Washington, Dec 21 (IANS): Come 2050 and most of the US coastal areas are likely to be threatened by 30 or more days of flooding every year due to dramatically accelerating impact of rising sea level, says a study.

A team from the National Oceanic and Atmospheric Administration (NOAA) established a frequency-based benchmark for "tipping points" when the nuisance flooding occurs more than 30 or more times a year.

Such flooding is defined by NOAA's National Weather Service as between one to two feet above high tide.

"We find that in 30 to 40 years, even modest projections of global sea level rise will increase instances of daily high tide flooding to a point requiring an active, and potentially costly response," said William Sweet, oceanographer at NOAA's Centre for Operational Oceanographic Products and Services (CO-OPS).

The team found that these "tipping points" will be met or exceeded by 2050 at most US coastal areas studied, regardless of sea level rise likely to occur this century.

The authors used a 1A 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.

The research draws attention to the largely neglected part of the frequency of these events.

"This frequency distribution includes a hazard level referred to as 'nuisance': occasionally costly to clean up, but never catastrophic or perhaps newsworthy," said Michael Ellis, editor of the journal Earth's Future where the study is forthcoming.