Many of the world's biggest and most prosperous cities are coastal metropolises located close to large bodies of water. As climate change has increased the world's average temperature, water levels continue to rise all around the world as large packs of ice, such as glaciers, melt at accelerated rates.
This rise in sea levels result in greater destruction when severe weather or other natural phenomena cause surges of water to crash against the shores of big coastal cities. Typhoons, hurricanes and other events that previously would have caused minor problems now lead to chronic issues that cost billions of dollars.
Millions of people who live on the low-lying lands of these bustling cities are directly threatened by increased flooding, which promises to destroy their homes and livelihood. Trillions of dollars of assets around the world are also exposed to damage due to the current climate and sea level trends.
A study published by the Organization for Economic Co-operation and Development released details about the amount of risk coastal cities face due to climate change and flooding. These calculations outline cities facing the worst damage and population displacement under current conditions as well as estimates for the decade of 2070. The numbers suggest a sharp spike in consequences for these drowning cities.
11 Tokyo, Japan - Current: 1.11 million ; Projected: 2.52 million
Over 1 million residents of Tokyo are currently exposed to flood risks, with a total of $174 billion worth of assets in the path of rising water. Estimates project that during the 2070s, over $1.2 trillion in assets will be at risk with 2.5 million residents affected.
Tokyo already features a series of cavernous, underground flooding channels made of five tunnels that lead typhoon waters into nearby rivers. Some of the caves are big enough to fit a space shuttle worth of water. A cluster of powerful pumps expel 200 cubic meters of water per second in the pressure adjusting tank.
10 New Orleans, USA Current: 1.12 million ; Projected: 1.38 million
After the tragedy of Hurricane Katrina, the levees protecting New Orleans were repaired and upgraded to help reduce the amount of damage that takes place due to floods.
The current system cost $14.5 billion and is designed to eliminate almost all damage from 100-year floods. These new levees, pumps and floodwalls also protect against water surges that happen once every 500 years, which would be more powerful than Katrina.
About 1.12 million residents are exposed to flood risks that total $234 billion in assets. In 2070, those numbers are projected to increase to $1 trillion of asset exposure and 1.38 million people at risk.
9 Alexandria, Egypt - Current: 1.33 million ; Projected: 4.38 million
Alexandria is an ancient Egyptian city that was established in 332 BC by Alexander the Great. It was the capital of Egypt from its creation until 642 AD, when it was taken over by invading armies. It's currently the second biggest city in Egypt after Cairo.
This city's proximity to the Mediterranean Sea exposes 1.33 million citizens and $28 billion in assets to rising waters. By the 2070s, 4.38 million people will be at risk with a total of $563 billion in assets exposed to floods.
Over the past two decades, rising sea levels have claimed an average of about 58 meters of coastline each year.
8 Osaka, Japan - Current: 1.37 million ; Projected: 2.02 million
Osaka has a population of over 11 million, with 1.37 million exposed to flood risks, projected to reach over two million over the next 60 years. Current assets threatened by rising waters total $215 billion, predicted to increase to $968 billion around 2070.
The city of Osaka faces severe water damage through the flooding of several rivers, which can occur through a variety of means, also resulting in inland flooding. As much as 90% of Osaka urban areas are flatlands.
Typhoons and earthquakes that trigger tsunamis present a pair of constant flooding threats, with the city predicting up to a 70% chance of a nearby earthquake in the next 30 years.
7 New York-Newark, USA - Current: 1.54 million ; Projected: 2.93 million
New York and the adjacent area endured Hurricane Sandy in 2012, which ended up being the second costliest storm in U.S. history, killing at least 149 people and causing up to $50 billion in damage in the United States alone. A record storm surge of 13.88 feet was observed, as well as a wave measuring 32.5 feet high.
This disaster reflects the $320 billion in assets exposed to floods, which is predicted to grow to $2.14 trillion by 2070. 1.54 million people reside in at-risk areas, projected to grow to 2.93 million by 2070.
A recent contest that involved 148 teams of engineers, scientists and architects focused on plans to prevent another disaster as costly as Hurricane Sandy.
6 Kolkata, India - Current: 1.93 million ; Projected: 14.01 million
At present, 1.93 million Kolkata residents face flooding risks and by the time 2070 rolls around, that total will increase to a whopping 14 million people exposed. Assets threatened by floods will rise from $32 billion to $1.96 trillion during the same time period.
This city's proximity to the Bay of Bengal causes floods from the south to move across low lying lands to the north, which will become even more vulnerable as water levels around the world rise. Out of all the cities on this list, Kolkata is projected to experience the greatest increase in the growth of exposed assets by the 2070s.
5 Ho Chi Minh City, Vietnam - Current: 1.93 million ; Projected: 9.22 million
Ho Chi Minh City is the biggest metropolis in Vietnam, connected to the South China Sea through the Saigon River and Mekong River Delta. Experts from Rotterdam, Holland recently visited Ho Chi Minh City to help prepare for the effects created by climate change.
Half of this city is below one meter above sea level, with 70% of the land vulnerable to severe floods. Due to this geography, nearly 9.22 million residents will be exposed to rising waters threats by 2070, up from the 1.93 million currently exposed. Assets vulnerable to flooding will increase from approximately $27 billion to $653 billion over the next six decades.
4 Miami, USA - Current: 2 million ; Projected: 4.8 million
Despite efforts to protect this city against the impending effects of climate change, estimates state that exposed assets will increase from $416 billion to $3.5 trillion from now until 2070. The amount of people at risk from flooding will more than double, from 2 million to 4.8 million.
Most of the population lives around six feet above the sea. Despite efforts to protect Miami against the tides, some predict that by the end of the century tourists will be able to snorkel through submerged sections of the city with a rise of only three feet in water level. A rise of six feet would render most of South Florida unrecognizable.
3 Shanghai, China - Current: 2.35 million ; Projected: 5.45 million
Shanghai is China's biggest city and one of its most influential in terms of commercial and industrial activity, situated close to the Yangtze River, East China Sea and Hangzhou Bay. In addition to issues with rising water levels, the city deals with severe pollution from toxic emissions leaked from industry into rivers and other water sources.
The amount of people directly affected by flooding will double from 2.35 million to 5.45 million, while the assets exposed will skyrocket from $73 billion to about 1.8 trillion between now and 2070.
Shanghai plans to fight against rising water levels with a giant floodgate at the Yangtze River Delta.
2 Guangzhou, China - Current: 2.72 million ; Projected: 10.33 million
Guangzhou is the capital of Guangdong province and one of the biggest cities in South China. This city is connected to water through the Pearl River Delta, around 90 miles away from the South China Sea. Formerly called Canton, Guangzhou was the first commercial port visited by European traders.
Currently, 2.72 million people are at risk from floods, which will almost quadruple to 10.33 million residents at risk by 2070. $84.1 billion in assets are exposed to flooding damage, increasing to $3.4 trillion during the upcoming decades.
The State Oceanic Administration of China has recently ordered upgraded sewage, drainage and flood control systems to combat flood activity.
1 Mumbai, India - Current: 2.79 million ; Projected: 11.42 million
Mumbai received a glimpse of the extreme floods predicted to increase due to climate change in 2005, when an entire season's worth of rain fell in one day, causing a disaster that shut down water, electricity and other necessities. More than 400 people died and over 14,000 homes were razed.
In response to this severe event, a new drainage system is being constructed as part of an infrastructure plan to reduce the damage of floods.
Estimates suggest that $46.2 billion of assets are currently exposed to damaging water, which will rise to about $1.6 trillion by 2070. During the same time, the number of residents at risk will climb steeply, from 2.79 million to 11.42 million.