A new MIT-Princeton University study examining the prospective impacts of extreme storms and storm surges based on a range of climate change scenarios indicates that what were once 100-year and 500-year events would become 3 to 20 and 25 to 240-year events. The study can help coastal planners, who typically design coastal seawalls, buildings and other structures with a 60 to 120-year usable lifespan, according to an MIT News report.
The US may be already experiencing these climate change effects. This past year’s Hurricane Irene took an unusual track, cutting a long and wide path up the US Atlantic coast from mid-Atlantic through New England states, while Winter Storm Alfred battered New England unseasonably early. US state planning agencies and climate researchers, such as those in Vermont, are considering strengthening environmental conservation efforts, along with a host of other measures, to help plan for and mitigate the effects increasing frequency of intense storms, storm surges and floods pose.
“Climate data show that Vermont is experiencing more extreme rain events, and that trend is predicted to continue,” according to a report from the Climate Change Team at Vermont’s Agency of Natural Resources. More frequent heavy rainstorms are “expected to pose a recurrent challenge to our communities.”
Modeling Climate Change, Intense Storms and Storm Surge Floods
Combining four climate models, a specific hurricane model and three different models for predicting regional storm surges — one used by the National Hurricane Center — to study “current climate” (1981-2000) and “future climate” (2081-2100) scenarios, a joint MIT-Princeton University research team compared the results of multiple climate change-hurricane-regional storm surge simulations. Though the results varied, they all showed that the frequency of intense storms would increase due to climate change.
Using Battery Park City at the southern tip of Manhattan in New York City as a reference point, the researchers generated 45,000 storm simulations within a 200-km (~120-mile) radius. A 100-year storm there today means a flood surge of about two meters. A 500-year storm surge means three-meter high surge floods. Either would easily pass over the top of Manhattan’s 1.5-meter (4.95-foot) seawalls, noted MIT postdoctoral researcher Ning Lin, lead author of the study.
The highest recorded storm surge flood in New York City was 3.2 meters in 1821, which today would be considered a 500-year event, Lin noted. Under the scenarios analyzed by the research team, such storm surge floods would increase in frequency and occur once every 25 to 240 years. Storm surge floods of 2 meters, considered 100-year events today, would occur once every three to 20 years.
The research team’s report is available in the current issue of Nature Climate Change.
Enhancing Environmental Conservation to Mitigate Climate Change Effects
In Vermont, government planners are using the state environmental agency’s climate change report as a starting point for further studies, policy recommendations and climate change action plans. One, among many recommendations so far, entails strengthening conservation of the state’s rivers, forests and wetlands, which would enhance the ability of such areas to absorb water. Some such efforts are already underway.
One, along Otter Creek, which flows north through Vermont’s Bennington, Rutland and Addison counties into Lake Champlain, showed that Middlebury was less affected by flooding from the creek due to a series of wetlands between the Brandon and Middlebury.
“The floodwaters were less than half as high when they got to Middlebury, even though there were tributaries adding more (water),” Vermont Natural Resources Secretary Deb Markowitz was quoted as saying in CBS News’ report.
Image credit: NASA