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Coastal Sensitivity to Sea-level Rise Report/EPA

This map details coastal and wetland areas across the Mid-Atlantic vulnerable to submersion at various rates of sea-level rise. The current rate is roughly 2 mm per year, while an additional 7 mm per year would total the estimated highest increase of 40 inches by 2100.

Sea levels rising at nearly double previous estimates due to global warming

by Maya Linson
Jan 29, 2009


Maya Linson/MEDILL

Click above to see areas of the Delaware Bay that the EPA in 2001 determined would flood at various levels of sea-level rise.

Key: 1.5 meters = 59 inches

Related Links

EPA ReportEPA sea-level rise mapsColumbia University's Center for Climate System Research

Hotter and higher: climate change causing sea-level rise

Experts agree that rising sea levels are a consequence of global warming. As the temperature gets warmer in frozen climates, ice caps melt and the resulting water causes the surface of the oceans to rise.

“Trends we see in the Arctic Ocean show that ice cover is decreasing,” said Brad Sageman, chair of Northwestern University’s Department of Geological Sciences. Because science suggests global warming is a certainty, “most of us who work in this business of climate change suspect that it’s already too late, that we’re in for the ride,” he said.

Carbon dioxide, a fossil fuel emission, has been accumulating for the past 150 years since the start of the Industrial Revolution. It is now significantly affecting the climate.

“It’s almost like eating a big Thanksgiving meal – it takes a while to move through your system,” Sageman said. “We put a big slug of CO2 into the atmosphere and now it’s going to take 150 to 200 years or more before you start to come down from the affects of that CO2 addition – before the greenhouse gas is removed by natural processes.”

And that assumes that emissions come under control.

Scientists are confident warming will take place, but the rate at which warming will occur is still unknown, Sageman said. Steps to mitigate climate change right now are critical, he said.

One strategy involves protecting natural systems called carbon sinks, which help keep CO2 from entering the atmosphere by sequestering it on Earth. For example, 13,000 acres of natural habitat in Illinois owned by The Nature Conservancy holds roughly 430,000 tons of CO2, according to Bob Moseley, the organization’s director of conservation for Illinois. That amount of CO2, which is bound up in the plant life and soil, is equal to emissions from about 50 million gallons of gas or driving a billion miles in the average American car, he said. 

Though the land was primarily acquired for biodiversity conservation, Moseley said, “land conservation really is one of the solutions [to climate change] – preventing the destruction of natural habitats.”

Sageman added that individual changes remain important. “If we don’t change our fossil fuel practices, we are likely going to guarantee significant consequences for our future descendants,” he said.

“If people had cared about us 100 years ago, we wouldn’t be in this situation—of course they didn’t know any better or understand the problem. But we do, so now we owe it to [future generations] to work on fixing it,” Sageman said. 

Scientists predict that global sea levels could rise nearly 40 inches by the end of the century, 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 in some glaciers and many studies now estimate the increased rise in global sea levels as a result, the EPA report, “Coastal Sensitivity to Sea-level Rise: A Focus on the Mid-Atlantic Region,” states.

Now, researchers said, planners are faced with 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 research from Columbia University. 

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, which involved the EPA, the U.S. Geological Survey and the National Oceanic and Atmospheric Administration, 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.