by Maya Linson
Jan 29, 2009
Global sea levels could rise nearly 40 inches by the end of the century threatening the Atlantic coast with flooding, according to a recent report from the U.S. Environmental Protection Agency.
The new estimates nearly double the worst-case scenario presented in 2007 by the Intergovernmental Panel on Climate Change, which projected a global sea level rise of 7 to 23 inches by the end of the century.
Scientists are observing accelerated ice flow and melting glaciers due to global warming and many studies now estimate the increased rise in global sea levels as a result, the EPA report states.
Communities are faced with planning for two choices: hold back the water or prepare for nature to take its course.
Traditional responses to sea-level rise have included rebuilding homes and businesses at the same location or using engineering to hold back the sea water. But such responses may no longer be economical or even possible in some areas, according to the EPA report .
Parts of New York City would be at risk of submersion even with roughly 16 inches of local sea-level rise, according to studies in which Columbia University participated.
Because the additional water would weaken or destroy wetlands and flood protection, major storms could submerge Coney Island, much of southern Brooklyn and Queens, portions of Long Island City, Astoria, Flushing Meadows-Corona Park, Lower Manhattan, and eastern Staten Island, one study showed.
New York has created a dedicated state task force and held a series of meetings this month for public comment on the issue.
The task force will tap “the best available science to evaluate ways to protect New York’s remaining coastal ecosystems and natural habitats and increase coastal community resilience in the face of sea level rise,” according to the task force Web site. The task force will produce a final report by Dec. 31.
“Sea-level rise could be faster than what people had been thinking because at least one mechanism that people haven’t realized is possible,” said Claire Parkinson, a senior scientist and climatologist with NASA’s Goddard Space Flight Center in Maryland who was not involved with the report.
This mechanism involves crevasses in glaciers called moulins. “Melt-water from an ice sheet can flow rapidly down these moulins and the speculation is that therefore it could speed the outward flow of the ice,” Parkinson said. The IPCC did not address this mechanism in its 2007 report because no research had been published about it yet, she said.
The EPA report, “Coastal Sensitivity to Sea-level Rise: A Focus on the Mid-Atlantic Region,” involved the EPA, the U.S. Geological Survey and the National Oceanic and Atmospheric Administration. It outlines the impact of sea-level rise and strategies for regional preparation. States in addition to New York are taking steps to address the predicted threat.
“A number of state coastal zone management offices are starting to figure out what they really want to do to plan for accelerated sea-level rise,” said James Titus, project manager for sea-level rise at the EPA and a lead author of the report.
“This science assessment was done to inform anybody who wants to be informed about the state of the science,” he said. The problem, he noted, is that government leaders are making management decisions under the assumption that the sea level is stable.
But U.S. tidal wetlands in areas such as the Mississippi River Delta in Louisiana “are already experiencing submergence by relative sea-level rise,” the report states.
Scientists note that, in addition to flooding low-lying lands and wetlands, sea-level rise can bring flooding farther inland and cause other changes that fundamentally impact the environment and populated areas.
Wetlands are important because they provide flood control, act as a storm surge buffer and protect water quality, as well as house a variety of species. The consequences of wetland degradation were exemplified during Hurricanes Katrina and Rita in 2005.
Dense populations, other effects of climate change and susceptibility to storms and environmental stresses compound the problem for coastal regions, according to the report.
Although Titus said states including New York and Delaware are stepping up their response planning, he said the EPA researchers involved in the report expected no specific tasks to result from the report.
“What you expect and hope is that gradually people read it – people who might not have been up to date on the issue” and that ultimately it will help regional planners get ahead of the curve, he said.