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South Florida
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Rising Seas, Changing Climate The broad, shallow river of grass that stretches south from Florida's Lake Okeechobee is the largest remaining subtropical wilderness in the continental United States. Everglades National Park is one of the crown jewels of the National Park Service. The only place in the world where alligators and crocodiles exist side by side, the park provides important habitat for a rich variety of wildlife, fish, and plants, as well as a freshwater source for south Florida's burgeoning human population.
The Everglades are home to some of the nation's most spectacular wild creatures, including the American crocodile, Florida panther, and West Indian manatee. The vast sloughs and sawgrass prairies provide crucial habitat for endangered birds such as the snail kite and wood stork, and threatened species such as the southern bald eagle, piping plover, and roseate tern.
Impacts at a Glance
- The Everglades and other south Florida ecosystems already are stressed by the pressures of human development. Global warming will add additional stresses, such as higher water levels, increased salinity, and warmer water temperatures.
- The sea along the Florida coast is rising 6-10 times faster than the average rate for that area over the past 3,000 years.
- Sea level in south Florida is likely to rise 20 inches above its 1990 level by the year 2100.
- Higher seas will make inland areas more susceptible to damage from storm surges during hurricanes.
- The freshwater Everglades are separated from Florida Bay by a wide ring of mangroves that act as a natural dike against the sea. The future survival of the Everglades depends in part on whether the mangroves can continue to keep pace with sea level rise.
- Warmer water could damage Florida's temperature-sensitive coral reef communities through a phenomenon known as coral bleaching.
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The Everglades also are a place apart, a natural area unlike any other in North America.
The 1.5 million-acre Everglades National Park has been designated an International Biosphere Reserve, a World Heritage Site, and a Wetlands of International Importance. As Marjory Stoneman Douglas wrote in 1947, "There are no other Everglades in the world. They are, they always have been, one of the unique regions of the Earth; remote, never wholly known."
In addition to the complex and fragile Everglades ecosystem, south Florida's abundant natural treasures include cypress swamps, mangrove forests, a highly productive estuary, coral reefs, and the Florida Keys. South Florida's natural areas provide visitors and residents with some of the nation's best fishing, diving, canoeing, camping, birding, and nature study opportunities.
But south Florida also faces severe environmental challenges. Florida has one of the fastest growing human populations in the United States, especially in the southern counties of Miami-Dade, Broward, and Palm Beach. Some 900 people move to Florida every day, with 39 million people vacationing in the state some years.
The Everglades have been called "the most endangered national park in the nation."
Water management systems for flood control, agriculture, and urban water supplies have dramatically altered freshwater flow through the River of Grass, with repercussions throughout the ecosystem. For example, the draining of the Everglades caused wood stork populations to decline by almost 95 percent from the 1870s to the 1970s. The reduced water flow has allowed saltwater to penetrate inland, contaminating freshwater aquifers, and agricultural runoff has polluted the water with phosphorus and other excess nutrients. With less freshwater flowing into Florida Bay, the bay has become saltier.
The increasing salinity affects life in the bay and may harm coral reefs near the cuts where bay water flows to the ocean through the Florida Keys.
"The Everglades is a test. If we pass, we get to keep the planet."
- Joe Podgor, Former Executive Director, Friends of the Everglades |
Federal and state programs are underway to restore freshwater flow to the Everglades and to prevent further damage to the ecosystem. But some scientists are concerned that these efforts may not save the Everglades in the long term. These scientists recognize that the Everglades and south Florida are vulnerable to a very different threat emerging on the horizon: the rapidly rising seas and climatic changes associated with global warming.
Higher seas already are affecting the Florida coastline, and scientists expect the changes to accelerate in the decades ahead.
Visitors to the observation tower at Shark Valley in the year 2050 or 2075 might behold a very different landscape from the one they see today. University of Miami geologist Harold Wanless speculates that instead of today's River of Grass dotted with tree islands, the view from the tower might be one of mangrove-lined creeks and shallow saltwater or brackish ponds. The once-plentiful alligators and deer might be a rare sight at Shark Valley, many of them having moved inland to find better habitat with fresher water. Along the Wilderness Waterway, a popular canoe route that runs along the western side of the Everglades, campsites and chickees (elevated camping shelters) could be flooded with saltwater.
The effects of future sea level rise on the Everglades are uncertain. The freshwater Everglades are separated from the sea by a broad ring of mangroves. The mangroves' roots trap sediments, building thick layers of peat that have created a wide, low dike against the sea. If this natural barrier can continue to grow vertically in pace with sea level rise, the Everglades may be relatively unaffected by the rising tide. But if the sea rises faster than the mangroves, or if large tracts of mangrove forest are damaged by hurricanes and fail to recover, much of the freshwater Everglades might disappear during the next 100 years, replaced by saltwater wetlands and shallow bays.
Scientists do not know which is the more likely scenario. In the face of such uncertainty, many environmentalists and policymakers believe we should "hope for the best but plan for the worst," and take precautionary action to slow global warming and sea level rise.
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