Sea-level Rise and Coastal Flood Risk

Coastal wave

by Ryan L. Sriver

July 3, 2020

Sea-level rise poses considerable risks to Earth’s coasts. Many areas in the southeastern United States have already experienced increases in the number and severity of floods events in recent years, and the impacts are expected to worsen with future sea-level rise. Reliable projections of sea-level rise and variability, and careful characterization of the uncertainties, are critical for regional coastal flood risk assessments and adaptation planning. A major challenge now facing the scientific community is to characterize and communicate the uncertainties effectively, and to work with stakeholders and city planners to develop robust strategies to protect coastal investments.

Future projections of global sea-level are deeply uncertain. Best estimates of global sea-level rise in the year 2100 are around 2/3 of a meter. The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment (AR5) reported a “likely” sea-level range between roughly 0.5 and 1 meter by 2100 for a business as usual projection scenario (e.g. continuation of current trends in fossil fuel consumption). Here the term “likely” is meant to represent one-third of the probability of 2100 sea-level rise, thus two-thirds of the probability falls outside this range. The likely range does not capture the tails or potentially extreme sea-level rise scenarios greater than 1 meter, but these more extreme scenarios also pose the greatest risk and the potential for more severe floods.

Read the full commentary here.