Posted on February 16, 2022
With sea level rise poised to accelerate in the coming years, coastal communities around the country will need to manage a rapid escalation in flood frequency and severity, a new federal report finds, Andrew writes.
Driving the news: The report, led by the National Oceanic and Atmospheric Administration, shows that a century’s worth of sea level rise is in store for the U.S. during the next three decades.
Why it matters: Already there are coastal communities that regularly flood during astronomical high tides, a phenomenon known as “nuisance” or “sunny day” flooding.
- Once you add the amount of sea level rise expected in the contiguous U.S. by 2050 — about a foot above current levels on average — these nuisance floods will be transformed into frequent, damaging episodes.
Threat level: The report finds that, by 2050, moderate, high tide flood frequencies may increase by more than a factor of 10 nationally, along with a fivefold increase in major high tide flood frequencies.
- It notes that “significant consequences” are in store for coastal infrastructure, absent new efforts to reduce risk exposure.
- Moderate and typically damaging high tide flooding is projected to increase from an average frequency of 0.3 events per year in 2020 (the equivalent of having a 3% chance of occurring in a given year) to four events per year in 2050, the report finds.
What they’re saying: Ben Strauss, CEO and chief scientist of the research group Climate Central, said, “Just one foot of sea level rise will change a lot of American lives.”
- “Nationwide, about a million Americans live on land less than one yardstick above the high tide line. That jumps to five million below two yardsticks — the size of Houston plus Chicago, averaging almost 70,000 people per vertical inch,” he said via email.
- “Our national sea level threat has started slowly, but it’s going to accelerate like a rocket,” Strauss added.
- Jeremy Porter, chief research officer at the nonprofit First Street Foundation, said the findings “amplify concerns” raised in his work about the non-linear growth in sea level rise and flood risk.
- “The simple addition of a few inches of sea level rise exponentially increases the consequences of coastal surge events,” he said in an email.
