Global warming has already caused extinctions in the most sensitive habitats and will continue to cause more species to go extinct over the next 50 to 100 years, confirms the most comprehensive study since 2003 on the effects of climate change on wild species worldwide by a University of Texas at Austin biologist.
Dr. Camille Parmesan鈥檚 synthesis also shows that species are not evolving fast enough to prevent extinction.
鈥淭his is absolutely the most comprehensive synthesis of the impact of climate change on species to date,鈥� said Parmesan, associate professor of integrative biology. 鈥淓arlier synthesis were hampered from drawing broad conclusions by the relative lack of studies. Because there are now so many papers on this subject, we can start pulling together some patterns that we weren鈥檛 able to before.鈥�
Parmesan reviewed more than 800 scientific studies on the effects of human-induced climate change on thousands of species.
鈥淲e are seeing stronger responses in species in areas with very cold-adapted species that have had strong warming trends, like Antarctica and the Artic,鈥� said Parmesan. 鈥淭hat鈥檚 something we expected a few years ago but didn鈥檛 quite have the data to compare regions.鈥�
Previously published predictions, including those co-authored by Parmesan in a 2001 Intergovernmental Panel on Climate Change report, were that species restricted to cold climate habitats like the Earth鈥檚 poles or mountain tops and with narrow temperature tolerances (for example, tropical corals) would be most affected by global warming. Less than a decade later, those predictions have been born out.
The most sensitive species are going extinct and/or shifting their ranges geographically as their original habitats become inhospitable. The studies reviewed by Parmesan reveal this trend will continue.
鈥淪ome species that are adapted to a wide array of environments-globally common, or what we call weedy or urban species-will be most likely to persist,鈥� said Parmesan. 鈥淩are species that live in fragile or extreme habitats are already being affected, and we expect that to continue.鈥�
The studies Parmesan analyzed also show that some species鈥攖hose with short generation times like insects鈥攁re evolving in response to climate change, but not in ways that could prevent extinction.
鈥淪ome populations are adapting, but species are not evolving anything that鈥檚 really new, something we haven鈥檛 been able to say before because we didn鈥檛 have enough studies,鈥� Parmesan said. 鈥淭o really come up with something new that鈥檚 going to allow a species to live in a completely new environment takes a million years. It鈥檚 not going to happen in a hundred years or even a few hundred years. By then, we might not even think of it as the same species.
鈥淭he good news is that some species already had a few individuals that were good at moving, so some populations are evolving better dispersal abilities. These species are able to move faster and better than we thought they could as climate warms at their northern range boundaries. So, they鈥檙e expanding into new territories very rapidly.鈥�
Parmesan said that pests and diseases are also showing the same northward shifts as other wild animals.
Parmesan also found that, at present, scientists cannot predict exactly which species will respond to climate change based on what kind of organism it is. Within groups of animals and plants, some species respond to climate change and others do not.
鈥淲hether it鈥檚 within fish, trees or butterflies, you鈥檙e seeing some species responding strongly and some staying fairly stable,鈥� said Parmesan. 鈥淏ut within each group you鈥檙e still seeing about half of the species showing a response. It鈥檚 a very widespread phenomenon.鈥�
Parmesan鈥檚 review is published online in the Annual Review of Ecology, Evolution, and Systematics and is scheduled to appear in the print version of the journal this December.
Source: University of Texas at Austin
