What is the difference between a "sea level projection" and a "sea level scenario"?

In the context of the IPCC AR6 and the 2022 Interagency Technical Report, a "sea level projection" is a detailed estimate of how much sea levels might rise over time, based on different levels of greenhouse gas emissions and climate models. These projections consider various possible futures, such as high or low emissions scenarios. The IPCC AR6 created sea level projections for a range of shared socioeconomic pathways (SSPs). On the other hand, a "sea level scenario" simplifies these complex projections into a few possible futures to help policymakers make decisions about coastal development, conservation, and infrastructure planning. These scenarios provide clear reference points for making informed choices about how to prepare for and adapt to sea level changes. The 2022 Interagency Technical Report created 5 sea level scenarios for the U.S. coastlines. These sea level scenarios are built from the sea level projections of the AR6.

See the Deeper Dive in the Future Sea Level section of About Sea Level Change for more details.