Global warming-caused flooding “tipping points” are approaching in the U.S., a NOAA study warns as record snowfall descends on states from New York on to the northeast.
“Sunny-day” flooding is already a problem warns the study, “From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level rise,” by NOAA’s William V. Sweet and Joseph Park.
“Coastal communities are beginning to experience sunny-day nuisance or urban flooding, much more so than in decades past,” Sweet said, commenting on the study. “This is due to sea level rise. Unfortunately, once impacts are noticed, they will become commonplace rather quickly. We find that in 30 to 40 years, even modest projections of global sea level rise -- 1½ feet by the year 2100 -- will increase instances of daily high tide flooding to a point requiring an active, and potentially costly response, and by the end of this century, our projections show that there will be near-daily nuisance flooding in most of the locations that we reviewed.”
"Costal inundation" is coming with the tipping point, the study says:
“Projections of annual exceedances above local NWS nuisance levels at U.S. tide gauges are estimated by shifting probability estimates of daily maximum water levels over a contemporary 5-year period following probabilistic RSLR projections of Kopp et al. (2014) for representative concentration pathways (RCP) 2.6, 4.5, and 8.5. We suggest a tipping point for coastal inundation (30 days/per year with a threshold exceedance) based on the evolution of exceedance probabilities. Under forcing associated with the local-median projections of RSLR, the majority of locations surpass the tipping point over the next several decades regardless of specific RCP.”
Global warming is causing the sea level to rise, leaving the “tipping point” only a few decades away, it says:
“The current scientific consensus is that anthropogenically forced climate change is warming the planet and contributing to sea level rise [Cazenave and Le Cozannet, 2013] This climate warming has contributed to a global mean sea level rise (SLR) rate of ˜1.7 mm/year over the last century with higher rates of ˜3.2 mm/year over the last couple of decades [Church and White, 2011; Merrifield et al., 2013].
“Accordingly, the majority of locations will cross the 30 days/year (0.5 m above MHHW threshold) tipping point by 2050 under RSLR projections quite likely to occur (within the local 20% and 80% probability range of RSLR projections) and by 2060 under RSLR projections very likely to occur (between local 5% and 95% probability range of RSLR projections) from all three RCPs.”
The consequences of reaching the “tipping point,” the study warns, include tidal flooding, frequent road closures, and destruction of the nation’s infrastructure:
“Impacts from recurrent coastal flooding include overwhelmed storm water drainage capacity at high tide, frequent road closures, and general deterioration and corrosion of infrastructure not designed to withstand frequent inundation or saltwater exposure. As sea levels continue to rise and with an anticipated acceleration in the rate of rise from ocean warming and land ice melt, concern exists as to when more substantive impacts from tidal flooding of greater frequency and duration will regularly occur.”