Forget America's shining "city on a hill" --it's by the ocean where most of the world's greatest cities lie. For centuries, water has meant strategic advantages, like access to food and trade. But as Frank Jacobs writes in Foreign Policy, rising sea levels and disappearing coastlines mean that in many places what was once an advantage has become a liability. Could these 10 major cities soon vanish beneath rising tides?
Mumbai, 2.8 million inhabitants exposed
Mumbai sits on the western coast of India, on the edge of the Arabian Sea. A report this year by the Intergovernmental Panel on Climate Change noted that the city was facing increased risks from floods, storms, and rising seas. The city suffered massive flooding in 2005 when nearly three feet of rain fell over 24 hours, killing over 1,000 people. Above, Hindu devotees carry an idol of the elephant-headed Hindu God Lord Ganesha into the Arabian Sea for immersion in 2007.
Shanghai, 2.4 million inhabitants exposed
Shanghai -- the name in Chinese means "above the sea" -- is a low-lying city in the Yangtze River Delta. Researchers warn it is particularly vulnerable to climate change due to both its geography, and because of human factors: with upwards of 23 million people in the metro area, the city's drainage system needs improvement and lack of regulation has encouraged excessive construction in exposed areas. In the meantime, rising sea levels continue to wear away at the delta soil on which the city sits. Above, people take photos along the Bund as storm clouds gather over the Huangpu River in Shanghai.
Miami, 2 million inhabitants exposed
Miami and other southeastern cities in Florida are among the most vulnerable to climate change in the United States. The average elevation in Miami is just six feet above high tide; scientists predict sea levels could rise as much as five feet by 2100. At greatest risk are the city's power plants, airports, waste disposal sites, prisons, and hospitals. Above, a woman walks along the ocean as blustery winds blow through the palm trees with the approach of Hurricane Sandy.
Alexandria, 1.3 million exposed
Alexandria is strategically located on the Mediterranean Sea and is named after Alexander the Great, who made the city his capital. It's still Egypt's second-largest city, an industrial center, and its port handles four-fifths of Egypt's trade. But with the Mediterranean expected to rise between 1 foot to three feet over the course of this century, this ancient Egyptian city is now looking dangerously exposed. Above, a view of Alexandria's al-Manshiya Square on Egypt's northern coastline in July 2002.
Tokyo, 1.1 million exposed
Tokyo is located on a floodplain of three large rivers, and sits next to Tokyo Bay. But the 35 million people who live in the Tokyo metropolitan area have more to fear than rising sea levels; a study from 117 weather stations around the city showed that there's been a recent increase in the kind of highly localized, intense rainfall that can also lead to flooding. Above, the Rainbow Bridge connects Tokyo and Odaiba over the port of Tokyo.
Bangkok, 900,000 exposed
The Thai capital sits on the Chao Praya river. Nearly the entire city, once called "The Venice of the East" is built on swampland, and experts have warned that it is slowly sinking. Bangkok residents were besieged by flooding last year and some see it as a sign of what may come. Above, the Thai Royal Barge procession cruises down the Chao Praya river to celebrate the 60th anniversary of Thailand King Bhumibol Adulyadej's accession to the throne in 2006.
Dhaka, Bangladesh, 850,000 exposed
Dhaka, the capital of Bangladesh, is only 13 meters above sea level at its highest point. It sits between four flood-prone rivers and at the foot of the Himalayas. Researchers are concerned both about the impact of rising sea levels and also increasing snowmelt with higher average temperatures. Above, Bangladeshi boat men wait for passengers on the Buriganga river in Dhaka in September 2012. Thousands of Dhaka residents use the river to commute.
Abidjan, Ivory Coast, 520,000 exposed
Abidjan is the former capital of the Ivory Coast, and is still the country's economic capital. It sits, however, on the Gulf of Guinea, and rising sea levels have been steadily encroaching on houses and other infrastructure. Above, a view of Abidjan's coast in 2006.
Jakarta, 500,000 exposed
Jakarta sits near the sea, and is criss-crossed by 13 rivers; it experiences annual flooding almost every rainy season. But the Indonesian capital was hit by its worst flood in centuries in 2007. The water covered more than 70 percent of the city, sent 450,000 residents fleeing to high ground and were estimated to have caused nearly $700 million in damage. The Indonesian capital was paralyzed for days, prompting leaders to consider how climate change has made the annual floods even more treacherous. Above, heavy clouds hang over Jakarta on Feb. 18, 2010.
Lagos, 360,000 exposed
Lagos is one of West Africa's chief manufacturing and port cities. But teeming with more than 21 million people in the metro area, a lack of infrastructure, inadequate drainage, and uncontrolled buildup of settlements means that it is also among the places most vulnerable to climate change. Those most at risk are the people living in Lagos's poor urban slums, which already flood regularly, sometimes for days at a time. Above, people navigate through the waterways of the Makoko slum in Lagos, in September 2011.
