Global Warming and Mangroves
Mangrove forests live in two worlds at once—at the interface between land and sea—anchoring their stilt-like roots in brackish waters where other plants cannot grow. In the United States, they are found along the coasts of Florida, covering some 469,000 acres from St. Augustine south on the Atlantic, and from Cedar Key south on the Gulf Coast. Four species of mangrove trees—red, black, and white mangroves, and buttonwoods—grow on Florida's offshore islands and tidal estuaries. They also are important in Puerto Rico and the Virgin Islands. In many tropical countries, mangroves are the prevalent ecosystem along low-lying estuaries and coasts.
Mangroves host a variety of fish and wildlife, including wading and sea birds, such as the great white heron and brown pelican, which roost and nest in the mangroves.
Benefits for Humans and Wildlife
Mangroves play a critical role in protecting lives and property in low-lying coastal areas from storm surges, which are expected to increase with global warming. They also stabilize shorelines and improve water quality.
Mangrove ecosystems serve as breeding, feeding, and nursery grounds for many shellfish, fish, and other wildlife. An estimated 75 percent of game fish, and 90 percent of commercial species in South Florida depend on mangrove ecosystems. Endangered species such as the Key deer live here.
The annual economic value of mangrove habitats is estimated at $80,000–$360,000 per acre.
Threats from Global Warming
Rising sea levels and changing salinity pose the most serious threats to these ecosystems. Where mangroves are sheltered by coral reefs killed by global warming, damage to mangroves from increased wave action is expected to rise.
Loss of mangroves will have a serious economic impact on both fisheries and coastal communities. In developing countries, mangroves have proven critical for saving human lives by their dampening of the wave heights and wind speeds during coastal storms.
Conservation Investments to Minimize Global Warming Impacts
With so little known, it will be important to monitor the responses of mangroves to global warming, and from this learn methods of minimizing these impacts and reestablishing mangroves. This will be especially important for assisting developing countries that depend on the health of these ecosystems for sustenance. Restoring mangrove vegetative cover and ecological functions can cost up to $87,000 per acre.
Unable to directly control sea level, managers will need to ensure that other human stresses on mangroves are minimized to give mangroves the best opportunity to withstand the duress of global warming impacts. This may require, for example, improving land-use management and stream water quality on nearby lands. Other possible actions may include implementation or adjustment of recreational and commercial fishing regulations.