Ecology and the Environment

How does global warming affect ecosystems?
Answered by Susan Sherwood and Discovery Channel
  • Susan Sherwood

    Susan Sherwood

  • Discovery Channel

    Discovery Channel

  1. "Ecosystem" refers to the relationships among living things and their environment within a specific area. We could discuss the ecosystem of an entire forest or focus on the ecosystem of one dead tree. Therefore, as temperatures rise, effects are going to vary depending upon the system. Let's look at two specific regions to see what could be in store.

    Florida is already feeling the impact of global warming; its average temperature has increased two degrees Fahrenheit, and the yearly number of above-90-degree days is expected to almost triple by the end of the century (to about 165 days).  One consequence could be a rise in the number of insects, accompanied by their voracious appetites (goodbye, plants) and their vector diseases (hello, dengue fever) [source: Barclay]. The state will not just get hotter; it'll also get wetter.

    If human contributions to greenhouse gas emissions are not controlled, sea level is projected to rise at least three feet within the next 100 years, a result of melting polar ice caps. Coastal areas would be underwater; some Florida Keys islands would be entirely submerged. Florida's beach, mangrove and wetland habitats would essentially disappear, along with their flora and fauna. Inland plants and animals would feel the effects of salt water encroaching on the Everglades wetlands and freshwater rivers.

    The Florida Keys are home to an enormous coral reef that is already being injured by increasing water temperature, which bleaches the reef of color. Global warming also causes higher levels of carbon dioxide in the water; this could restrain the growth and development of the reef, severely impacting one of Florida's most-visited areas. A decrease in tourism would result in a drop in the state's economy.

    New England has faced similar temperature increases. Average temperatures may increase more than 10 degrees Fahrenheit by the end of the century, affecting seasonal changes. Winters would be shorter, spring and summer longer and autumn less cold and rainy. This would diminish the normally spectacular New England fall foliage.  There could be a decrease in tree diversity, including the loss of maple, spruce and fir species.

    Increasing ocean temperatures are already harming New England's cod and lobster industries by decreasing the harvest. The availability of freshwater fish may also be affected as rising temperatures cause inland waters to dry up.

    This glimpse at two coastal locations barely touches on potential global warming effects worldwide.


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  2. A small shift in climate can affect living ecosystems. Some plants and animals would adapt to the change or move, but many species would be killed off. Since ecosystems are connected, changes in climate could cause a chain reaction, killing off species that depend on each other. Changes in average temperatures could also affect growing seasons and precipitation amounts, depending on whether the area is more or less temperate. An Intergovernmental Panel on Climate Change report estimates that about 20 percent to 30 percent of plant and animal species around the world may be at increased risk of extinction because global mean temperatures continue to rise more than 2 to 3 degrees Celsius above their levels before industrialization [source: U.S. Fish and Wildlife Service].

    Accelerated global warming is not limited to effects on climate and rainforests. Evidence continues to mount showing that climate change is having a number of damaging effects on wildlife habitats and populations. Canada has reported declining polar bear populations and across the United States, scientists have noted changes in birds' migratory patterns [source: U.S. Fish and Wildlife Service]. Higher water temperatures are affecting U.S. cold-water fish populations as well. Climate change is directly affecting wildlife that many people rely on for sport, including:

    • Big game: Increasing temperatures are allowing more disease-infected parasites to survive cold weather and infect herds of moose, elk and other big game animals. In addition, too much carbon dioxide exposure reduces a plant's nutritional value. Herds can starve from malnutrition even though they seem to have enough vegetation to eat.
    • Fish: Rising sea levels are destroying the breeding grounds of many fish species, resulting in declining populations. Some of the areas that will be most affected by this are the Mississippi Delta and the Florida Keys.
    • Birds: Some scientists are projecting that the number of bird species could drop by 30 percent if warming continues. Drought and rising sea levels are destroying the habitats of many species of birds, resulting in dramatic population declines.


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