NOAA establishes ‘tipping points’ for sea level rise related flooding

A press release from NOAA: By 2050, a majority of U.S. coastal areas are likely to be threatened by 30 or more days of flooding each year due to dramatically accelerating impacts from sea level rise, according to a new NOAA study, published today in the American Geophysical Union’s online peer-reviewed journal Earth’s Future.

The findings appear in the paper From the Extreme to the Mean: Acceleration and Tipping Points for Coastal Inundation due to Sea Level Rise, and follows the earlier study, Sea Level Rise and Nuisance Flood Frequency Changes around the United States, by the report’s co-author, William Sweet, Ph.D., oceanographer at NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS). The new analysis was presented at a news conference today at the annual AGU fall meeting in San Francisco.

NOAA scientists Sweet and Joseph Park established a frequency-based benchmark for what they call “tipping points,” when so-called nuisance flooding, defined by NOAA’s National Weather Service as between one to two feet above local high tide, occurs more than 30 or more times a year.

Based on that standard, the NOAA team found that these tipping points will be met or exceeded by 2050 at most of the U.S. coastal areas studied, regardless of sea level rise likely to occur this century. In their study, Sweet and Park used a 1½ to 4 foot set of recent projections for global sea level rise by year 2100 similar to the rise projections of the Intergovernmental Panel for Climate Change, but also accounting for local factors such as the settlement of land, known as subsidence.

These regional tipping points will be surpassed in the coming decades in areas with more frequent storms, the report said. These tipping points will be also be exceeded in areas where local sea levels rise more than the global projection of one and half to four feet. This also includes coastal areas like Louisiana where subsidence, which is not a result of by climate change, is causing land to sink below sea level....

FEMA image from 2005, Houston evacuating from Hurricane Rita