Climate change is predicted to be one of the major causes of species extinction in the 21st century. The IUCN estimate that approximately 20 to 30 % of plant and animal species are likely to be at increasingly high risk as global mean temperatures rise. Species with the lowest capacity to adapt in regions expected to experience the highest level of climatic change face the greatest risk. Those thought to be particularly vulnerable include Arctic species, such as the Arctic fox, which is threatened by changes to the tundra habitat as the region warms. The warming climate is also encouraging the gradual northward encroachment of the red fox, a predator of Arctic foxes, as well as interrupting the breeding cycles of voles and lemmings, which constitute the main food sources for Arctic foxes.
Disrupted Breeding Patterns
In Britain climate change threatens biodiversity by disrupting breeding patterns for a number of species. As the climate changes there is already a marked impact upon the timings of seasonal change, with many species of plants coming into leaf and flower earlier in the year, as well as changes to the egg-laying dates of birds and timings of the emergence of moths and butterflies. The British Trust for Ornithology identified 39 bird species in a 2010 report that are laying eggs up to 30 days earlier than in the 1960s due to climate change. Because species adapt independently to changes in climate, these changing seasonal patterns may result in a mismatch in timing, such as between flowers and their insect pollinators, and between bird eggs hatching and the emergence of their insect prey. This has already been recorded for the golden plover and its food source the cranefly.
Geographical Distribution Of Species
Climate change also alters the geographical distribution of species through habitat loss and rising temperatures, with many species of birds, mammals, insects and plants moving further north. This northward shift threatens species unable to disperse easily due to fragmented landscapes and physical barriers such as land used for intensive farming. The black grouse is one example thought to be at risk of extinction due to climate change, which threatens the loss of suitable habitats with a climate similar to those they occupy today. Climate change also causes sea level rise, which could lead to the loss of coastal habitats where coastal developments prevent inland migration, as well as to the loss of freshwater habitats, such as wet grasslands that are important breeding sites for migratory birds. Some species of migratory birds may be lost to Britain altogether as temperatures rise, with the numbers of winter-visiting wading birds that breed in the Arctic already falling as warmer winter temperatures enable them to find suitable habitat further north. Climate change is also likely to increase the impact of invasive species by increasing the number of such species becoming established, as well as the spread of those currently limited to the south of England.
Climate change threatens biodiversity by leaving some species with literally nowhere to go.