How Will Sea Levels Change in the Future?

Sea Level Will Continue to RiseSea Level Will Continue to Rise

The global sea level is rising due to a warming planet. This warming is driven almost entirely by human activities that are generating greenhouse gas emissions.

How much sea level rises will depend on the amount of greenhouse gases added to the atmosphere moving forward. To explore the possibilities, scientists use emission scenarios. These show the possible range, from low to high, for the amount of greenhouse gases added to the atmosphere between now and 2100. The latest Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) from August 2021 used these emission scenarios to project sea level rise by 2100. They found that global sea levels could rise by anywhere between 0.9 to 3.3 feet (0.27 to 1.01 meters) by 2100, with even higher amounts possible depending on what happens with the ice sheets.

The 2022 Interagency Technical Report created five sea level scenarios to show different levels that sea level rise could reach in the United States. These include different levels of greenhouse gas emissions, global warming, and water added to the ocean from land ice melting. All of the scenarios had sea levels rising around 12 inches (0.3 meters) by 2050. Then, after 2050 those five scenarios diverge, with the most likely scenarios having sea levels rise from 2.3 to 4 feet (0.7 to 1.2 meters) by 2100 in the U.S. depending on greenhouse gas emissions today and in the future. Although, higher levels are possible in some locations, such as the Gulf Coast. Other factors, such as changes in land height and ocean currents, play a large role in local sea level change and will continue to do so in the future.

Scientists are continuously improving their understanding of how ice sheets and glaciers are melting. Thus, each time these values are calculated, they provide improved estimates of what could happen. If scientists find that the glaciers are melting faster than previously measured, then this will lead to a higher global sea level estimate for the future.

What If We Stop Adding Greenhouse Gases?What Happens If We Stop Adding Greenhouse Gases?

Even if we were able to stop all greenhouse gas emissions today or sometime in the future, global sea level will continue to rise over the next few centuries. This is because Earth’s climate is very large and complex, so it takes time to respond to changes and reach a new balance. The ocean stores enromous amounts of heat and releases that heat very slowly over time.

Think of driving a car and slowly pressing the accelerator. Adding greenhouse gases to the atmosphere is like pressing the accelerator and causing the car to speed up. Taking your foot off the accelerator does not stop the car immediately—the car continues moving as it gradually slows down. Similarly, if we stopped greenhouse gas emissions today or removed some greenhouse gases from the atmosphere, Earth’s climate system would need time to adjust. As long as the planet remains warmer, land ice will continue to melt and ocean water will continue to expand, causing global sea level to rise.

Dive Deeper: How we create sea level scenarios and account for differences in future sea level rise from one location to the next.

Next: What are the impacts of sea level change?