Here’s the thing about climate change conversations: they often feel abstract. Polar bears, ice caps, distant tipping points. But when you start feeding real data into AI tools and asking a simple, direct question – which cities could be partially or largely underwater by 2070? – the answer stops feeling abstract very quickly. It starts feeling terrifyingly specific.
The list of threatened cities reads like a roll call of some of the most iconic, densely populated places on Earth. From Miami to Mumbai, from Bangkok to Venice, the data paints a picture that is hard to shake once you’ve seen it. So, let’s dive in.
1. Bangkok, Thailand – The World’s Most Vulnerable Capital
Honestly, the numbers for Bangkok are the ones that stopped me cold. Sea level rise projections put Thailand’s capital as the world’s most vulnerable city, and the low-lying metropolis has an average elevation of just 1.5 metres above sea level. That’s like standing on a single step above the ocean, city-wide.
According to the OECD, roughly half of the 10.7 million people living in Bangkok could be exposed to flood risk by 2070. Think about that for a moment. Half a city. Millions of people displaced by rising water.
Earth.Org’s sea level rise projections show Bangkok is at extremely high risk of sinking due to ocean thermal expansion and ice melt, and combined with the predicted increase in extreme weather events, one-third of the Thai capital could be completely submerged by 2050. The Thai government has faced sharp criticism from climate scientists for failing to implement meaningful preventive action.
2. Jakarta, Indonesia – A City Already Half Below Sea Level
In northern Jakarta, close to 90 percent of the metropolitan region already lies below sea level, and more than 60 percent of the city’s 10.6 million residents, particularly those in poor, informal high-density settlements, are vulnerable to flooding. This isn’t a future problem. It’s a present-day crisis.
Jakarta is especially susceptible to sea level rise since it is also experiencing one of the fastest land subsidence rates in the world – the digging of illegal wells is deflating the city from below, causing land to sink by 20 to 25 centimetres a year in certain areas of North Jakarta.
The city of Jakarta has been sinking so dramatically that in 2019, the government committed to relocating the capital of Indonesia to an entirely different city. That decision alone speaks volumes. When your government decides it’s easier to build a new capital than save the old one, you know the threat is real.
3. Miami, USA – America’s Most Exposed City
Miami is among the top three cities in terms of the value of assets exposed to coastal flooding between 2010 and 2070, with assets at risk estimated between 2 and 3.5 trillion dollars. No other American city even comes close to that figure.
Cities on the U.S. East Coast, including Miami, are particularly vulnerable, with sea level rise occurring two to three times faster than the global average. That acceleration matters enormously. It means timelines tighten faster than most planning models account for.
The state of Florida is investing roughly 4 billion dollars in preventing further damage, particularly to Miami Beach, a popular tourist destination with almost 1,200 homes currently already at risk of flooding. The defenses are being built, but researchers and scientists at the University of Miami continue to warn that the projections for 2060 and beyond show portions of the city becoming genuinely uninhabitable.
4. Shanghai, China – Economic Giant in Deep Water
Shanghai, a coastal megacity, faces risks of flooding that are magnified by its dense population and extensive economic activity. It is one of the most economically critical cities on the planet, and its exposure is staggering.
In Shanghai, coastal inundation currently amounts to only about 0.03 percent of local GDP, yet under a moderate emissions scenario it would increase to 0.8 percent by 2100 even without major adaptation efforts. That might sound small, but for an economy the size of Shanghai’s, even fractional percentage losses translate into hundreds of billions of dollars.
China has nearly 130,000 square kilometres of coastal area at or below 10 metres above sea level, making many regions prone to climate change-induced flooding and severe storms that threaten even non-coastal areas. Shanghai sits in the heart of this vulnerability zone, perched on the Yangtze River Delta with the sea pushing in from every direction.
5. New Orleans, USA – A City in a Race It Cannot Win
The devastating impacts of extreme weather on low-lying New Orleans were starkly demonstrated when Hurricane Katrina triggered deadly floods in 2005, with half of the city dropping below sea level, resulting in over 1,800 fatalities and an estimated 150 billion dollars in damage.
Recent satellite data reveals that some New Orleans neighborhoods, wetlands, and even sections of floodwalls are sinking by more than an inch per year, with some areas experiencing up to 47 millimetres of elevation loss annually. Here’s where it gets truly alarming: some of the concrete floodwalls and levees built to protect the city after Katrina are themselves sinking, with parts of the flood protection system losing elevation faster than sea levels are rising.
Under a more extreme scenario, which accounts for worsening weather events due to climate change, sea level rise could see the vast majority of New Orleans’ population displaced, making it by far the state’s most affected area. I know it sounds almost unthinkable, but the science consistently points in this direction.
6. Mumbai, India – Millions on the Front Line
Among India’s major coastal cities, Mumbai faces the highest flood risk, particularly under high-emission scenarios. This is a city of roughly 20 million people, and its low-lying coastal districts sit directly in the path of rising seas.
For present-day conditions, Mumbai ranks among the top ten cities in the world in terms of population exposed to a significant coastal flood event. The danger is not theoretical. Monsoon seasons already regularly flood large swaths of the city, and that’s before factoring in the additional pressure from rising sea levels.
The existence of flooding during storms and storm surges already affects Mumbai severely, and these conditions are expected to intensify significantly in the near future. A city that already struggles with annual monsoon flooding is being handed a much harder problem, with no easy exit in sight.
7. Venice, Italy – The Original Sinking City
Venice is almost the archetype of this conversation. The historic City of Venice has been severely exposed to repeated marine flooding since historical times due to the combined effects of sea level rise and land subsidence caused by both natural and anthropogenic forces.
Flooding occurrences known as “acqua alta” have dramatically increased, with St. Mark’s Square being submerged approximately 250 times a year by the 2020s. By 2024, the city had sunk an estimated 23 centimetres over the last century. That’s a sobering number for a place built on timber piles and history.
Efforts to protect the city include the construction of a complex movable barrier system called MOSE, designed to mitigate storm surges, though concerns remain about its long-term effectiveness in the face of escalating sea level rise predictions. It’s hard to say for sure whether Venice can be saved beyond 2070 without far more dramatic global emissions cuts.
8. Ho Chi Minh City, Vietnam – A Delta City Under Pressure
As global temperatures rise, sea levels are estimated to rise by more than one metre and nearly 20 percent of Ho Chi Minh City’s area will be flooded by 2100, resulting in the displacement of nearly 7 million people. The majority of those most at risk live in the Can Gio coastal district.
Vietnam, with its burgeoning population in the Mekong Delta and Ho Chi Minh City, faces significant challenges as these regions are highly susceptible to sea level rise and frequent flooding. The delta geography that made the region so agriculturally rich is now its greatest vulnerability.
Think of it like a flat dinner plate: any water that spills onto it spreads immediately and covers the whole surface. That’s precisely the geographic challenge Ho Chi Minh City faces, with no natural elevation to offer shelter or buffer as the seas creep higher year by year.
9. New York City, USA – A Megacity With Deep Vulnerabilities
New York City would be partially flooded under significant sea level rise scenarios, with Manhattan, Brooklyn, Queens, and Staten Island all underwater in certain areas. The city is already experiencing increasing frequency and severity of floods, having received its first flash flood emergency in recorded history in 2021.
Sea levels along U.S. coastlines are projected to rise by between 0.25 and 0.3 metres by 2050, and these impacts may be significantly exacerbated by coastal subsidence, a factor that is often underrepresented in coastal management policies and long-term urban planning.
Studies have shown that analyses failing to integrate subsidence alongside sea level rise assessments for New York City may yield inaccurate conclusions and potentially underestimate future flood risks. In short, the official projections may actually be too optimistic. That is a genuinely unsettling thought for a city of 8 million people.
10. London, UK – The Thames Barrier’s Ticking Clock
London built an intricate flood defence system completed in 1982, spanning 520 metres and lifting 10 steel gates to shut off the Thames’ flow, but experts warn that these barriers will not save the city from potential flooding past 2070, given the current pace of sea level rise.
Earth.Org found that, in the absence of new barriers and other preventive measures, roughly a quarter of London’s population, equivalent to almost 2 million people, faces displacement. That’s two million people in one of the wealthiest cities in the world. Wealth, it turns out, is no guarantee of protection.
High-tide flooding is now between 300 and more than 900 percent more frequent than it was 50 years ago across U.S. and major European coastlines, a trend that reflects the broader global trajectory. London’s flood defenses were engineering marvels of their era. Whether they are enough for the era we are now entering is a much harder question to answer confidently.
The Bigger Picture: A Global Crisis Without Borders
Under business-as-usual climate scenarios, the broader experience of sea level rise and flooding will be shared by over 570 cities throughout the world, from Miami to Guangzhou to Mumbai, exposing 800 million people and trillions of dollars in assets to ever harsher and more frequent climate hazards.
The population of low-lying coastal cities increased from about 360 million in 1990 to about 500 million in 2015, and a 2021 study found that between 197 and 347 million people now live in coastal areas less than 2 metres above sea level. The more people cluster on vulnerable coasts, the higher the stakes become with every passing year of inaction.
Estimates suggest the global economic costs to cities from rising seas and inland flooding could amount to 1 trillion dollars by mid-century. That number is staggering. Yet perhaps more staggering is this: the cities on this list are not small or obscure. They are home to hundreds of millions of people, trillions in economic infrastructure, and centuries of human culture. What happens to them by 2070 depends, in no small part, on choices being made right now.
What would you do if your city was on this list? Tell us in the comments.
