One in three people in informal settlements in the global south live in floodplains and are at risk of a “disastrous flood”.
That is according to a new study published in Nature Cities, which measures the flood risk of global-south populations living in “slums” – as defined by UN-Habitat.
Using a combination of machine learning, satellite images, household surveys and socioeconomic data, the study finds that these slum populations are often concentrated in regions that have recently or frequently experienced severe floods.
Though large slum communities are vulnerable to floods, limited locational choices often mean that inhabitants have nowhere else to go, according to the study.
The research reveals the consequences of socioeconomic challenges when compounded with environmental pressures driven by urbanisation.
Dr Gode Bola, a water risk and climate scientist at the Congo Basin Water Resources Research Centre, who was not involved in the study, tells Carbon Brief:
“Slums in the Congo Basin used to face flooding to an extent that communities could deal with. Rainfall, which is where climate change is coming in, has meant people are facing larger floods and it’s difficult for people to adapt.”
Hotspots and vulnerability
According to the UN definition used by the study, slum households are those in urban areas that lack at least one of the following: “durable housing, sufficient living space, easy access to safe water, adequate sanitation and security of tenure.”
Using this, the study estimates that at least 17% of the global-south population, equivalent to more than 880 million people, live in slums. For some countries, such as Sierra Leone and Liberia, a majority of the population live in slums, the authors note.
Many of these slum communities are situated in areas that face substantial flood exposure. The study identifies northern India, Bangladesh, Nepal, Rwanda and the coastal regions of Rio de Janeiro as notable hotspots – as the map below illustrates:
Beyond physical exposure, these communities face social vulnerabilities that are exacerbated by flooding. Poor infrastructure, limited access to social services and a lack of institutional support impede effective responses to floods in these areas, the study finds.
At 80%, sub-Saharan Africa has the highest proportion of slum populations living in floodplains, the study finds.
Despite these challenges, relocation opportunities for people living in slums are slim. Financial constraints and reduced access to employment make it difficult to move to safer areas. Flood zones often offer cheaper land or housing, which pushes poorer households into vulnerable areas, the study finds.
For example, flood-prone areas in Mumbai in India, Dar es Salaam in Tanzania and Jakarta in Indonesia are considered “low value”, the authors say, making it more accessible to those in urban areas with lower incomes.
Nevertheless, the need for housing and an income continue to draw people to these flood-risk zones, separate research suggests.
Bola tells Carbon Brief:
“These slums are less expensive and poor people can afford the land. They buy this plot of land for life and asking them to relocate is asking them to have savings to buy another plot when there are no loans or government assistance.”
Disastrous floods
The authors mapped where slum populations are concentrated and where disastrous floods have historically occurred across 129 countries in the global south.
Disastrous floods were categorised in the study as events that resulted in “severe societal disruption, often leading to fatalities and severe humanitarian consequences”.
Their findings showed that, across the global south, those living in slums make up 35% of the total population, but account for 41% of those who live in flood-prone areas. This suggests that slum residents are more likely to settle in flood-risk areas in comparison to non-slum residents.
In fact, the study finds that in countries which often face disastrous floods, such as Bangladesh, slum residents are overrepresented in nearly all areas where disastrous floods have occurred.
Rourkela and Kinshasa’s slums
Floods in Rourkela, India, and Kinshasa, Democratic Republic of Congo, in recent months illustrate the issue of slums being situated in floodplains.
Heavy monsoon downpours caused floods in slum settlements in Rourkela, while floods and landslides devastated 13 communes in Kinshasa’s urban slums, resulting in 165 deaths.
In Kinshasa, rapid urban growth is pushing development into floodplains without proper infrastructure, making floods worse and recovery harder, according to a recent article by researchers. As a result, healthcare systems and transportation are routinely damaged.
In India, separate research suggests that slum settlements are prone to flooding because many are in low-lying areas on the periphery of water bodies, without proper storm-water drainage.
According to the new study, rapid urbanisation and land pressures will likely drive even more slum populations into flood zones in the global south, indicating that the cases of Rourkela and Kinshasa could become an even more frequent reality.
Flood protection
The “intensifying” effects of climate change amplifies the need to address the location of slums in the global south, the authors state.
However, other research has shown that minimal policies to support slum communities in flood zones exist. Yet, as rapid urbanisation occurs, slums continue to spread into high-risk areas.
Poor governance has failed to recognise the rights and needs of the urban poor in city planning, according to research from Cities Alliance.
The study in Nature Cities mentions that governments are often politically reluctant to formally recognise slums because doing so could increase pressure to deliver services, complicate future development plans or damage the international image of the city or country.
Dr Nausheen Anwar, director of Karachi Urban Lab and principal researcher and urban climate resilience lead at the International Institute for Environment and Development, tells Carbon Brief about the government response to flooding of informal settlements in Karachi in 2022.
Anwar, who was not involved in the new study, says:
“People were living alongside the banks of those specific channels and were quickly labelled as encroachers, even though many of them had tenure in these informal settlements and the supreme court essentially backed the entire plan for eviction. This is where the role of the law became very effective in displacing people and razing their homes.”
The authors of the study say their findings can be used to inform data-driven policies that address flood risk, as well as to help shape local regulations.
In the study, they call for governments to recognise the inequalities that slum populations face and to acknowledge slum communities as key stakeholders. This would mean considering their needs and interests when designing policies to respond to climate change.
The authors also suggest that communities be empowered through capacity building, including training in sanitation and waste management.
Anwar adds:
“Data speaks for itself whether it comes in the form of numbers or is quantitative or qualitative…We need that to buttress the sort of changes we want to make on ground in terms of influencing policy agendas and planning interventions, whether it is at the local scale or going up even at the global scale.”
The post Third of ‘slum residents’ in global south are exposed to ‘disastrous’ flood risks appeared first on Carbon Brief.
Third of ‘slum residents’ in global south are exposed to ‘disastrous’ flood risks
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 renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
UK greenhouse gas emissions in 2025 fell to 54% below 1990 levels, the baseline year for its legally binding climate goals, according to new Carbon Brief analysis. Over the same period, data from the World Bank shows that the UK’s economy has expanded by 95%, meaning that emissions have been decoupling from growth.
Spotlight
Bristol’s ‘pioneering’ community wind turbine
Following the recent launch of the UK government’s local power plan, Carbon Brief visits one of the country’s community-energy success stories.
The Lawrence Weston housing estate is set apart from the main city of Bristol, wedged between the tree-lined grounds of a stately home and a sprawl of warehouses and waste incinerators. It is one of the most deprived areas in the city.
Yet, just across the M5 motorway stands a structure that has brought the spoils of the energy transition directly to this historically forgotten estate – a 4.2 megawatt (MW) wind turbine.
The turbine is owned by local charity Ambition Lawrence Weston and all the profits from its electricity sales – around £100,000 a year – go to the community. In the UK’s local power plan, it was singled out by energy secretary Ed Miliband as a “pioneering” project.
‘Sustainable income’
On a recent visit to the estate by Carbon Brief, Ambition Lawrence Weston’s development manager, Mark Pepper, rattled off the story behind the wind turbine.
In 2012, Pepper and his team were approached by the Bristol Energy Cooperative with a chance to get a slice of the income from a new solar farm. They jumped at the opportunity.
“Austerity measures were kicking in at the time,” Pepper told Carbon Brief. “We needed to generate an income. Our own, sustainable income.”
With the solar farm proving to be a success, the team started to explore other opportunities. This began a decade-long process that saw them navigate the Conservative government’s “ban” on onshore wind, raise £5.5m in funding and, ultimately, erect the turbine in 2023.
Today, the turbine generates electricity equivalent to Lawrence Weston’s 3,000 households and will save 87,600 tonnes of carbon dioxide (CO2) over its lifetime.
‘Climate by stealth’
Ambition Lawrence Weston’s hub is at the heart of the estate and the list of activities on offer is seemingly endless: birthday parties, kickboxing, a library, woodworking, help with employment and even a pop-up veterinary clinic. All supported, Pepper said, with the help of a steady income from community-owned energy.
The centre itself is kitted out with solar panels, heat pumps and electric-vehicle charging points, making it a living advertisement for the net-zero transition. Pepper noted that the organisation has also helped people with energy costs amid surging global gas prices.
Gesturing to the England flags dangling limply on lamp posts visible from the kitchen window, he said:
“There’s a bit of resentment around immigration and scarcity of materials and provision, so we’re trying to do our bit around community cohesion.”
This includes supper clubs and an interfaith grand iftar during the Muslim holy month of Ramadan.
Anti-immigration sentiment in the UK has often gone hand-in-hand with opposition to climate action. Right-wing politicians and media outlets promote the idea that net-zero policies will cost people a lot of money – and these ideas have cut through with the public.
Pepper told Carbon Brief he is sympathetic to people’s worries about costs and stressed that community energy is the perfect way to win people over:
“I think the only way you can change that is if, instead of being passive consumers…communities are like us and they’re generating an income to offset that.”
From the outset, Pepper stressed that “we weren’t that concerned about climate because we had other, bigger pressures”, adding:
“But, in time, we’ve delivered climate by stealth.”