Global Warming Impacts on Estuaries and Coastal Wetlands

Coastal areas around the United States support thousands of species of fish and wildlife, and they are crucial for the regional economy, culture and quality of life. Healthy coastal habitats also protect us from the effects of hurricanes and flooding. However, coastal habitats and wildlife are under pressure from human activities such as development and pollution. Now, sea-level rise and other climate changes due to global warming will create even greater challenges for our coasts.

We are facing an ecological crisis that could see wholesale loss of wildlife populations and profound changes in our outdoor way of life.

We can improve the ability of our coasts to withstand sea-level rise by:

  • Enhancing the natural defenses provided by wetlands, barrier islands and reefs.
  • Supporting the natural replenishment of sediments from rivers and beaches.
  • Protecting inland buffers to enable habitats to migrate.
     

Learn about the specific impacts in the:

The Habitat

The nation has more than 88,000 miles of tidal shoreline harboring vast areas of coastal wetlands and more than 100 estuaries where major rivers enter the sea. These habitats are transition zones between freshwater and saltwater, and among the most productive habitats on Earth.

The nation's largest estuary—Chesapeake Bay—exemplifies the economic and aesthetic values of estuaries, even though significantly degraded from its historic productivity. This estuary alone supports more than 3,600 species of plants, fish and animals.

Louisiana is home to about 40 percent of the nation's coastal wetlands, sheltering more than 120 plant species. Estuaries and coastal wetlands contain important nursery areas for many marine species and harbor large populations of wintering waterfowl, ospreys, bald eagles and a diversity of other wildlife.

Benefits for Humans and Wildlife

Fishing, tourism and recreational boating associated with estuaries supports more than 28 million jobs in the U.S. In 2006, an estimated $491 million in fish and wildlife was extracted from Louisiana, with much of that dependent upon or from coastal wetlands. Chesapeake Bay waters alone produce some 500 million pounds of seafood for human consumption each year. Some 75 percent of commercial fisheries rely upon estuaries and coastal wetlands for habitat.

These areas improve water quality, provide flood control benefits, and dissipate storm surges, thereby helping to protect coastal areas. Important in rural economies, estuaries and coastal wetlands support both local subsistence needs and a strong recreational fishing industry.

Threats from Global Warming

Global warming has the potential to completely alter the structure and function of the nation's estuaries and coastal wetlands. Sea level rise threatens to inundate many coastal wetlands, with little room to move inland because of coastal development. Already sharply reduced in acreage, coastal freshwater wetlands are especially vulnerable to rising sea levels. In the next 100 years, taking into account the ongoing sinking of land in some coastal areas, net sea-level rise could exceed six feet.

Warmer water from global warming will alter the species composition and contribute to worsening dead zones and harmful algal blooms, increased incidence of marine diseases, and expansion of harmful invasive species.

Floods, droughts and other extreme weather events will alter water flows, leading to more polluted runoff and lower water quality. Stronger hurricanes and storms threaten to damage coastal wetlands, as demonstrated by Hurricanes Katrina and Rita which destroyed more than 100 square miles of Louisiana's coastal wetlands.

Conservation Investments to Minimize Global Warming Impacts

Extensive restoration of coastal wetlands has great potential to minimize the impacts on coastal communities of stronger hurricanes associated with global warming. This is because storm surges and hurricane strength are dissipated by coastal wetlands--a lesson learned too late in Louisiana.

Needed actions for restoration include diverting freshwater and sediment from the Mississippi and its distributaries, replanting marsh vegetation and closing channels that allow saltwater to flow into freshwater marshes.

Wherever coastal wetlands exist it will be necessary to account for sea level rise if commercial and recreational fisheries are to be retained at even near current values. This will require protection of current upland areas where coastal wetlands can develop as the sea level rises. It will also be necessary to improve storm water management to minimize exacerbated storm flows and keep stream temperatures down.

Increased monitoring of fish populations will be necessary so that commercial and recreational fishing regulations can be adjusted as populations are affected by changing water temperatures and quality.

Related Resources:

  • Swamping Louisiana - As the state's coastal wetlands disappear, at the rate of a football field every half hour, both wildlife and human lives are threatened.
     
  • Cypress Distress - The Gulf Coast's ancient cypress swamps have suffered through development, water diversion projects and Hurricane Katrina; now, there's another threat: the wood chipper.

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