The Effects of Global Warming on Wildlife

Polar Bear, Penguins and Seal on a Small Island of Ice

 

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Global warming, scientists say, is responsible not only for shrinking ice caps but also for a surge in extreme weather that is causing heat waves, forest fires, and droughts. The polar bear standing on a chunk of shrinking ice, apparently stranded, has become a familiar image, a symbol of the devastating effects of climate change.

This image is somewhat misleading since polar bears are powerful swimmers and climate change will primarily affect them by restricting access to prey. Nevertheless, researchers agree that even small changes in temperature are enough to threaten hundreds of already struggling animals. Time is of the essence: A 2003 study in the journal Nature concluded that 80 percent of some 1,500 wildlife species sampled are already showing signs of stress from climate change.

Habitat Disruption

The key impact of global warming on wildlife is habitat disruption, in which ecosystems—places where animals have spent millions of years adapting—rapidly transform in response to climate change, reducing their ability to fulfill the species' needs. Habitat disruptions are often due to changes in temperature and water availability, which affect the native vegetation and the animals that feed on it.

Affected wildlife populations can sometimes move into new spaces and continue to thrive. But concurrent human population growth means that many land areas that might be suitable for such “refugee wildlife” are fragmented and already cluttered with residential and industrial development. Cities and roads can act as obstacles, preventing plants and animals from moving into alternative habitats.

A report by the Pew Center for Global Climate Change suggests that creating “transitional habitats” or “corridors” could help migrating species by linking natural areas that are otherwise separated by human development.

Shifting Life Cycles

Beyond habitat displacement, many scientists agree that global warming is causing a shift in the timing of various natural cyclical events in the lives of animals. The study of these seasonal events is called phenology. Many birds have altered the timing of long-held migratory and reproductive routines to better sync up with the warming climate. And some hibernating animals are ending their slumbers earlier each year, perhaps due to warmer spring temperatures.

To make matters worse, research contradicts the long-held hypothesis that different species coexisting in a particular ecosystem respond to global warming as a single entity. Instead, different species within the same habitat are responding in dissimilar ways, tearing apart ecological communities millennia in the making.

Effects on Animals Affect People Too

As wildlife species struggle and go their separate ways, humans can also feel the impact. A World Wildlife Fund study found that a northern exodus from the United States to Canada by some types of warblers led to a spread of mountain pine beetles that destroy valuable balsam fir trees. Similarly, a northward migration of caterpillars in the Netherlands has eroded some forests there.

Which Animals Are Hardest Hit by Global Warming?

According to Defenders of Wildlife, some of the wildlife species hardest hit by global warming include caribou (reindeer), arctic foxes, toads, polar bears, penguins, gray wolves, tree swallows, painted turtles, and salmon. The group fears that unless we take decisive steps to reverse global warming, more and more species will join the list of wildlife populations pushed to the brink of extinction.