(ENS) WASHINGTON --
change could drive more than a quarter of all land animals and plants into extinction, a new study published January 8 has determined. The Earth's warming climate could extinguish the existence of more than one million species, the researchers estimate.
The largest collaboration of scientists to ever investigate this issue used computer models to simulate the ways species' ranges are expected to move in response to changing temperatures and climate. Their findings are published in today's edition of the journal "Nature."
"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 at Conservation International. "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."
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.
It is inevitable that at least 18 percent of all land plants and animals now on Earth will be on their way to extinction by 2050, the study finds, based on the climate changes that have already taken place.
But 15 to 20 percent of all land species could be saved from extinction if the minimum scenario of climate warming occurs.
For this study, scientists from the Center for Applied Biodiversity Science worked with their counterparts at 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, 30 to 40 percent of South African Proteaceae 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.
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.
In all, 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 Ð minimal, mid-range and maximum, as was the ability of some species to successfully "disperse," or move to a different area, preventing extinction caused by climate change.
The mid-range projection is that 24 percent of species will become extinct, and under maximum expected climate change, 35 percent of all land species will cease to exist.
"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.
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 2050.
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, the scientists explain. If development and habitat destruction have already altered those habitats, the species often have no safe haven.
Hannah says the findings underscore the need for a two part conservation strategy.
"First, greenhouse gases 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."
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 like a greenhouse in the atmosphere.
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