Coastal

Coastal living carries risk as hurricanes and other coastal storms inflict trillions in property and infrastructure damage each year. Climate change will only elevate these risks. Rising sea levels will, over time, inundate low-lying property and increase the amount of flooding that occurs during coastal storms. Moreover, warmer sea surface temperatures may change the frequency and intensity of those storms.

Higher average sea levels due to climate change will lead to higher storm surges and elevated flooding risks in coastal communities world-wide, even if the intensity or frequency of storms remains unchanged. While the record 13.9 foot storm tide in New York Harbor during Superstorm Sandy was primarily due to the coincidence of the strongest winds with high tide, sea-level rise driven by historical climate change added more than one foot to that total.

Sophisticated new models can be used estimate potential losses from coastal storms under a range of climate change scenarios

While it is impossible to attribute any single storm to anthropogenic climate change, sophisticated new models can be used estimate potential losses from coastal storms under a range of climate change scenarios. These models are currently used by the insurance industry in underwriting flood and wind insurance products, by the finance industry in pricing catastrophe bonds, and by local officials in coastal communities in preparing for and responding to hurricanes and other coastal storms. These can be incredibly powerful tools for understanding how climate change will likely shape both industry and coastal community risk exposure in the years ahead.

Lab Findings

The Lab has found that the extent of coastal flooding has increased over the past 20 years as a result of sea level rise, meaning 14 million more people worldwide now live in coastal communities with a 1-in-20 annual chance of flooding. Continuing our current course of global greenhouse gas emissions (SSP2-4.5) is projected by the end of the century to expand this 1-in-20 floodplain to areas today populated by nearly 73 million people.

Hundreds of highly populated cities will face increased flood risk by midcentury, relative to a future without climate change. This includes land home to roughly 5 percent of the population of coastal cities such as Santos, Brazil, Cotonou, Benin, and Kolkata, India. Flood risk exposure is anticipated to double to 10 percent of the population by the end of the century.

Many low-lying regions along the coasts of Latin America, Africa, and Southeast Asia may face a severe threat of permanent inundation, part of an alarming trend with the potential to trigger a reversal in human development in coastal communities worldwide. By 2100, climate change is expected to cause the submergence of a significant share of land (>5 percent) in the following Small Island Developing States (SIDS) and Associate Members of United Nations Regional Commissions: Bahamas, British Virgin Islands, Cayman Islands, Maldives, Marshall Islands, Turks and Caicos, Tuvalu, and Seychelles.

At the highest levels of global warming (SSP5-8.5), approximately 160,000 square kilometers of coastal land (an area larger than the territory of Greece or Bangladesh) would be inundated by 2100, compared to a future with no climate change. This includes vast stretches of coastal cities in Ecuador, India, Saudi Arabia, Vietnam, and the United Arab Emirates—host of COP28. With concerted action to reduce global emissions and put the world on track to limit warming below 2 degrees Celsius (SSP1-2.6), 70,000 square kilometers of that at-risk land is projected to remain above sea level.