Research on climate change in urban areas is skewed towards large, well-established cities in the global north, according to analysis of more than 50,000 studies.
The research, published in Nature Cities, uses keyword searching and machine-learning methods to produce a database of studies on climate change and cities published over 1990-2022.
The authors find that small, fast-growing cities – especially in Africa and Asia – are underrepresented in their database.
“While cities like London, New York and Berlin are extensively studied, fast-growing cities such as Goma (Democratic Republic of the Congo), Surat (India) and Huế (Vietnam) are barely visible in the literature,” one study author tells Carbon Brief.
Inhabitants of these cities have collectively contributed very little to global greenhouse gas emissions, but face the greatest impacts from the warming planet, the authors say.
The paper finds that literature on climate change and cities is growing “exponentially”, with 84% of studies on this topic published over 2012-22.
The new analysis is published as scientists from around the world start work on the Intergovernmental Panel on Climate Change (IPCC) special report on climate change and cities, which is due for publication in March 2027.
The study finds that, in its most recent set of headline reports, the IPCC captured “only” 5% of the total available literature on climate change and cities.
One study author tells Carbon Brief that the study is a “call to action” for the IPCC and broader research community “to synthesise more, to look beyond familiar places and to take seriously the diversity of urban realities that will define the future of climate mitigation and adaptation”.
Climate change and cities
More than half of the world’s population live in cities. These densely populated areas are responsible for the majority of global emissions and are also hotspots for climate extremes, including heatwaves and flooding.
Research about climate change and cities is a fast-growing field that encompasses, among other topics, the impacts of climate change on city infrastructure, adaptation measures that city-dwellers are taking and technological measures to limit emissions from cities.
The IPCC’s upcoming assessment report will feature its biggest overview of research on cities to date, as the organisation has commissioned a special report on climate change and cities as part of its upcoming assessment cycle. The report’s outline has already been agreed and the final document is scheduled for publication in March 2027.
However, the new study argues that, without a dedicated effort to “pre-aggregate the underlying literature by the entire research community”, the IPCC “may struggle to deliver a balanced and comprehensive review”.
The new analysis is the “first global stocktake of literature” on climate change and cities, according to a press release from the University of Sussex. The research was produced in-part to help advise the authors of the IPCC report about the current landscape of literature on climate change and cities, the study authors tell Carbon Brief.
Author Dr Tim Repke is a researcher at the Potsdam Institute for Climate Impact Research. He tells Carbon Brief that he hopes that the new study “can serve as a starting point of searchable, clean data” to help the authors of the upcoming IPCC special report to “do their work more efficiently”.
A growing field
The amount of literature on climate change in cities is “much larger than previously estimated”, the paper says.
Moreover, the analysis points to “rapid, exponential growth” in literature on climate change and cities over the past three decades.
The graph below shows the number of studies about climate change and cities published each year over 1990-2022 (dark blue) and the subset of studies that focus on specific city case studies (light blue).
The plot also shows how many studies were published during the writing periods of each IPCC assessment report. For example, 37,539 studies on climate change and cities were published in time to feature in the IPCC’s sixth assessment cycle (AR6).
The authors find that 84% of studies in their database were published over 2012-22.
Literature on climate change and cities is currently growing 4.5 times faster than literature on climate change alone, they add.
Dr Simon Montfort is a postdoctoral researcher at Switzerland’s École Polytechnique Fédérale de Lausanne and lead author of the study. He tells Carbon Brief that the rapid growth in literature on climate change and cities is “not really surprising” because population growth in cities means that these areas are “becoming more and more important”.
The data can be explored further in their interactive online tool.
Uneven focus
There is a well-established skew in climate change literature towards wealthy nations in the global north. The new study finds that this skew is highly evident in literature on climate change and cities.
The map below shows the locations of the 20,000 “case study” papers. Darker colours indicate more highly researched areas. The map shows cities that were researched in one study (pink), between one and five studies (orange) and in more than five studies (red). The graph in the bottom left shows this information broken down by continent.
The authors identify more than 4,000 studies in Europe and 3,000 in North America. According to the authors, half of cities in these continents are covered by more than one study.
However, the map reveals a lack of research focused on cities in central and South America, Africa, the Middle East and south and south-east Asia.
The authors identify more than 8,900 studies focused on cities in Asia. One-third of these focus on Chinese cities, they find. The authors identify more than 1,500 studies on Beijing alone, most of which focus on mitigation, rather than impacts or adaptation.
Meanwhile, they find that 92% of cities in Africa are researched in no more than one study. Nigeria is the most highly studied country on the continent, with almost 400 studies – half of which focus on Lagos.
The authors identify a bias in their research database towards large cities with high emissions. Meanwhile, they find that small, fast-growing, non-coastal cities are underrepresented in the literature.
Prof Felix Creuztig is the head of the working group on cities at the Potsdam Institute for Climate Impact Research. He is an author on the study and on the upcoming IPCC special report.
He tells Carbon Brief:
“While cities like London, New York and Berlin are extensively studied, fast-growing cities such as Goma, Surat and Huế are barely visible in the literature. These smaller and rapidly urbanising cities in Africa and Asia are precisely where climate risks and emissions are increasing fastest, yet they are strikingly underrepresented.”
50,000 studies
To identify all existing literature on climate change and cities, the authors conducted their search using the open-access research database OpenAlex.
They first used a long list of keywords to search the abstracts of every paper on OpenAlex for research focused on cities and climate change. Keywords for literature on cities included “urban” and “built-up”, while key words for climate change ranged from “changing climate” to “carbon taxes”.
They then checked these papers using a “machine learning classifier”, which filtered out any research that was unsuitable.
The authors used a machine-learning approach to scan the abstracts of studies in their database, to determine which topics are most frequently covered.
More than half of the papers in the database were focused on mitigation, the authors found. The impacts of climate change on cities was covered in around 15,000 papers, and the rest covered adaptation and “cross-cutting” topics.
Lead author Montfort tells Carbon Brief that the database of 50,000 articles is “quite a precise sample, meaning that it includes few irrelevant articles”.
However, he adds that there may be “many relevant articles missing from our sample”. For example, the authors find that their database does not completely capture literature from the “physical sciences”, such as smart energy grids or radiative cooling methods.
Language is another notable bias, as the database only includes research published in English.
Dr Doan Quang Van is a researcher at Japan’s University of Tsukuba and a lead author on the upcoming special report. He praises the study, but notes that the English-only database likely leads to an “underappreciation of non-English regions”.
He also notes that Indigenous knowledge, which is “not necessarily contained in ‘official documents’ like papers or reports” is not included in the database.
IPCC recommendations
The authors compare the tens of thousands of studies cited by the IPCC in its most recent assessment cycle – AR6 – to their own database of literature on cities and climate change. They estimate that the IPCC cited almost 2,500 studies from the database in AR6, representing around 5% of the total.
They find that the IPCC’s choices about which studies to include further deepens the skew towards “large and mega cities” in the global north that is already evident in the literature.
Lead author Montfort tells Carbon Brief that the case studies are a “rich-evidence base” of “nuanced, case-specific knowledge”.
He says that it is important to expand the evidence base to less well-studied cities, but acknowledges it is “highly infeasible to conduct a study for every single city”. As such, he suggests that researchers should “look for ways to generalise findings from the more than 20,000 city-specific case studies already available”. He adds:
“If cities can learn from each other’s experiences, the existing evidence could go much further in informing city practitioners.”
To do this, the authors suggest that scientists should develop a data-driven method of grouping cities based on size, location and language, to enable “cross-city transfer learning from successful climate solutions”.
Dr Tamara Janes is a member of the climate information for international development team at the UK Met Office and an author on the upcoming IPCC special report. She was not involved in the new research.
She tells Carbon Brief that the study is “useful and timely”, adding that it “will undoubtedly help the ongoing special report by providing a solid foundational understanding for the current state of urban research worldwide”.
Janes adds that “this type of study is not only useful for researchers to design their research questions, but also for donor agencies as gaps in research can then be prioritised through flexible funding initiatives”.
Study author Crueztig says:
“For the IPCC and the broader research community, this is a call to action: to synthesise more, to look beyond familiar places and to take seriously the diversity of urban realities that will define the future of climate mitigation and adaptation.”
IPCC working group two co-chair, Dr Winston Chow, tells Carbon Brief that the “voluminous literature on climate change today presents challenges in its assessment”. He adds:
“Our experts are aware of these challenges towards developing reliable findings in informing our assessments and the IPCC is formally discussing this issue in a forthcoming expert workshop on methods of assessment.”
The authors add that they hope their interactive map, which is available online, will update automatically in the future to provide a “searchable, interactive, living database” of literature on climate change and cities.
The post Fast-growing, global-south cities are ‘strikingly underrepresented’ in climate research appeared first on Carbon Brief.
Fast-growing, global-south cities are ‘strikingly underrepresented’ in climate research
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”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewab