Swanson: A troubling future for Long Island Sound

Long Island Sound behind the historic Hempstead House Long Island Sound behind the historic Hempstead House in the Sands Point Preserve in Sands Point on the afternoon of January 9, 2014. Photo Credit: Newsday / Thomas A. Ferrara

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The Long Island Sound, formed by ancient glaciers, is a creation of climate change. And because of that, we can anticipate that it will be considerably different 50 years from now, because that change is accelerating.

This is the outlook of the recently published "Long Island Sound, Prospects for the Urban Sea," from the U.S. Environmental Protection Agency's Long Island Sound Study. The book, by oceanographic scholars -- including myself and several others at Stony Brook University -- summarizes the state of scientific knowledge about the Sound, documents environmental improvements and shortcomings that have resulted from attempts to manage the Sound, and discusses ecological concerns. It looks to the future, considering present knowledge and projected climatic alterations. And considering the projected path of climate change, the future for the Sound and its coastal communities is troubling.

The study began in 1985 and since then, sea level in the Sound rose at a rate of 1.5 feet per 100 years -- compared with one foot per 100 years experienced over the previous century. That rate is greater than the global average, and it's anticipated to increase considerably over the next 50 years. Shorelines will be quite different.

Low-lying areas will be permanently flooded. Many of Long Island's glacially formed bluffs will be severely eroded. The sediment from the sloughing hills may not be sufficient to maintain the low-lying sand spits that now define our North Shore harbors. Drowned Meadow may again be an appropriate name for Port Jefferson, as it was from the late 1600s to the early 1800s.

Ecologically important tidal marshes -- vulnerable to sea-level rise -- will continue to disappear, since their retreat will become limited as shorelines are hardened to protect property. As a result, fish-breeding and marine bird habitat will shrink.

Rising sea levels will bring saltwater intrusion into Long Island's groundwater -- an impact on potable water supply.

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The Sound's annual march of temperature, salinity and freshwater runoff will change as well. Peak discharges from the Connecticut and Hudson Rivers now occur frequently in March; 50 years ago, they typically occurred in April. This trend is likely to continue as winters become milder and there's less snow stored in the lands draining to them. Water clarity, thus light penetration, will increase in spring with the earlier river discharge, and that will boost the production of aquatic vegetation, stressing the organisms that live in the bottom waters.

The outlook from climate change could be ominous -- but not necessarily inevitable. The book concludes with a call for more research and suggests how the people around the Sound can prepare for and adapt to accelerated change.

Now is the time for forward-looking governmental leadership. We need to create detailed maps and charts of coastal areas to improve predictions of flooding from storms. We must move our homes and other structures back from the shoreline to allow for sea level rise and more extensive storm surges. Where possible, we must allow for salt marsh migration. There is also a need to develop and invest in new technologies to reduce stormwater runoff and sewage effluent from reaching the Sound.

And we need to embrace principles of ecosystem-based management -- looking at the organisms that depend on the Sound -- to improve the likelihood of leaving a healthy, productive Sound for the next generation. A first step is to implement coastal marine spatial planning, a process used by the marine community to guide wise use of ecosystems and preserve them.

Long Islanders must understand that our coastal waters will be a major determinant of how we will be able to use our land -- and live our lives.

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