Forests around the world are taking longer to recover from severe wildfires – potentially indicating forest decline, according to a new study.
The research, published in Nature Ecology & Evolution, finds a “significant increase” in the severity of forest fires from 2001-10 to 2010-21 – especially in western North America, parts of Siberia and south-eastern Australia.
It also finds that recovery from large fires has become “more difficult” for forests in recent years, particularly in the boreal forests of the far-northern latitudes.
Furthermore, fewer than one-third of all forests studied recovered successfully within seven years of a “megafire” – a broad term used to refer to extreme fires.
A “surprising discovery” was that fire severity had the largest impact on forest recovery – even more than climate change, one of the study authors tells Carbon Brief.
One researcher, who was not involved in the study, notes that the findings are “expected, but not previously reported on such a large scale”.
‘Significantly increased’ severity
The area burned by forest wildfires around the world increased by about 5% annually between 2001 and 2023, according to analysis from the World Resources Institute.
Burning forests release carbon dioxide (CO2) and these emissions can continue for years after the fire has been extinguished. CO2 emissions from forest fires soared by 60% globally between 2001 and 2023, a 2024 study found.
Fire can also harm plant and animal life in a forest, although it is not always harmful for ecosystems. Forests are sometimes burned in a controlled manner to clear debris and rejuvenate soils.
But more frequent and more intense wildfires, fuelled by climate change, can destroy forests and make recovery more challenging.
In the new study, researchers set out to assess whether intensifying fires and climate change have made post-wildfire forest recovery more difficult since 2010.
They use remote sensing data to identify 3,281 forest fires around the world larger than 10 square kilometres between 2001 and 2021. They focus on forests that were not impacted by deforestation or other fires in the seven years after a large fire took place, which the study describes as a “critical timeframe for recovery and reconstruction”.
Focusing on one-off, large fires allowed the researchers to “more accurately isolate” the drivers of the natural post-fire recovery and avoid the “confounding effects from re-burning disturbances”, Qiancheng Lv, a PhD student from Beijing Normal University, the new study’s first author, tells Carbon Brief.
They find that fire severity has “significantly increased” around the world, especially in boreal forests, since 2001, another author, Prof Ziyue Chen from Beijing Normal University, tells Carbon Brief.
This is the “primary factor” behind forests taking longer to recover from fires, the study finds. Chen adds:
“More concerningly, the adverse impacts of changing environmental conditions – especially rising temperatures and soil moisture deficits – on forest recovery are intensifying, necessitating urgent attention.”
The maps below highlight the difference in severity from large fires between 2001-10 (top) and 2011-21 (bottom). The researchers use an index called the differential normalised burn ratio (dNBR), which evaluates the level of burn damage after a fire.
They highlight five “hotspots” that frequently experience severe large-scale fires: western North America, northern South America, parts of Siberia, south Asia and south-eastern Australia.
Climate role
The research finds that all forest types experienced more severe fires since 2010, but that evergreen needleleaf forests were most vulnerable to damage.
Western North America and central and eastern parts of northern Siberia experienced the more severe fires, the study finds, and also saw the largest increase in severity after 2010. “Very few” forests in these two regions successfully recovered from fires within the study period – and most are still in the process of healing, the study adds.
The researchers use machine-learning models to assess the impact of different factors on post-fire recovery. Fire severity primarily influences initial recovery conditions, compared to climate factors, which impact successful vegetation regrowth.
They find that fire severity “had a more significant impact on forest recovery than climate change”. This “dominant role” was the team’s “most surprising discovery”, Chen tells Carbon Brief.
But, the authors note that current climate conditions “have become increasingly unfavourable” for forest recovery from fires, particularly due to rising temperatures.
The study finds that higher temperatures “generally accelerated post-fire forest recovery” before 2010, but had “strong negative impacts” since 2010.
Prof Chaoyang Wu, another author of the study from the Chinese Academy of Sciences, tells Carbon Brief:
“While numerous studies report beneficial effects of warming on vegetation greenness and productivity, our results suggest these benefits may diminish or reverse as temperatures surpass optimal ranges for photosynthesis.”
The chart below shows the different factors impacting forest recovery times. The differential normalised burn ratio – a measure of the damage caused by a fire – has the biggest impact, followed by temperature and soil moisture.
This finding contrasts with a 2024 study, which found that post-fire climate conditions had the biggest impact on forest recovery.
Accounting for this difference, Chen says that the new research focuses on “high-severity megafires”, whereas the 2024 study looks at all fire types. He adds:
“This finding highlights the critical need to account for fire scale in future post-fire recovery research, particularly as wildfire extent and intensity are projected to intensify under climate change.”
Forest recovery ‘stagnation’
The team uses multiple indices to assess three different aspects of forest recovery in the years after the fire: vegetation density, forest canopy structure and forest productivity.
The average time required for three indicators to recover to pre-fire conditions has increased by around 8% for vegetation density, 11% for canopy structure and 27% for gross primary productivity since 2010.
This results in overall recovery times that were several months to almost a year longer, compared to 2001-10 recovery times. The percentage of forests taking six years to recover from fires increased from around 11-13% before 2010 to 16-22% post-2010.
The first three years after a fire are “critical for forest recovery”, the researchers say, with many recovery assessments returning to upwards of 75% of pre-fire conditions during this time.
After this, recovery can slow down. The study finds that the percentage of forests experiencing this “stagnation” grew slightly from almost 23% before 2010 to almost 26% after 2010.
Prof Guido van der Werf from Wageningen University in the Netherlands, who was not involved in the research, tells Carbon Brief:
“It is a neat paper that quantifies something that is expected, but not previously reported on such a large scale: with increased fire activity in forests there seems to be slower recovery. This makes sense if fires are getting more severe due to climate change and, in some regions, due to having a growing fire deficit.”
The study finds that forests in humid regions generally recovered “relatively rapidly” after fires, while those in drier regions took longer. Around 60-80% of forests that successfully recovered from fires within seven years were located in humid regions.
‘Important analysis’
Dr Bernardo Flores, a researcher at the Federal University of Santa Catarina in Brazil, says the new work is a “very important analysis” that aligns with previous research.
Flores, who was not involved in this study, has researched the impact of fires and other disturbances on the Amazon rainforest. He tells Carbon Brief that these findings are a “bad sign for the world and also for tropical forests”, adding:
“If global forest flammability is rising, this will also affect tropical forests during drier years, as we saw in 2023-24 in the Amazon.”
The researchers note that few Earth system and vegetation growth models currently account for fires – and none account for changes in forest recovery time. Van der Werf tells Carbon Brief:
“One of the implications is that forests may shift sooner from being a [carbon] sink to being a source, or smaller sink, as increased fire activity and severity and slower regrowth means that less carbon is stored in forests and more in the atmosphere.”
The post Forests taking longer to recover from severe ‘megafires’ since 2010 appeared first on Carbon Brief.
Forests taking longer to recover from severe ‘megafires’ since 2010
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.