Sea Level 101
How Will Sea Levels Change in the Future?
Future sea level rise is tied to greenhouse gas emission levels.
Sea Level Will Continue to RiseSea Level Will Continue to Rise
The global sea level is rising due to human-caused climate change warming the planet. The planet warming is linked to greenhouse gas emissions. Thus, the more greenhouse gases that get added to the atmosphere, the more the global sea level will rise.
How much it 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, the most likely scenarios had sea levels rising 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 stop all greenhouse gas emissions today, the global sea level will continue to rise over the next few centuries. This will happen no matter when greenhouse gas emissions stop. This is because Earth’s climate is very large and complex. It takes time to cycle through changes and to reach a new balance.
Think of driving a car with no brakes. Right now our foot is on the accelerator slowly speeding us up as we add greenhouse gases to the atmosphere. If we take our foot off the accelerator, the car won’t stop right away. It takes some time to roll to a stop. Similarly, if we stopped greenhouse gas emissions today or removed some greenhouse gases from the atmosphere, the heat added to the planet needs time to rebalance and cycle out. And as long as the planet is warmer, land ice will melt and ocean water will expand, rising the global sea level.
Dive Deeper: How we create sea level scenarios and account for differences in future sea level rise from one location to the next.