Starting from a baseline of a sea level that will be two to three feet higher by the 2080s, the flood level highs produced by today’s 100-year storm would be more likely to recur, on average, as often as once in 60 to once in every 4 years by the end of the century.
A study by NASA’s Vivian Gornitz for the Office of Emergency Management (OEM) has been released as part of the scientific and technical expertise being marshaled to assist New York with its climate adaptation plans, because the rise of sea levels will create correspondingly higher flood levels during storms.
Among the more controversial solutions being considered are adaptive measures that include building seawalls and raising bulkheads as storm-surge barriers. Expensive rotating river barriers in the Thames have protected London from more frequent flooding over the last decade.
Because of the rise in sea levels expected by the 2080’s; storm surges will mean much more frequent major flooding in New York City than we see now. With climate change, the intervals between severe storms would also drop sharply. What is now a once in every ten years storm is predicted in climate models to occur yearly, or even more frequently – as often as every three months by the 2080’s.
The study’s author and her colleagues are skeptical that a too-piecemeal approach is being taken. But others feel that storm surge barriers are the only solution. “Unless the city’s going to evacuate and move up to the hills,” says Malcolm Bowman of the Stony Brook Storm Research Group, “they’re going to be there”.
At risk is major infrastructure at elevations of 10 feet or less. This includes three major airports–JFK, LaGuardia, and Newark, a number of highways, most area rail and tunnel entrances, and other important infrastructure, including subway system entrances in downtown Manhattan.
Forty city, state and federal agencies, comprising the New York Climate Change Adaptation Task Force are exploring all available options for dealing with the issue from experts at Columbia University’s Earth Institute and other organizations.
The frequency of hurricanes and violent storms has already more than doubled between the last two centuries. There were four major storms or hurricanes in the 19th century, and that increased to nine in the 20th century, three of which were Category 3 hurricanes.