The study estimates that climate change projected to take place between now and the year 2050 will place 15 to 37 percent of all species in several biodiversity-rich regions at risk of extinction. The scientists believe there is a high likelihood of extinctions due to climate change in other regions, as well.
Scientists studied six regions around the world representing 20 percent of the planet's land area and projected the future distributions of 1,103 animal and plant species. Three different climate change scenarios were considered – minimal, mid-range and maximum, as was the ability of some species to successfully "disperse," or move to a different area, thus preventing climate change-induced extinction. The study used computer models to simulate the ways species' ranges are expected to move in response to changing temperatures and climate. It represents the largest collaboration of scientists to ever study this problem.
"This study makes it clear that climate change is the most significant new threat for extinctions this century," said co-author Lee Hannah, Climate Change Biology Senior Fellow at the Center for Applied Biodiversity Science (CABS) at Conservation International (CI). "The combination of increasing habitat loss, already recognized as the largest single threat to species, and climate change, is likely to devastate the ability of species to move and survive."
These forecasts are for species predicted to go extinct eventually based on climate change between now and 2050, but do not suggest that these species will go extinct by then.
The study concluded that the minimum expected, or inevitable, climate change scenarios for 2050 produce fewer projected extinctions (18% averaging across the different methods) than mid-range projections (24%), and about half those predicted under maximum expected climate change (35%). Therefore, 15-20% of all land species could be saved from extinction if the minimum scenario of climate warming occurs.
"If these projections are extrapolated globally and to other groups of land animals and plants, our analyses suggest that well over a million species could be threatened with extinction as a result of climate change," said study lead author Chris Thomas of the University of Leeds.
Small fluctuations in climate can affect a species' ability to remain in its original habitat. Slight increases in temperature can force a species to move toward its preferred, usually cooler, climate range. If development and habitat destruction have already altered those habitats, the species often have no safe haven. According to Hannah, this study underscores the need for a two-part conservation strategy.
"First, greenhouse gasses must be reduced dramatically, and a rapid switch to new, cleaner technologies could help save innumerable species," he said. "Second, we must design conservation strategies that recognize that climate change is going to affect entire ecosystems, and therefore have to prepare effective conservation measures immediately."
For this study, CABS at CI worked with the National Botanical Institute of South Africa to model more than 300 plant species in South Africa's Cape Floristic Region, located on the country's southern tip. In that region, fully 30 to 40 percent of South African Proteaceae, for example, is forecast to go extinct as a result of climate change between now and 2050. Proteaceae is a family of flowering plants that includes South Africa's national flower, the King Protea, as well as the daystar and the pincushions.
The Cape Floristic Region is considered one of the world's 25 "biodiversity hotspots," areas with a large number of unique species under tremendous threat.
Global mean temperatures have increased about one degree Fahrenheit over the past century with accelerated warming over the past two decades. Scientists attribute the recent rise of global temperature to human induced activities that have altered the chemical composition of the atmosphere. The buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide – traps heat, acting much like a greenhouse in the atmosphere.
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The Center For Applied Biodiversity Science (CABS) based at Conservation International, strengthens the ability of CI and other institutions to accurately identify and quickly respond to emerging threats to Earth's biological diversity. CABS brings together leading experts in science and technology to collect and interpret data about biodiversity, to develop strategic plans for conservation and to forge key partnerships in all sectors toward conservation goals. Read more about CABS at www.biodiversityscience.org.