Global warming represents a profound and emerging threat to biodiversity around the world. As temperatures rise, many habitats for plants and animals will change sometimes depriving them of the homes and niches to which they have adapted. For example, monarch butterflies could lose their wintering habitats in the mountains of Mexico, and polar bears could be affected by the loss of marine life. Many species will not be able to migrate fast enough to keep up with shifting habitat ranges. As a result, many species will become extinct, and ecosystems around the world will become even more fragile.
Scientists have estimated that up to 60% of northern latitude habitats could be affected by global warming. Habitats throughout the United States, from the spruce and fir forests of Maine to the mangrove swamps of coastal Florida could be dramatically altered.
Many observers have pointed to a growing body of evidence that global warming is not only a result of human activities, but that it is already having an impact on species and habitats. According to the Natural Resources Defence Council of USA: