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
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The planet is heating up more quickly than ever before.
For decades, greenhouse gas emissions caused by human activity have been building up in the atmosphere and trapping ever-higher levels of heat.
The resulting asymmetry between incoming solar energy and energy radiated back out into space – known as “Earth’s energy imbalance” – provides a direct measure of the extent to which humans are disrupting the Earth’s climate system.
This imbalance is growing and in 2025 its 10-year average reached a record high, indicating that global temperatures could increase at even higher rates in the future.
This is among the headline findings of the latest “indicators of global climate change” (IGCC) report, published in the journal Earth System Science Data, which tracks changes in the climate system on an annual basis.
The report, now in its fourth iteration, has been produced by dozens of scientists from around the world.
Its findings are designed to fill the gap between Intergovernmental Panel on Climate Change (IPCC) science reports, which are published every 5-7 years.
In this article, we unpack the IGCC report, which explores how human activity is driving a growing energy imbalance and why monitoring systems to track global climate are so crucial.
(For more on previous IGCC reports, see Carbon Brief’s coverage in 2023, 2024 and 2025.)
Greenhouse gas emissions remain at an all-time high
Global greenhouse gas emissions are continuing to increase, mostly as a result of the use of fossil fuels. However, deforestation, agriculture and industrial processes also play an important role.
Over the most recent decade (2015-24), emissions stood at the equivalent of 54.6bn tonnes of carbon dioxide equivalent (GtCO2e) per year. In 2024, the most recent year for which we have complete data, emissions reached 56.8GtCO2e.
As the chart below shows, these emissions have pushed up atmospheric levels of CO2, methane and nitrous oxide. In 2025, concentrations of these gases reached 425.6 parts per million (ppm), 1936.3 parts per billion (ppb) and 339.4ppb, respectively.
This represents a rise of 3.8%, 3.8% and 2.2%, respectively, since the 2019 levels reported in the IPCC’s sixth assessment report (AR6).
At the same time, declines in emissions of aerosols such as sulphur dioxide, partly as a result of efforts to tackle air pollution, are increasing the Earth’s energy imbalance. This is because aerosols have a cooling effect on the Earth’s climate, counteracting warming from CO2 and other greenhouse gas emissions.
(Tackling sulphur dioxide, alongside other particulate emissions, remains critical because the immediate health and environmental damage they cause far outweighs their short-term cooling effect on the climate.)
The Earth’s energy imbalance is rising rapidly
The Earth’s energy imbalance has long been recognised as a key indicator of how the climate is being affected by human activities.
However, it is only in the last few decades that scientists have been able to record temperature changes deep enough in the ocean to accurately quantify it.
Earth’s energy imbalance measures how quickly excess heat is accumulating in every part of the Earth system, primarily in the ocean, but also in land, ice and atmosphere.
Through this accumulation of heat, the energy imbalance influences the rate of sea level rise and ice melt across the world, as well as increasing the frequency and intensity of extreme weather events, such as storms, floods and droughts.
Without human influence, the Earth’s energy imbalance would be close to zero.
But, as greenhouse gas emissions have built up in the atmosphere, the imbalance has been growing since the 1970s. Recent increases to Earth’s energy imbalance have outpaced those projections made by climate models — indicating the planet could see more warming than expected in the future.
As the right-hand chart below shows, the imbalance is now at a record high, having more than doubled over the past two decades.
It has increased by around 40% since 2019, from an average 0.79 watts per square metre (Wm2) over 2006-18, according to IPCC AR6, to 1.12Wm2 over 2013-25.
The left-hand chart shows how heat is accumulating in the ocean (blues), ice (grey), land (orange) and atmosphere (purple).
Global temperature rise
The excess heat building up in the climate system from the energy imbalance is pushing up global temperatures at a record rate of 0.27C per decade.
We estimate that human-induced warming – the amount of observed global surface
temperature increase attributable to both the direct and indirect effects of human activities – reached 1.37C in 2025. This has risen from 1.0C in 2017, as reported in IPCC AR6.
While natural variability in the climate system – such as El Niño or La Niña events – can also influence temperatures year-to-year, the upward temperature trend we are seeing is being driven by the persistent imbalance in energy.
We now expect global temperatures to exceed the Paris Agreement limit of 1.5C above pre-industrial levels around the year 2030.
This is significant because 1.5C has been identified as the critical dividing line between manageable climate risks and catastrophic, potentially irreversible damage to global ecosystems and human societies.
Heat accumulating throughout the Earth system
While heat is accumulating throughout the Earth system, it is not being distributed evenly around the globe.
Since the 1970s, around 90% of this heat has been taken up by the ocean, affecting marine ecosystems, ocean circulation patterns, sea level rise and climate extremes.
For example, the number of marine heatwave days – periods of unusually high sea surface temperatures – has more than tripled globally since the early 1990s. The year 2025 alone saw 65 days of marine heatwaves – meaning they occurred, on average, more than one day a week.
Meanwhile, the cryosphere – the portion of the Earth made up of frozen water, including glaciers, ice sheets and permafrost – is experiencing widespread ice loss and thawing in response to the growing energy imbalance. This affects ecosystems, sea level rise and infrastructure in polar and high-latitude regions.
Rapid warming has also resulted in record extreme temperatures over land, with average maximum temperatures for any single day over 2016-25 around 1.92C above pre-industrial levels). This is an increase of almost half a degree compared to the previous decade (2006-15).
Sea level rise and the energy imbalance
Sea level rise provides one of the clearest long-term signals of a changing planet.
It is closely linked to Earth’s energy imbalance. As heat accumulates in the ocean, water expands, raising sea levels. Meanwhile, a warming land and atmosphere means addition of water to the oceans through melting of glaciers and ice sheets, also adding to sea level rise.
Over the long-term, sea levels have been rising, on average, at a rate of around 1.8mm per year since 1901, totalling a record 23cm in 2025. This is increasing the risk of coastal flooding, erosion and habitat loss in many low-lying areas around the world.
This rise can be seen in the left-hand chart below, which shows observed global sea level changes from tide gauges (grey and blue dashed lines) and satellites (red dashed lines) since 1901. The solid lines indicate the average across multiple datasets.
Sea level rise is accelerating consistent with the observed increase in Earth’s energy imbalance. Over 2006-25, sea levels have risen at a rate of 3.67mm per year – more than double the rate of 1.69mm per year seen over 1976-95.
This increasing rate is shown in the right-hand figure below, which shows four successive overlapping 20-year periods and the most-recent decade.
(Last year’s transition from El Niño to weak La Niña conditions affected global rainfall patterns and led to a small and temporary fall in global average sea level in 2025. This explains the slight decrease in rate of sea level rise for the most recent decade, which is affected more than the 20-year period 2006-25.)
The bigger picture
Despite greenhouse gas emissions not increasing as rapidly as in the 2000s, this year’s IGCC findings continue to show how far and how fast the climate is changing due to human activity.
A significant increase in decarbonisation efforts in the second half of this decade is required to slow down the rate of human-caused warming and limit the escalation of climate risks and impacts.
These findings, like many others produced by scientists across the globe, rely on international expertise, partnership and the maintenance and availability of global climate datasets and the global observing programmes that underpin them.
This year’s edition of IGCC used more than 40 global datasets produced by research teams around the world, including the NASA satellite record of the Earth’s energy imbalance and the ARGO deep ocean float network.
However, a number of long-term monitoring programmes could be threatened by funding decisions made by governments around the world, most notably the Trump administration in the US.
Local meteorological data and weather balloon measurement programmes in many countries have declined in recent years, especially in Africa, the west Pacific and South America. This reduces scientists’ ability to monitor and understand key indicators of climate change.
This is not just an issue for climate science. Many of these observations are key to weather forecasts and systems that provide early warning for extreme weather. For example, media reports have suggested that recent reductions in weather balloon measurements in Alaska led to a lack of warnings for a recent winter storm.
The continuity and integrity of the climate observations that scientists use to understand how the climate is changing depends on effective and sustained coordination by international organisations, such as the Global Climate Observing System, the World Meteorological Organization and World Climate Research Programme.
Without this data and its coordination, future assessments will be much more difficult at a time when urgent climate action is needed.
The post Guest post: How a record-high ‘energy imbalance’ is driving global warming appeared first on Carbon Brief.
Guest post: How a record-high ‘energy imbalance’ is driving global warming
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