NOAA Report – by 2100, High Tide Flooding Will Occur ‘Every Other Day’

A report by the US National Oceanic and Atmospheric Administration (NOAA) says that by 2100, high tide flooding will occur at least ‘every other day’ in the USA.

The report (pdf) looks at rising relative sea level (RSL) under two scenarios: Intermediate Low (0.5 m global rise by 2100) and Intermediate (1.0 m global rise) and concludes that:

“by 2100, high tide flooding will occur ‘every other day’ (182 days/year) or more often under the Intermediate Low Scenario within the Northeast and Southeast Atlantic, the Eastern and Western Gulf, and the Pacific Islands with tidal forcing causing all (100%) of the floods except within the Eastern Gulf (80% caused by tides).”

By definition, ‘every other day’ high tide flooding would bring to fruition the saying championed by NOAA’s (late) Margaret Davidson:

“Today’s flood will become tomorrow’s high tide.”

The situation is worse under the Intermediate Scenario, with the report concluding “high tide flooding will become a ‘daily’ event (365 days/year with high tide flooding) within nearly all regions with tide forcing alone causing 100% of flooding.”

High Tide Floods Increased by 125% from 2000 to 2015

The report also found that between 2000 and 2015, annual frequencies of high tide flooding increased (median values) by about 125% (from 1.3 days to 3.0 days/year) along the Southeast Atlantic, by 75% (from 3.4 days to 6.0 days/year) along the Northeast Atlantic and by 75% (from 1.4 days to 2.5 days/year) along the Western Gulf.

“Currently, high tide flood frequencies are increasing at the highest overall rates (and likely becoming most problematic) along the coasts of the Southeast Atlantic and to a lesser extent along the Northeast Atlantic and the Western Gulf.”

High Tide Flooding Reports

The report from NOAA coincides with a study by researchers from the University of New Hampshire which shows that high tide flooding, often referred to as “nuisance flooding” has increased along the US east coast by 90 % in the last 20 years.

The University of New Hampshire study goes on to predict that by around 2050, nuisance flooding could occur almost daily at specific sites along the shores of Connecticut, New Jersey, Maryland, the District of Columbia, North Carolina, and Florida under an intermediate sea-level-rise scenario.

See the full NOAA report “Patterns and Projections of High Tide Flooding Along the U.S. Coastline Using a Common Impact Threshold.” (pdf)