Northeastern seas rising faster than global average

 While the health of the Long Island Sound is arguably better than it’s been in 40 years, climate change brings another dimension to the complex issue as rising sea levels threaten to challenge the delicate balance between nature and human civilization.

Over the past two decades, the coastal corridor between Cape Hatteras, N.C., and Boston, Mass., has seen sea levels increase three-to-four times faster that the global average, according to a recent report by the U.S. Geological Survey.

Most scientists predict sea levels to rise worldwide by up to three feet by the end of this century, according to a report by the International Scientific Congress on Climate Change. Sea level rise in this part of the country has increased by 2-3.7 mm per year — or roughly a 10th of an inch — which the survey authors contend will continue and lead to an additional 8 to 11.4 inches of sea level on top of the global average.

Brian Thompson, director of the office of Long Island Sound Programs for the state Department of Energy of Environmental Protection, told The Darien Times that shoreline communities and marshland ecosystems are most affected by rising sea levels, which is believed to be caused by global warming and the Atlantic Ocean’s slowing circulation.

“As sea level rises, there in a natural setting, there would be opportunity for wetlands to migrate inland and establish new areas,” Thompson said, “but in a developed area — a very developed coastline — structures behind the wetland don’t allow them to migrate.”

This poses a threat to not only property owners who need to keep their homes and lawns from ending up underwater, but also to the fragile wetland ecosystems.

“…Water and wetlands are the foundation for the social, economic and environmental well-being of humanity across the globe,” according to a report drafted by the Institute for European Environmental Policy for the Rio+20 environmental summit that happened this year, the largest United Nations gathering in the organization’s history. “The recognition of the value of water and wetlands and integration into decision-making to ensure their wise use are, therefore, essential to meet our future social, economic and environmental needs.”

With nearly 17 miles of coastline in Darien — and 322 miles in Connecticut — private property owners remain on the front lines of protecting this ecosystem, and balancing that with the need to keep their properties livable can be a daunting challenge, Thompson said.

Michael Tone, chairman of Darien’s Environmental Protection Commission, said that as the coastline diminishes with the rising waters, property owners will have little recourse to save their property because of strict wetland regulations and protection measures.

“The use [of coastal properties] is restricted by setback requirements,” Tone said. “They may conduct activities within a regulated area, but if that regulated area migrates farther inland, the size of their usable property may be reduced.”

Trucking in sand to replenish washed away beaches can help to reduce erosion and withstand higher waters, Thompson said, although only some property owners can do this under current regulations.

“You can use an oyster reef in the water to dissipate energy before it gets to the shoreline,” Thompson said of other ways to mitigate rising seas. Structures are only allowed if all other options have been exhausted.

But treating symptoms palliatively does little to solve the reality of rising sea levels, Tone said. The recent study “is yet another report which underscores the importance of global warming and the consequences of it,” Tone said. “If in fact the projections in the report are valid and accurate… than it will have a significant effect on coastal communities sooner rather than later. It may not be next year, according to this report, but it may be sooner than many people would have anticipated.”

Sea level increases cannot only reduce coastal property owners’ lot sizes, but could also lead to salinization of groundwater supplies, which would most directly affect coastal homes with well water systems.

“This could be an increasing problem,” Thompson said. Others likely include coastal erosion, wetland and coastal plain flooding, salinization of aquifers and soils, and a loss of habitats for plants and animals.

Coastal areas would also likely be more prone to severe damage during bad storms, Thompson said — a reality that sinks deep for Connecticut residents who experienced two uncharacteristically damaging storms last year with Tropical Storm Irene and the Halloween nor’easter.

This year, state lawmakers passed legislation that updated the 32-year-old Coastal Management Act by requiring, among other things, that towns consider rising sea levels when planning coastal development to address receding shorelines, or what’s known as shoreline armoring.

“Cities in the hot spot, like Norfolk, New York and Boston, already experience damaging floods during relatively low intensity storms,” wrote Dr. Asbury Sallenger, a U.S. Geological Survey oceanographer. “Ongoing accelerated sea level rise in the hot spot will make coastal cities and surrounding areas increasingly vulnerable to flooding by adding to the height that storm surge and breaking waves reach on the coast.”

The U.S. Geological Survey report noted that the sea level rise in the northeast could be tied to changes in water temperature, salinity and density in the subpolar north Atlantic, which in turn affect ocean currents and eventually sea levels.

“Many people mistakenly think that the rate of sea level rise is the same everywhere as glaciers and ice caps melt, increasing the volume of ocean water, but other effects can be as large or larger than the so-called ‘eustatic’ rise,” Marcia McNutt, director of the U.S. Geological Survey, said in a press release. “As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property.”

Thompson noted that thermal expansion is the culprit for most increases of sea level — as oceans warm, the volume expands as the water particles move faster. While the jury is still out on the effect of anthropogenic global warming, most scientists agree that human beings have caused most of the global warming over the past 50 years, according to the Intergovernmental Panel on Climate Change.

Many environmentalists say residents can reduce their carbon footprint by driving more fuel-efficient cars, carpooling or taking public transportation, buying locally grown food and consuming products made by companies that have a sustainable and eco-friendly business models.

In the meantime, however, coastlines continue to recede. Thompson said he’s heard numerous stories about homeowners who lament their loss of land to the rising sea. Connecticut property owners have a little more flexibility to protect their coastal land with the new legislation, but ultimately nature can not be controlled.

Wetlands are some of the most biodiverse areas on the planet and act as carbon sinks, provide protection from floods and storms and regulate sediment transport, which contributes to land formation and coastal zone stability, according to a European report. They also help to replenish groundwater, retain and export nutrients, provide wetland products, offer locations for recreation and tourism, and regulate climate both locally and globally.

Nearly 9 million people live in the sound watershed, and the sound contributes roughly $8 billion annually to the regional economy through commercial and recreational activities, according to the Long Island Sound Study program.

Originally published in The Darien Times.

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