect the mixed response that the new study has received.
Prof Matthew Hansen – a remote sensing scientist at the University of Maryland’s department of geography – tells Carbon Brief that forest degradation is “a frustratingly elusive dynamic to quantify”. However, he praises the study for being “very clear and ambitious”.
Potapov, who has published research with Hansen, tells Carbon Brief that the results broadly confirm existing findings, but warns that there are some “major limitations” with the study.
For example, he says the method does not include a “matching technique” to separate the effect of human management on tree height from the natural factors such as elevation, soil quality and floods. He also warns that the observations “failed to correctly map anthropogenic disturbances in humid tropical forests”, adding:
“The authors greatly underestimate selective logging in Gabon, while the natural non-fire disturbances like river meandering and windfalls in South America were probably treated as human-caused degradation.”
Dr Flávia de Souza Mendes, a programme manager in forest and land use at satellite imagery firm Planet Labs, says the study is “well written”. However, she laments that “there are several local groups from the global south that have been studying this topic and are not part of this study”. She suggests that scientists carrying out similar studies should “invite more local researchers to take part”.
She also tells Carbon Brief that this paper “did not take into account studies carried out by local researchers on the relationship between degradation and deforestation”.
For example, she highlights a report by Brazilian researchers which finds that, in some regions of the Amazon, 86% of degraded areas were not subsequently cleared in the following decades. This is not in line with the findings of the new study, where degradation “has a crucial role in predicting future deforestation”, she says.
Prof Celso Silva-Junior – a research scientist in amazon ecology and remote sensing at Brazil’s Universidade Federal do Maranhão – tells Carbon Brief that the study “reproduces the findings of our research group, which has been investigating large-scale forest edge effects, using remote sensing technologies, since 2016”.
He says that the paper’s findings concerning biomass loss beyond 120 metres from the forest edge are “critical”. However, he emphasises the importance of the “local knowledge of tropical scientists” who are “deeply involved in the establishment of the conceptual framework for treating this relevant problem”.
The post Tropical forest degradation due to ‘edge effects’ is 200% higher than thought appeared first on Carbon Brief.
Tropical forest degradation due to ‘edge effects’ is 200% higher than thought
Climate Change
New York Already Denied Permits to These Gas Pipelines. Under Trump, They Could Get Greenlit
The specter of a “gas-for-wind” compromise between the governor and the White House is drawing the ire of residents as a deadline looms.
Hundreds of New Yorkers rallied against new natural gas pipelines in their state as a deadline loomed for the public to comment on a revived proposal to expand the gas pipeline that supplies downstate New York.
New York Already Denied Permits to These Gas Pipelines. Under Trump, They Could Get Greenlit
A “critical assessment” report commissioned by the Trump administration to justify a rollback of US climate regulations contains at least 100 false or misleading statements, according to a Carbon Brief factcheck involving dozens of leading climate scientists.
The report – “A critical review of impacts of greenhouse gas emissions on the US climate” – was published by the US Department of Energy (DoE) on 23 July, just days before the government laid out plans to revoke a scientific finding used as the legal basis for emissions regulation.
The executive summary of the controversial report inaccurately claims that “CO2-induced warming might be less damaging economically than commonly believed”.
It also states misleadingly that “excessively aggressive [emissions] mitigation policies could prove more detrimental than beneficial”.
Compiled in just two months by five “independent” researchers hand-selected by the climate-sceptic US secretary of energy Chris Wright, the document has sparked fierce criticism from climate scientists, who have pointed to factual errors, misrepresentation of research, messy citations and the cherry-picking of data.
Experts have also noted the authors’ track record of promoting views at odds with the mainstream understanding of climate science.
Wright’s department claims the report – which is currently open to public comment as part of a 30-day review – underwent an “internal peer-review period amongst [the] DoE’s scientific research community”.
The report is designed to provide a scientific underpinning to one flank of the Trump administration’s plans to rescind a finding that serves as the legal prerequisite for federal emissions regulation. (The second flank is about legal authority to regulate emissions.)
The “endangerment finding” – enacted by the Obama administration in 2009 – states that six greenhouse gases are contributing to the net-negative impacts of climate change and, thus, put the public in danger.
In a press release on 29 July, the US Environmental Protection Agency said “updated studies and information” set out in the new report would “challenge the assumptions” of the 2009 finding.
Carbon Brief asked a wide range of climate scientists, including those cited in the “critical review” itself, to factcheck the report’s various claims and statements.
The post Factcheck: Trump’s climate report includes more than 100 false or misleading claims appeared first on Carbon Brief.
https://www.carbonbrief.org/factcheck-trumps-climate-report-includes-more-than-100-false-or-misleading-claims/
Climate Change
Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund
We handpick and explain the most important stories at the intersection of climate, land, food and nature over the past fortnight.
This is an online version of Carbon Brief’s fortnightly Cropped email newsletter. Subscribe for free here.
Key developments
‘Deadly’ wildfires
WINE BRAKE: France experienced its “largest wildfire in decades”, which scorched more than 16,000 hectares in the country’s southern Aude region, the Associated Press said. “Gusting winds” fanned the flames, Reuters reported, but local winemakers and mayors also “blam[ed] the loss of vineyards”, which can act as a “natural, moisture-filled brake against wildfires”, for the fire’s rapid spread. It added that thousands of hectares of vineyards were removed in Aude over the past year. Meanwhile, thousands of people were evacuated from “deadly” wildfires in Spain, the Guardian said, with blazes ongoing in other parts of Europe.
MAJOR FIRES: Canada is experiencing its second-worst wildfire season on record, CBC News reported. More than 7.3m hectares burned in 2025, “more than double the 10-year average for this time of year”, the broadcaster said. The past three fire seasons were “among the 10 worst on record”, CBC News added. Dr Mike Flannigan from Thompson Rivers University told the Guardian: “This is our new reality…The warmer it gets, the more fires we see.” Elsewhere, the UK is experiencing a record year for wildfires, with more than 40,000 hectares of land burned so far in 2025, according to Carbon Brief.
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WESTERN US: The US state of Colorado has recorded one of its largest wildfires in history in recent days, the Guardian said. The fire “charred” more than 43,300 hectares of land and led to the temporary evacuation of 179 inmates from a prison, the newspaper said. In California, a fire broke out “during a heatwave” and burned more than 2,000 hectares before it was contained, the Los Angeles Times reported. BBC News noted: “Wildfires have become more frequent in California, with experts citing climate change as a key factor. Hotter, drier conditions have made fire seasons longer and more destructive.”
FIRE FUNDING: “Worsening fires” in the Brazilian Amazon threaten new rainforest funding proposals due to be announced at the COP30 climate summit later this year, experts told Climate Home News. The new initiatives include the Tropical Forests Forever Facility, which the outlet said “aims to generate a flow of international investment to pay countries annually in proportion to their preserved tropical forests”. The outlet added: “If fires in the Amazon continue to worsen in the years to come, eligibility for funding could be jeopardised, Brazil’s environment ministry acknowledged.”
Farming impacts
OUT OF ORBIT: US president Donald Trump moved to “shut down” two space missions which monitor carbon dioxide and plant health, the Associated Press reported. Ending these NASA missions would “potentially shu[t] off an important source of data for scientists, policymakers and farmers”, the outlet said. Dr David Crisp, a retired NASA scientist, said the missions can detect the “glow” of plant growth, which the outlet noted “helps monitor drought and predict food shortages that can lead to civil unrest and famine”.
FARM EXTREMES: Elsewhere, Reuters said that some farmers are considering “abandoning” a “drought-hit” agricultural area in Hungary as “climate change cuts crop yields and reduces groundwater levels”. Scientists warned that rising temperatures and low rainfall threaten the region’s “agricultural viability”, the newswire added. Meanwhile, the Premium Times in Nigeria said that some farmers are “harvest[ing] crops prematurely” due to flooding fears. A community in the south-eastern state of Imo “has endured recurrent floods, which wash away crops and incomes alike” over the past decade, the newspaper noted.
SECURITY RISKS: Food supply chains in the UK face “escalating threats from climate impacts and the migration they are triggering”, according to a report covered by Business Green. The outlet said that £3bn worth of UK food imports originated from the 20 countries “with the highest numbers of climate-driven displacements” in 2024, based on analysis from the Energy and Climate Intelligence Unit. The analysis highlighted that “climate impacts on food imports pose a threat to UK food security”. Elsewhere, an opinion piece in Dialogue Earth explored how the “role of gender equity in food security remains critically unaddressed”.
Spotlight
Fossil-fuelled bird decline
This week, Carbon Brief covers a new study tracing the impact of fossil-fuelled climate change on tropical birds.
Over the past few years, biologists have recorded sharp declines in bird numbers across tropical rainforests – even in areas untouched by humans – with the cause remaining a mystery.
A new study published this week in Nature Ecology and Evolution could help to shed light on this alarming phenomenon.
The research combined ecological and climate attribution techniques for the first time to trace the fingerprint of fossil-fuelled climate change on declining bird populations.
It found that an increase in heat extremes driven by climate change has caused tropical bird populations to decline by 25-38% in the period 1950-2020, when compared to a world without warming.
In their paper, the authors noted that birds in the tropics could be living close to their “thermal limits”.
Study lead author Dr Maximilian Kotz, a climate scientist at the Barcelona Supercomputing Center in Spain, explained to Carbon Brief:
“High temperature extremes can induce direct mortality in bird populations due to hyperthermia and dehydration. Even when they don’t [kill birds immediately], there’s evidence that this can then affect body condition which, in turn, affects breeding behaviour and success.”
Conservation implications
The findings have “potential ramifications” for commonly proposed conservation strategies, such as increasing the amount of land in the tropics that is protected for nature, the authors said. In their paper, they continued:
“While we do not disagree that these strategies are necessary for abating tropical habitat loss…our research shows there is now an additional urgent need to investigate strategies that can allow for the persistence of tropical species that are vulnerable to heat extremes.”
In some parts of the world, scientists and conservationists are looking into how to protect wildlife from more intense and frequent climate extremes, Kotz said.
He referenced one project in Australia which is working to protect threatened wildlife following periods of extreme heat, drought and bushfires.
Prof Alex Pigot, a biodiversity scientist at University College London (UCL), who was not involved in the research, said the findings reinforced the need to systematically monitor the impact of extreme weather on wildlife. He told Carbon Brief:
“We urgently need to develop early warning systems to be able to anticipate in advance where and when extreme heatwaves and droughts are likely to impact populations – and also rapidly scale up our monitoring of species and ecosystems so that we can reliably detect these effects.”
There is further coverage of this research on Carbon Brief’s website.
News and views
EMPTY CALI FUND: A major voluntary fund for biodiversity remains empty more than five months after its launch, Carbon Brief revealed. The Cali Fund, agreed at the COP16 biodiversity negotiations last year, was set up for companies who rely on nature’s resources to share some of their earnings with the countries where many of these resources originate. Big pharmaceutical companies did not take up on opportunities to commit to contributing to the fund or be involved in its launch in February 2025, emails released to Carbon Brief showed. Just one US biotechnology firm has pledged to contribute to the fund in the future.
LOSING HOPE: Western Australia’s Ningaloo reef – long considered a “hope spot” among the country’s coral reefs for evading major bleaching events – is facing its “worst-ever coral bleaching”, Australia’s ABC News reported. The ocean around Ningaloo has been “abnormally” warm since December, resulting in “unprecedented” bleaching and mortality, a research scientist told the outlet. According to marine ecologist Dr Damian Thomson, “up to 50% of the examined coral was dead in May”, the Sydney Morning Herald said. Thomson told the newspaper: “You realise your children are probably never going to see Ningaloo the way you saw it.”
‘DEVASTATION BILL’: Brazil’s president, Luiz Inácio Lula da Silva, signed a “contentious” environmental bill into law, but “partially vetoed” some of the widely criticised elements, the Financial Times reported. Critics, who dubbed it the “devastation bill”, said it “risked fuelling deforestation and would harm Brazil’s ecological credentials” just months before hosting the COP30 climate summit. The newspaper said: “The leftist leader struck down or altered 63 of 400 provisions in the legislation, which was designed to speed up and modernise environmental licensing for new business and infrastructure developments.” The vetoes need to be approved by congress, “where Lula lacks a majority”, the newspaper noted.
RAINFOREST DRILLING: The EU has advised the Democratic Republic of the Congo (DRC) against allowing oil drilling in a vast stretch of rainforest and peatland that was jointly designated a “green corridor” earlier this year, Climate Home News reported. In May, the DRC announced that it planned to open the conservation area for drilling, the publication said. A spokesperson for the European Commission told Climate Home News that the bloc “fully acknowledges and respects the DRC’s sovereign right to utilise its diverse resources for economic development”, but that it “highlights the fact that green alternatives have facilitated the protection of certain areas”.
NEW PLAN FOR WETLANDS: During the 15th meeting of the Ramsar Convention on Wetlands, held in Zimbabwe from 23 to 31 July, countries agreed on the adoption of a new 10-year strategic plan for conserving and sustainably using the world’s wetlands. Down to Earth reported that 13 resolutions were adopted, including “enhancing monitoring and reporting, capacity building and mobilisation of resources”. During the talks, Zimbabwe’s environment minister announced plans to restore 250,000 hectares of degraded wetlands by 2030 and Saudi Arabia entered the Convention on Wetlands. Panamá will host the next COP on wetlands in July 2028.
MEAT MADNESS: DeSmog covered the details of a 2021 public relations document that revealed how the meat industry is trying to “make beef seem climate-friendly”. The industry “may have enlisted environmental groups to persuade people to ‘feel better’ about eating beef”, the outlet said, based on this document. The strategy was created by a communications agency, MHP Group, and addressed to the Global Roundtable for Sustainable Beef. One of the key messages of the plan was to communicate the “growing momentum in the beef industry to protect and nurture the Earth’s natural resources”. MHP Group did not respond to a request for comment, according to DeSmog.
Watch, read, listen
MAKING WAVES: A livestream of deep-sea “crustaceans, sponges and sea cucumbers” has “captivated” people in Argentina, the New York Times outlined.
BAFFLING BIRDS: The Times explored the backstory to the tens of thousands of “exotic-looking” parakeets found in parks across Britain.
PLANT-BASED POWER: In the Conversation, Prof Paul Behrens outlined how switching to a plant-based diet could help the UK meet its climate and health targets.
MARINE DISCRIMINATION: Nature spoke to a US-based graduate student who co-founded Minorities in Shark Science about her experiences of racism and sexism in the research field.
New science
- Applying biochar – a type of charcoal – to soils each year over a long period of time can have “sustained benefits for crop yield and greenhouse gas mitigation”, according to a Proceedings of the National Academy of Sciences study.
- New research, published in PLOS Climate, found that nearly one-third of highly migratory fish species in the US waters of the Atlantic Ocean have “high” or “very high” vulnerability to climate change, but the majority of species have “some level of resilience and adaptability”.
- A study in Communications Earth & Environment found a “notable greening trend” in China’s wetlands over 2000-23, with an increasing amount of carbon being stored in the plants growing there.
In the diary
- 18-29 August: Second meeting of the preparatory commission for the Agreement on Marine Biological Diversity of Areas beyond National Jurisdiction | New York
- 24-28 August: World Water Week | Online and Stockholm, Sweden
- 26-29 August: Sixth forum of ministers and environment authorities of Asia Pacific | Nadi, Fiji
Cropped is researched and written by Dr Giuliana Viglione, Aruna Chandrasekhar, Daisy Dunne, Orla Dwyer and Yanine Quiroz. Please send tips and feedback to cropped@carbonbrief.org
The post Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund appeared first on Carbon Brief.
Cropped 13 August 2025: Fossil-fuelled bird decline; ‘Deadly’ wildfires; Empty nature fund
New York Already Denied Permits to These Gas Pipelines. Under Trump, They Could Get Greenlit
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