Torrential rains in the Congolese capital Kinshasa in early April brought devastating floods that killed at least 165 people. As muddy torrents swept away cars and submerged homes, shown in shocking footage from the drenched city, residents were forced to swim or navigate canoes through inundated streets. 

The disaster, which displaced more than 7,000 people, came at the start of the 2025 rainy season and followed a series of similar floods across central Africa in 2024. In Kinshasa, floods that kill dozens of its residents are becoming almost an annual event. A group of climate scientists suggest Kinshasa could face similar deadly flooding every two years, according to a paper published by World Weather Attribution.

Rapid, unplanned urbanisation lies at the heart of the problem. With a population of around 450,000 in 1960, the Democratic Republic of Congo’s (DRC’s) capital has been transformed into a megacity with infrastructure that has failed to keep pace. Clogged drainage system, poor waste management and haphazard construction have left the city highly vulnerable to heavy rainfall.

This is only set to continue. The UN projects the DRC’s population will more than double by the end of the century. Kinshasa’s population is forecast to reach a staggering 83mn, making it the second largest city in the world after Nigeria’s capital Lagos and more than twice the current size of Tokyo, the world’s largest metropolis in 2025, according to a Global Cities Institute working paper.

Africa exposed 

The events in Kinshasa are a harbinger for urban centres across the developing world, particularly in the Global South. As climate change accelerates, its impacts – rising sea levels, intensified rainfall, longer droughts – are converging on cities already stretched by infrastructure shortfalls and population pressures.

The combination of geography and demographic momentum makes Africa especially exposed. “Population growth has become increasingly concentrated among the world’s poorest countries, most of which are in sub-Saharan Africa,” the United Nations Population Fund said when announcing its 2022 population growth projections. The region is the only one projected to still be growing by the end of this century.

Urbanisation is both a response to and a driver of climate stress. As rural areas face declining agricultural viability due to drought and soil degradation, migration to cities surges. In turn, sprawling urbanisation – often informal – amplifies the risks, overwhelming drainage systems and driving settlement into hazard-prone areas.

Risk consultancy Verisk Maplecroft has tracked the mounting dangers. In 2021, it found that 99 of the 100 cities most at risk from climate change were in Asia. But in a more recent analysis focussing on the fastest growing urban areas, sub-Saharan Africa dominates the rankings.

In a median warming scenario of 2.7°C by 2100, all of the 100 fastest-growing cities were deemed at high or extreme risk. That proportion jumps under higher emissions forecasts. Cities such as N'Djamena in Chad, Bangui in the Central African Republic, Kano in Nigeria and Zinder in Niger are seen as especially vulnerable.

“Many of these cities are facing significant threats, and those are going to be compounded by increases in population,” said Will Nichols, head of climate and resilience at Verisk Maplecroft, in an interview with bne IntelliNews.

El Niño adds to climate chaos 

El Niño added another layer of disruption in 2023 and 2024, further distorting weather patterns. Sub-Saharan Africa endured the most severe drought in over a century. Rainfall was delayed or absent, and temperatures soared. February 2024 was the driest in more than 100 years. These were also among the hottest years ever recorded.

Parts of the same region experienced severe floods as unusually intense rainfall struck 27 countries across Africa’s tropical belt, far exceeding historical averages. The resulting floods affected around 11mn people, according to the Africa Center for Strategic Studies, leading to an estimated 2,500 deaths and forcing 4mn from their homes.

 

A map published by the Africa Center for Strategic Studies shows heavy rainfall in 2024. Source: Africa Center for Strategic Studies/NOAA. 

Among them were over 200 residents of Kenya’s capital Nairobi, killed in one of the worst incidents of 2024, that displaced around 40,000 households after rains overwhelmed the city’s inadequate drainage systems. In Mathare, a sprawling informal settlement on a floodplain that is home to half a million people, entire communities were submerged. The government’s response only added to the problems; bulldozers were sent in to raze homes in flood-prone areas and resident were offered just KES10,000 ($75) to help them resettle elsewhere. 

“Africa is highly vulnerable to climate change impacts under all climate scenarios, with varying effects across the continent,” said Hayley Leck of ICLEI – Local Governments for Sustainability, a global network supporting sustainable urban development. “In urban areas, global temperature increases and changing precipitation patterns will be associated with more frequent and intense heatwaves, droughts, sea-level rise and storm surges (for coastal cities), and increased rainfall intensity contributing to flooding events.”

Leck told bne IntelliNews that cities are vulnerable not only because of exposure to climate-related hazards but also due to their limited capacity to cope. “Many cities are facing a complex mix of such challenges such as Nairobi where urban flash flooding together with seasonal water stress are pressing challenges,” she said. “As such, accounting for compounding, intersecting and cascading risks is critical.”

In Ghana’s capital Accra, early rains in the 2025 season have already triggered new floods. The World Bank previously warned that around 80% of Ghana's coastline is highly vulnerable to erosion and flooding, with some areas eroding at a rate of 4 to 12 metres annually. Such events are expected to become more frequent and severe, especially in cities across the central African belt. 

Flash floods – sudden, localised downpours that inundate cities – are becoming increasingly common across the globe. Climate change is intensifying these events, while rapid urban growth and poor planning are making them deadlier.

Unless cities can adapt, the combination of rising populations and worsening weather will make disasters more frequent, more severe – and more deadly.

Approaching ‘Day Zero’

Conversely, water scarcity poses an existential threat to many growing cities. Cape Town narrowly avoided “Day Zero” during an extreme drought in 2018, when taps were expected to run dry. Widespread appeals prompted residents and tourists to limit usage – flushing toilets less frequently, avoiding baths and delaying laundry – allowing the city to sidestep disaster.

Cape Town narrowly avoided 'Day Zero' in 2018. Source: Martina via Pixabay. 

Today, half a billion people endure severe water shortages year-round, according to a 2022 report from Christian Aid. Cities such as Cape Town, Amman in Jordan and Australia’s Melbourne risk losing up to half their water supplies. After over 15 years of drought, the Chilean capital Santiago, which previously resorted to rationing, could see losses exceed 50%.

Residents of Afghanistan’s capital Kabul have been forced to get water from tankers after the city’s worst drought in three decades. Its residents are forced to queue for hours to collect barrels of water, as reported by independent Amu TV. The situation is even worse in rural areas, leading to a wave of migration to the capital that has only worsened the situation. 

In Egypt, around 98% of its water comes from the River Nile, which is under threat from climate change and heavily used for agriculture, said the International Finance Corporation when announcing support for a project to boost the supply of safe drinking water in 2023. 

Even wealthy cities are not immune. London anticipates summer water deficits by 2050. “Day Zero – when water runs out and you can no longer turn on a tap – is a very real risk in major cities,” said Katherine Nightingale, global affairs director at clean water charity WaterAid, in an interview with bne IntelliNews.

One extreme to another 

The concurrent threats of floods and droughts are increasingly afflicting the same cities. WaterAid has identified a growing phenomenon of “climate whiplash”, where the world’s 100 largest cities face heightened risks from both droughts and flooding. The most affected are in Africa and Asia, where fragile infrastructure and poverty amplify exposure.

The charity’s analysis, spanning four decades of climate data and socio-economic factors, found nearly 17% of major cities now face both extremes, with 20% oscillating between them. Jakarta, already menaced by rising sea levels, is one of the worst-hit. Around 15% of cities surveyed – in Africa, Asia, the Americas and Europe – exhibit similar vulnerabilities, but those in South Asia and Africa are suffering the greatest impact due to underdeveloped infrastructure.

“Most cities were not created to cope with a set of climate extremes,” Nightingale explained. While they may have been built with heat or sporadic flooding in mind, “we are now dealing with extremes of drought and flooding”. As seen in Africa in 2024, “droughts harden the land surrounding cities, meaning that when the rain eventually comes, it is more prone to flood because of the harder earth,” said Nightingale. “Sanitation and water systems are not built to cope with this.” 

Scorching cities 

As the world warms, extreme heat presents another mounting hazard. All the main players predict that the world will warm by more than the 1.5°C Paris Agreement target by next year. They also predict that the average global temperatures will also broach the Paris maximum of 2C by 2036 or 2039 at the very latest, according to statistician Grant Foster and Stefan Rahmstorf, a German oceanographer and climatologist, as reported by bne IntelliNews.

The world is expected to warm by 4C between 2075 and 2090. Source: Grant Foster and Stefan Rahmstorf. 

C40, a global network of mayors of the world's leading cities, finds that 85% of North American cities, 83% in Europe and over half in Asia-Pacific, Africa, the Middle East and Latin America now identify extreme heat as a major threat.

Such heat can push human bodies to their limits. Around 50°C, organs begin to fail, with symptoms ranging from confusion to seizures. High humidity exacerbates danger through elevated “wet-bulb” temperatures – a measure of heat and humidity combined – which may already be exceeding safe thresholds in some regions.

The C40 report The Future We Don’t Want warns that without drastic emissions reductions, over 1.6bn residents – more than 40% of today’s urban population – will face frequent extreme heatwaves within three decades. Today, 200mn people live in cities where summer temperatures top 35°C. By 2050, nearly 1,000 cities could cross this threshold, with Asia, Africa and North America seeing the sharpest increases. Cairo, for example, may see summer highs surge from 34°C to 48°C.

Extreme heat disproportionately harms the elderly and children, while the urban heat island effect worsens outcomes in areas with limited green space. Heatwaves have an impact on businesses too, disrupting infrastructure and productivity.

The heatwave across much of the Middle East this May has had a severe human and economic toll. At least one military student died and eight others were hospitalised after suffering heat stroke in Iraq. In neighbouring Kuwait, rolling electricity blackouts were introduced after air conditioner use pushed power consumption into the red zone as temperatures soared close to 50°C. Syria has been fighting wildfires resulting from the lack of rain.

Iran's capital Tehran is regularly plagued by heatwaves, according to bne IntelliNews' reporters in the city. Source: Mohammad Shahhosseini via Pixabay. 

Cities underwater 

The other fearsome consequence of global warming is sea level rise. Data compiled by Climate Central paints a horrifying picture. Maps produced by the organisation show that by 2100, large parts of cities such as Bangkok, Basra, Dhaka, Kolkata, Jakarta, Lagos, New Orleans and Shanghai will lie below annual flood levels.

The Intergovernmental Panel on Climate Change (IPCC) projects a likely global mean sea level rise of between 43cm and 84cm by the end of this century relative to the 1986-2005 level. The US National Aeronautics and Space Administration (NASA) warns of a possible increase of up to two metres by 2150, alongside storm surges that may double in height. The implications for low-lying cities are profound.

Southeast and East Asia are especially vulnerable, said Kelly Van Baalen of Climate Central’s Sea Level Rise team. Many cities there are built on river deltas or low-lying coasts. Moreover, sea levels rise faster near the equator than near the poles, where melting ice exerts a gravitational pull on ocean water.

“The sea is rising at the same time as the river deltas are sinking,” Van Baalen told bne IntelliNews. “Natural erosion is compounded by human activity – building on deltas and pumping out groundwater.” Nowhere is this more extreme than Jakarta, where parts of the city are sinking by as much as 25cm a year. “Jakarta is the poster child for everything to do with sea level rise,” she said.

The Indonesian capital sits on a low-lying delta, its vulnerability exacerbated by seasonal monsoons, rising sea levels and inadequate or failing drainage systems. By 2030, large parts of Jakarta are likely to be below sea level. Floods are frequent, and saltwater intrusion into groundwater supplies is also worsening as the sea encroaches further inland. In response, Jakarta is planning a giant sea wall aimed at shielding the city and surrounding areas from flooding.

A map from Climate Central shows large parts of Southeast Asia are likely to be below sea level by 2011. Source: Climate Central. 

Elsewhere in Asia, other major cities face similar problems. Ho Chi Minh City, Bangkok and Shanghai are also sinking, multiplying the risks from sea level rise alone. “The consequences place millions of residents and trillions of dollars in physical and cultural assets at extreme risk,” said a report on the issue from the Stockholm Environment Institute. 

Some of Africa’s biggest cities are also struggling with rising sea levels. Parts of the Nigerian capital Lagos, forecast to be the world’s biggest city by 2100, are just one metre above sea level. As in Jakarta, flooding is a regular occurrence in parts of the city of 24mn people. In the north of the continent, beaches around the Egyptian port city of Alexandria are already disappearing, and there are now fears flooding could eventually force residents of the city and of the Nile Delta to relocate. Offshore lies a worrying portent, the underwater remains of the ancient port city of Thonis-Heracleion.

Storm surges 

Rising global temperatures are also fuelling more powerful storms. The 2023-24 El Niño event intensified extreme weather across the globe. Thousands were killed when Storm Daniel tore through Libya in 2023, wiping out as much as a quarter of the eastern city of Derna. Later, Cyclone Chido battered Mayotte with 120 mph winds. Hurricanes Otis and John struck Mexico, while Cape Town’s Khayelitsha township saw thousands of homes destroyed in storms. In April 2025, tropical Cyclone Jude claimed lives in Mozambique and Malawi, and rendered 30,000 homeless. In East Asia, Hurricane Helene brought devastation to Taipei and Tokyo.

The recurrence of violent storms and severe flooding is emblematic of the new reality. “Today’s 100-year flood is going to be tomorrow’s 10-year flood,” Van Baalen warned. Meanwhile, storm surges “are arriving on a higher platform, and storms are getting more intense because of climate change.” Despite modelling advances, she added, “we can’t say exactly how much worse the 100-year storm will be in the future.”

The effects of climate change are not confined to the Global South. Cities such as New Orleans, Miami, Venice and even London are facing mounting environmental threats. In October 2024, Spain’s Valencia saw over 230 fatalities after receiving a year’s worth of rain in a single day.

According to a 2024 survey by the Carbon Disclosure Project (CDP) non-profit, covering 1,131 cities, 83% report serious climate hazards, with flooding and extreme heat most frequently cited. Nearly two-thirds expect these threats to increase in frequency and severity. Cities in the Global South are particularly exposed, with limited resources hampering their ability to respond.

In the north, the Arctic faces its own perils. The thawing of permafrost is destabilising infrastructure across the region, including in Russia, Canada, Greenland and Alaska. The Arctic experienced record high temperatures this winter, and warming is now seven times faster in the North Barents Sea than the rest of the world, researchers have found. Catastrophic damage to Russian infrastructure worth over a quarter of a trillion dollars is now locked in, even if the Paris Accord targets are hit on time. Nearly 4mn people live in these permafrost zones, and “by mid-century, about 3.6mn of them could be affected by infrastructure damage”, said a new study published in Nature this year. 

Russia's Norilsk is the largest city inside the Arctic Circle. Source: City of Norilsk. 

The situation is worsened by the release of methane – a potent greenhouse gas (GHG) – as the frozen ground melts, creating a self-reinforcing climate feedback loop.

Unequal impacts

While climate change is a global issue, developing nations with fast-growing populations are disproportionately affected. Nichols explains that Verisk Maplecroft’s risk index incorporates a country's capacity for adaptation. “If you are trying to provide power, keep order… you have different priorities,” he notes, citing governance challenges, particularly in sub-Saharan Africa, where weak institutions and corruption compound climate vulnerability.

While cities like Tokyo, which face a multitude of environmental threats, have mitigated these with ample investment, cities in Southeast Asia and sub-Saharan Africa often lack the capacity to respond to cascading climate hazards.

Inequality also plays out within cities. “African cities are often characterised by stark contrasts in urban infrastructure,” says Leck, noting that affluent areas tend to have far more robust defences than marginalised communities. “There is an urgent need to rethink how we approach preparedness and adaptation,” she adds.

Rising sea levels, extreme heat and water scarcity pose existential questions for urban centres. While entire cities are unlikely to be abandoned, it is plausible that neighbourhoods may become uninhabitable or uninvestable.

Indeed, some of the cities deemed to be at high risk from climate change, among them Lagos, Jakarta, Khartoum and Kabul, are projected to experience explosive population growth in the coming decades. This is partly a product of climate-induced migration from rural areas into cities.

Economic toll 

The economic toll of climate change on urban life is mounting. Extreme heat disrupts industrial production and transport. Roads turn into rivers, employees are delayed, and factories must spend heavily on cooling. “I would be surprised if there was a sudden event where a city was completely decimated,” says Nichols, “but we are going to see a gradual shift from areas where it does become tougher to live.”

“The potential risk of asset stranding is a concern for many investors, and as such the savvy are taking steps to ensure adaption, improving resilience through climate risk assessments, upgrading and future proofing their investments,” said Paul Tostevin, head of Savills World Research. 

“There is risk that some assets in the highest risk areas may have to be abandoned when the cost of this investment exceeds the return, particularly for longer term climate patterns like sea level rise. Early indicators will be declining market value, exacerbated by unaffordable or even unavailable insurance cover.” 

As heatwaves strain transport and energy systems, the IPCC forecasts losses of up to 20% in certain sectors by 2050. Globally, this could amount to $2 trillion in damages by 2030, equivalent to India’s entire GDP.

Back in 2008, an OECD report projected that by the 2070s, up to 150mn people in port cities could be exposed to flooding and the value of at-risk assets could reach $35 trillion or 9% of expected global GDP.

The extent to which cities remain viable investment destinations will hinge on how well they adapt. “High climate risk locations aren’t necessarily of low resilience,” says Tostevin, pointing to Tokyo as a model. Despite exposure to floods, heatwaves, and seismic risks, Japan’s capital remains highly investable due to robust resilience strategies such as the Tokyo Resilience Project.

Fighting or adapting to change

Amsterdam also offers a lesson in long-term adaptation. Though below sea level, the Dutch capital has invested heavily in storm surge barriers, dikes and floating infrastructure. Adaptive architecture, such as buildings that rise and fall with the tides, is now part of the urban fabric.

Efforts to mitigate sea-level rise involve both curbing emissions and adapting to inevitable change. Physical defences – levees, breakwaters and restored wetlands – are being combined with nature-based solutions. These include creating green spaces that cool urban heat, absorb excess water and enhance wellbeing.

“We’re going to have to make a lot of coastal adaptations,” said Van Baalen. Cities face three choices, she adds: build to keep water out, adapt so flooding causes less damage, or retreat from the most vulnerable areas.

Adaptation strategies extend beyond coastlines. They include rainwater harvesting, early-warning systems and sanitation upgrades. WaterAid’s Katherine Nightingale stresses the importance of community involvement in policy-making. Inclusive consultations with schools, hospitals, businesses and households ensure that government strategies are grounded in local needs.

Green infrastructure is increasingly recognised for its multiple benefits. “The importance of nature-based solutions is becoming increasingly recognised,” says Leck. Blue-green infrastructure helps reduce flooding, store water and cool the urban environment.

Yet adaptation has its limits. Seawalls and raised infrastructure may buy time, but they cannot stop the seas from rising indefinitely. More aggressive emissions cuts are needed to stem polar ice melt.

However, political will is faltering. “We do have backsliding in climate action globally,” warns Nichols. The re-election of Donald Trump and his withdrawal from the Paris Agreement has weakened global cooperation. Meanwhile, the war in Ukraine has disrupted energy supply chains, prompting some European countries to temporarily fall back on coal.

Sea levels, however, are already rising – and will continue to do so for decades. “We’ve already emitted what will create another foot of sea level rise by 2050,” says Van Baalen. “What happens after that depends on the choices we make today. The future from here is up to us.”

This article is the first in a series on how the climate crisis is affecting major cities around the world.