Climate change did not have a statistically significant impact on the wildfires that hit Chile earlier this month, according to a new rapid attribution study by the World Weather Attribution service (WWA).
In early February, a series of wildfires broke out across the coast of Chile. Within just days, they burned more than 29,000 hectares of land, destroying more than 7,000 homes and killing more than 130 people.
“The wildfires were the world’s deadliest since the 2009 Australia bushfires,” according to the WWA.
The authors warn that “global warming will likely increase the risk of fire conditions in central Chile” if temperatures rise by 2C above pre-industrial temperatures. Moreover, it is already making the country hotter and drier – both risk factors for wildfires.
The study finds that climate change had made the observed fire conditions more likely, but this result was not statistically significant, meaning it could have occurred by chance.
The findings are also subject to fairly wide uncertainty. One reason is that coastal Chile is seeing a slight local cooling effect, the researchers say, due to shifting weather patterns.
In addition, the study notes that changes in land use – such as the growth of informal settlements in forest zones and widespread conversion towards non-native species and monoculture plantations – are making many regions of Chile “significantly more vulnerable” to wildfires.
’Perfect storm’
Forest fires in the Valparaíso region in central Chile started on 2 February. They then “spread rapidly through mountainous forests near Viña del Mar, Quilpué and Villa Alemana… [and] moved extremely quickly into the outskirts of cities”, WWA says in a press release, leaving more than 29,000 hectares burned since 4 February.
Chilean president Gabriel Boric described the fires as “the biggest tragedy we have experienced as a country since the earthquake of 27 February 2010”, according to La Tercera.
The most up-to-date death toll remains at 132, Chile’s La Tercera reported, while El Mercurio reported on the mental health impacts of the fires, with affected people suffering from anxiety and stress.
According to Diálogo Chino, Boric said that evacuating people had been made difficult by the speed at which the fires were spreading – in some areas at more than 10km per hour, faster than most people can walk.
The map below, taken from the attribution study, shows the burned area across the Viña del Mar-Valparaíso sector, highlighted in red. The yellow circles show active fires on 2 February.
In an article by the NASA Earth Observatory, NASA research scientist Dr Elizabeth Wiggins suggested the wildfires “were the product of a perfect storm of conditions”, adding that “they occurred during a heatwave, drought and high-wind event borne from a combination of El Niño and climate change”.
Hot, dry and windy
The attribution study assesses the role of climate change on Chile’s fires between 31 January and 4 February, as these were the “highest fire intensity” days, when most of the impacts occurred, according to the study authors.
The intensity of a wildfire is influenced by a wide range of factors, such as atmospheric moisture, wind speed and fuel availability. The authors of this study focus on the “hot dry windy index” (HDWI) – a measure which combines maximum temperature, relative humidity and wind speed.
The study notes that this index does not take into account factors – such as the build-up of fuel – as other more “complex” indices do. However, the authors say the index is “an effective hazard metric for estimating threat to communities and difficulty of containment”.
The map below shows the maximum of average four-day HDWI between 31 January and 4 February 2024. Darker red indicates a higher HDWI, signifying hotter, windier and less humid conditions. The blue box indicates the study area.
To put the wildfire into its historical context and determine how unlikely it was, the authors analyse a timeseries of HDWI. They find that the hot, dry and windy conditions that drove the wildfires of February 2024 are a one-in-30 year event in today’s climate.
To assess the role that climate change played in creating these weather conditions, the scientists use climate models to compare HDWI in this coastal region of Chile in the world as it is today, with a “counterfactual” world without human-caused climate change.
This is one approach to attribution, the fast-growing field of climate science that aims to identify the “fingerprint” of climate change on extreme-weather events.
The study finds a “small increase” in the HDWI due to climate change, but says that the trend is not “statistically significant”. (A statistically significant result would mean that an HWDI index as high as that seen during the wildfires in Chile is unlikely to be explained by chance.)
The authors also assess the individual components of the HDWI – maximum temperature, relative humidity and wind speed – but again find no “significant” trend due to climate change.
The study also uses two different indices to assess the extent whether the natural climate phenomenon El Niño had any impact on the dangerous fire weather conditions, but again finds “no significant influence”.
Finally, using the same models, the authors assess whether the fire would be more likely in a warmer world. Although the impact of climate change on fire weather in this year’s Chilean wildfires is “not yet significant”, they find that “global warming will likely increase the risk of fire conditions in central Chile if warming reaches 2C” above pre-industrial temperatures.
(These findings are yet to be published in a peer-reviewed journal. However, the methods used in the analysis have been published in previous attribution studies.)
Coastal cooling
It is “not surprising” that climate change did not have a statistically significant impact on Chile’s wildfires, the study says.
The authors explain that the coast of Chile is one of the few places in the world where climate change is causing a slight local cooling effect, due to a high-pressure year-round weather system in the south-east Pacific Ocean called the “South Pacific High”.
The study explains:
“Climate change is causing the South Pacific High to move southwards, leading to stronger southerly winds that are pushing deep, cold water to the coast of Chile. These cold waters replace warm, superficial water in a process called ‘upwelling’, which causes low temperatures along the coast, unlike inland Chile and the rest of South America.”
Tomás Carrasco Escaff, a researcher at the University of Chile’s Climate and Resilience Research Center (CR2) and author on the study, told a press briefing that this shift in the South Pacific High results in “coastal cooling”, which drives down HDWI. However, he adds that it also causes “competing” effects of “greater dryness” and “intensification of wind”, both of which act to increase HDWI.
Coastal cooling is also tricky for climate models to capture accurately – especially as the fires broke out on the “transition between the coast, which is cooling, and the inland part of the country which has a warming trend”, explained Dr Joyce Kimutai, a research associate at Imperial College London.
This, combined with the limited observational data available, means that there is a “relatively large degree of uncertainty” in the results of the study.
Contributing factors
Local media has also reported on the potential drivers of the fires. Citing a recent study, La Tercera said that climate change and El Niño have made the country more prone to “megafires” – those spanning more than 200 hectares.
The research noted that megafires – such as the ones registered in the summer of 2017 and 2023 – were influenced by both the high temperatures driven by El Niño and more frequent and intense heatwaves. It also showed that the central regions from El Maule to Araucanía – to the south of the Valparaíso region – have been the most affected by megafires between 2014 and 2023.
Diálogo Chino cited a 2020 study from CR2, which found that “since 2010, forest fires in south-central Chile have increased in terms of occurrences and area burned, compared to the previous three decades, while the average duration of the fire season has also become longer”.
The article noted that the “fire-affected south-central zone of Chile has been transformed by vast forest plantations of exotic species, especially pine and eucalyptus, introduced for timber and pulp production”. The CR2 study found that “exotic plants can modify the dynamics of forest fires, increasing the speed of spread, as well as their extent, frequency, intensity and seasonality”, the article said.
Diálogo Chino also said that infrastructure in Valparaíso “is another factor explaining the scale of the fires”. It added:
“Some of the burned areas are densely populated, with their expansion having often taken place without planning permission. Additionally, many houses there are informal dwellings that may have been constructed with flammable materials such as wood.”
This aligns with the findings of the attribution study, which notes:
“Fire risk is increasing notably due to current land management practices, such as the expansion of Wildland-Urban Interface areas (including the growth of informal settlements in forest zones) and widespread conversion from native to foreign and monoculture plantations.”
In addition, Diálogo Chino reported that Chile’s minister of the interior and public security Carolina Tohá claimed at least some of the recent fires may have been started intentionally.
Analysis Chile’s National Forest Corporation (CONAF) found that the main cause of 64% of fires in Chile from August 2023 to January 2024 is “negligence”, followed by intentional and accidental fires, and then 0.5% directly started by lightning. Negligence is driven by agricultural burning, which contributed the most to the fires, forestry work and the poor condition of power lines, the analysis found.
New draft law
The fires caused widespread destruction, with BioBioChile reporting that 7,000 houses had been damaged or destroyed. The government has estimated the reconstruction cost at up to $1bn, the outlet noted. Of those homes, 70% were in informal settlements, the attribution study notes.
BioBioChile also reported on the deaths of wildlife – including owls, thrushes, foxes, partridge and chinchilla mice – as a result of the fires.
Pedro Álvarez, forest engineer and forest chair at Reforestemos, a Chilean civil society organisation that implements forest restoration and fire prevention projects, travelled to the affected area. He tells Carbon Brief that some of the ecosystems harmed were native forests – home to native species such as the Chilean palm – and sclerophyllous forests, which are composed of shrubs and trees.
Due to the scale of the fires, a new bill is being discussed in Chile’s congress, and – according to a CONAF press release – the minister of agriculture, Esteban Valenzuela, has urged that this is finalised by April this year.
The draft law aims to prevent forest and rural fires – for example, by implementing spatial planning instruments to set up “measures to manage landscape” and creating preventative management plans on forest land, such as fuel-cutting belts and clearance of combustible material.
Álvarez tells Carbon Brief that the biggest challenge facing Chileans and the state right now is rebuilding the area. He suggests that public policies should focus on preventing fires, enhancing spatial planning and restoring key regions for ecosystem services and biodiversity.
The post No ‘statistically significant’ link between climate change and Chile’s wildfires appeared first on Carbon Brief.
No ‘statistically significant’ link between climate change and Chile’s wildfires
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