500-year floods could hit NYC every five years, study shows
Catastrophic flooding in New York City similar to destruction from Hurricane Sandy is predicted to become far more common in the coming decades, according to a study published Monday.
Rising sea levels from manmade climate change could prompt devastating, 8-foot floods that used to occur once every 500 years to happen once every 5 years by 2030 to 2045, the research said.
“Flooding in the nation’s largest city will be much higher and more frequent because sea levels will continue to rise at an accelerating rate,” the study said.
Five years ago this month, Sandy barreled into the Northeast, killing dozens of people and swamping parts of New York City under as much as 9 feet of water. In all, the storm caused $70.2 billion in damage.
Anywhere from 5 inches to
11 inches of sea-level rise is likely in New York City from 2000 to
2030, the study found.
The researchers based their analysis on multiple models that factored in predictions for sealevel rise and possible changes in the paths of future hurricanes.
Sea level has risen nearly 8 inches worldwide since 1880. Here’s why: As the Earth’s temperature warms, so do the seas. Heat-trapping greenhouse gases cause more land ice — glaciers and ice sheets — to melt and water to expand. Warmer water simply takes up more room than cooler water.
Scientists say global warming will be the primary cause of fu- ture sea-level rise. The greatest uncertainty is how quickly the massive West Antarctic ice sheet will melt.
The behavior of the planet’s major ice sheets, including the West Antarctic ice sheet, under a changing climate is still one of the biggest mysteries to be solved, said study lead author Andra Garner of Rutgers University.
While there remains some question about whether or not the West Antarctic ice sheet could collapse, “we have seen a number of recent studies that indicate that the ice sheets may be melting faster than previously thought,” Garner said.
But the study also contained one welcome surprise: Typical storm tracks may be farther off the East Coast in the future, potentially avoiding impact on land.
“Storm surge alone may not become much worse in NYC in the future because the larger surge from these stronger storms is compensated by the fact that storms in future simulations tend to be farther out to sea,” she said.
Future changes in sea level and storms would also be smaller if actions to slow climate change are taken, such as the Paris Accord’s goal of limiting warming to 3.6 Fahrenheit above pre-industrial levels.
“Human decisions about energy will be important in determining how much the sea rises and thus how much damage we face, and accurate projections of storms will help in minimizing the risks,” said Richard Alley, a professor of geosciences at Penn State University and a study coauthor.
The study appeared in the peer-reviewed journal Proceedings of the National Academy of Sciences.