Global Sea Level Rise Under Highest Emissions Pathway

Source: UN Development Programme and Climate Impact Lab, November 2023

As Earth’s climate warms, sea levels around the world are projected to continue rising in the future. New data from Human Climate Horizons—a collaboration between EPIC’s affiliate Climate Impact Lab and the United Nations Development Programme—shows rising seas will impact the world’s dense and diverse coastal regions, which comprise only 2 percent of the world’s land area, but are home to 1 in 7 people. 

Over the next two decades, ocean levels along global coastlines are projected to rise an average of 9 centimeters under a very high emissions scenario and more than 55 centimeters—1.8 feet—by the end of the century. Certain areas of the world will experience even higher sea levels—including here in the United States. New Orleans and Houston, for example, could see ocean levels increase by 3.5 feet. Almost the entire East Coast sees oceans rise by at least 2.5 feet.

As the global mean sea level continues to rise in this very high emissions scenario, coastal flooding expands by the end of the century putting more than 97 million people in the path of expanding flood areas. This could trigger a reversal in human development in many low-lying regions along the coasts of Latin America, Africa, and Southeast Asia. Hundreds of highly populated cities will be exposed to increased flood risk, including land home to roughly 5 percent of the population of coastal cities including Santos, Brazil, Contonou, Benin, and Kolkata, India, by midcentury and that exposure doubles to more than 10 percent of the population by the end of the century.

This poses a multitude of challenges for coastal communities and ecosystems, with significant implications beyond flooding including accelerated erosion, the degradation of wetlands, increased salinization of soils and water reservoirs, and even the permanent loss of significant land and critical infrastructure. The Caribbean, Oceania and Small Island Developing States are on the front lines of this impact. Small Island Developing States, already confronting climate challenges, bear the greatest burden under this scenario, with 11 out of 23 countries projected to see 5 percent or more of their land permanently lost, including the Maldives, Marshall Islands, and the Bahamas.

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