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.
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.
