Global and Regional Sea Level Rise Scenarios for the United States: Updated Mean Projections and Extreme Weather Level Probabilities along U.S. Coastlines

Authors

William V. Sweet, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
Benjamin D. Hamlington, NASA Jet Propulsion Laboratory, California Institute of Technology
Robert E. Kopp, Rutgers University
Christopher P. Weaver, United States Environmental Protection Agency
Patrick L. Barnard, United States Geological Service
David Bekaert, NASA Jet Propulsion Laboratory, California Institute of Technology
William Brooks, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
Michael Craghan, United States Environmental Protection Agency
Gregory Dusek, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
Thomas Frederikse, NASA Jet Propulsion Laboratory, California Institute of Technology
Gregory Garner, Rutgers University
Ayesha S. Genz, University of Hawai‘i at Mānoa, Cooperative Institute for Marine and Atmospheric Research
John P. Krasting, NOAA Geophysical Fluid Dynamics Laboratory
Eric Larour, NASA Jet Propulsion Laboratory, California Institute of Technology
Doug Marcy, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
John J. Marra, United States National Oceanic and Atmospheric Adiministration, National Centers for Environmental Information
Jayantha Obeysekera, Florida International University
Mark Osler, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
Matthew Pendleton, Lynker
Daniel Roman, United States National Oceanic and Atmospheric Adiministration, National Ocean Service, Silver Spring, Maryland
Lauren Schmied, FEMA Risk Management Directorate
Will Veatch, United States Army Corps of Engineers
Kathleen D. White, United States Department of Defense
Casey Zuzak, FEMA Risk Management Directorate

Date of this Version

2-2022

Document Type

Report

Citation

NOAA Technical Report NOS 01 (February 2022), 111 pages

https://oceanservice.noaa.gov/hazards/sealevelrise/noaa-nos-techrpt01-global-regional-SLR-scenarios-US.pdf

Comments

United States government work

Abstract

This report and accompanying datasets from the U.S. Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force provide 1) sea level rise scenarios to 2150 by decade that include estimates of vertical land motion and 2) a set of extreme water level probabilities for various heights along the U.S. coastline. These data are available at 1-degree grids along the U.S. coastline and downscaled specifically at NOAA tide-gauge locations. Estimates of flood exposure are assessed using contemporary U.S. coastal flood-severity thresholds for current conditions (e.g., sea levels and infrastructure footprint) and for the next 30 years (out to year 2050), assuming no additional risk reduction measures are enacted.

This effort builds upon the 2017 Task Force report (Sweet et al., 2017). In particular, the set of global mean sea level rise scenarios from that report are updated and downscaled with output directly from the United Nations Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6; IPCC, 2021a), through the efforts of the NASA Sea Level Change Team; updates include adjustments to the temporal trajectories and exceedance probabilities of these scenarios based upon end-of-century global temperatures. As with the 2017 report, these global mean sea level rise scenarios are regionalized for the U.S. coastline. In addition, methodology supporting the U.S. Department of Defense Regional Sea Level (DRSL) database1 (Hall et al., 2016) is adapted for the extreme water level dataset newly developed for this report.

This report will be a key technical input for the Fifth National Climate Assessment (NCA5). These data and information are being incorporated into current and planned agency tools and services, such as NOAA’s Sea Level Rise Viewer and Inundation Dashboard,2 NASA’s Sea Level Change Portal,3 and others. Although the intent of this report is not to provide authoritative guidance or design specifications for a specific project, it is intended to help inform Federal agencies, state and local governments, and stakeholders in coastal communities about current and future sea level rise to help contextualize its effects for decision-making purposes.

Key Message #1: Multiple lines of evidence provide increased confidence, regardless of the emissions pathway, in a narrower range of projected global, national, and regional sea level rise at 2050 than previously reported (Sweet et al., 2017).

Key Message #2 By 2050, the expected relative sea level (RSL) will cause tide and storm surge heights to increase and will lead to a shift in U.S. coastal flood regimes, with major and moderate high tide flood events occurring as frequently as moderate and minor high tide flood events occur today. Without additional risk-reduction measures, U.S. coastal infrastructure, communities, and ecosystems will face significant consequences.

Key Message #3: Higher global temperatures increase the chances of higher sea level by the end of the century and beyond. The scenario projections of relative sea level along the contiguous U.S. (CONUS) coastline are about 0.6–2.2 m in 2100 and 0.8–3.9 m in 2150 (relative to sea level in 2000); these ranges are driven by uncertainty in future emissions pathways and the response of the underlying physical processes.