Nearly a billion people in 600 coastal cities are vulnerable to sea level rise in the coming decades.
Sea level rise will create catastrophic difficulties for these communities and produce tens to hundreds of millions of ecological refugees. The consequences of the rising sea level will cause not only housing displacement, but water salinization and infrastructure destruction.
On the current heating trajectory, millions of people will be affected in cities such as Miami, Rio de Janeiro, Osaka and Shanghai. Sea level rise in Lagos, Nigeria could lead to 750,000 people without homes. In Alexandria, Egypt, hundreds of thousands of people living in the low-lying areas will need to relocate in the coming decades. While modest increases in sea level can be offset by some wealthier cities, many will not have the option for lack of resources or because geology does not permit and those cities will ultimately have to be abandoned.
In the US, it is not just Miami and New Orleans at risk, all of Florida and the gulf coast has seen a new tidal flood zone expanding well into highly populated areas. Houston, Baltimore and Charleston have already experienced flooding from rising sea levels. Coastal cities all along the Pacific and Atlantic Oceans face an increased risk from hurricanes, flood surges and tsunamis.
Food production in coastal areas will be hit by rising sea levels as well. Due to flooding and salt water intrusion the salinity of agricultural lands near the ocean increases. Salt intrusion in fresh irrigation water poses another problem for crops that are irrigated and renal failure for the populations that rely on that water.
Agricultural land in the Nile Delta is already impacted by salt water flooding. There is salt in the soil and irrigation water in the Red River Delta and the Mekong Delta in Vietnam. Bangladesh and China are also seeing similar impacts on agriculture.
Houston, the fourth most populous city in the US, is now a tidal flood zone. It’s not just rising seas causing flooding, it is also the sinking of land, thought to be from groundwater extraction. The Houston-Galveston area has already lowered by almost ten feet.
Shanghai, China is also sinking, but they have managed to slow it. Shanghai has stopped some of the groundwater extraction and in some places is pumping it back into the ground. As a result of this they have managed to raise parts of the city.
Dhaka, Bangladesh is sinking at a rate of a little over half an inch a year and sea level rise in the Bay of Bengal is about 10 times the global average. 1.5 million people have already migrated from coastal villages into the city’s slums.
Ten percent of the world’s population live in coastal areas that are less than 10 meters above sea level and two thirds of the world’s cities with over five million people are located in low lying coastal areas.