Polar species, including the polar bear, ice-dependent seals, and emperor penguins are especially vulnerable to the effects of climate change as their unique sea ice habitats shrink due to warming. Mountain species are at risk as warming shifts climates uphill and those living at the tops of mountains run out of suitable climate space. Corals and other species that depend upon them are also highly vulnerable due to the combined effects of warming ocean water, ocean acidification, and other human-caused stresses.
Up to 30 percent of plant and animal species could face extinction if the global average temperature rises more than roughly 3 to 5°C. Temperatures in this range could be reached in this century if emissions are not reduced. Many species have already shifted their ranges to higher latitudes and higher elevations over the past several decades. Spring has been arriving earlier, influencing the timing of bird and fish migration, egg laying, leaves appearing on trees, and spring planting for agriculture and forestry. The magnitude of these types of changes is expected to increase along with temperatures over this century.
Some species are already suffering due to warming. For example, the harlequin frog, golden toad, and an estimated two-thirds of the 110 or so other brightly- colored toad species once plentiful in the mountains of Costa Rica have vanished, with a pathogen outbreak tied to global warming believed to be a key factor in their extinction.
Looking ahead, many other species may not be able to adapt to the rapid rate of projected climate change. In addition, the effects of global warming and its associated disturbances (including floods, droughts, insects, and fires) will be compounded by pollution, resource exploitation, and habitat fragmentation, adding further challenges to species’ ability to adapt.