Climate change impact: 11% of species extinct by 2100

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Human-caused climate change could become responsible for hundreds-of-thousands if not millions of species vanishing from the Earth

by Jeremy Hamce
Mongobay, July 11, 2011 

Scientists have predicted for decades that climate change could have a grave impact on life on Earth, which is already facing numerous threats from habitat loss, over-exploitation, pollution, invasive species, and other impacts. However, empirical proof of extinctions–and even endangerment–due to climate change have been difficult to come by.

A new study in the Proceeding of the National Academy of Science has found that by the time today’s infants are 90 years old (i.e. the year 2100) climate change could have pushed over 11 percent of the world’s species to extinction.

“Many scientists argue that we are entering the sixth great mass extinction and that anthropogenic climate change is one of the major threats to global biodiversity,” the researchers state.

Scouring recent studies, Ilya Maclean and Robert Wilson with the Center for Ecology and Conservation at the University of Exeter, found widespread evidence of over a hundred ways in which climate change is already impacting species, including rising temperatures, changes in rainfall, and decreased sea ice. They also noted a number of predicted, but not yet observed, ways in which scientists expect climate change to impact species.

“The responses included documented changes to extinction risk, population size, and geographic range size for 305 taxa from all major groups of organisms, covering a high proportion of the global terrestrial and marine surface,” the scientists write, adding that vertebrate species appear more threatened by climate change than plants and invertebrates.

However, the scientists admit there are big gaps in research to date.

“More studies on effects such as changes in oceanic circulation patterns and acidity on marine organisms would improve estimates of extinction risk,” they write. Species in the tropics, such as rainforest wildlife, and insects in general are also neglected in terms of the impact of climate change. The expected impact of climate change on the world’s species could shift with more research.

“There are many unknowns when projecting declines in biodiversity, and the values here should be interpreted with caution,” the researcher write, however they add that their data took into account a number of possible biases. Given the fact that climate change will impact species already under pressure from a number of other large-scale threats, the researchers say their estimate, if anything, is conservative.

But if their model is accurate, human-caused climate change could become responsible for hundreds-of-thousands if not millions of species vanishing from the Earth. Currently, around 2 million species have been described by scientists since the 18th Century, however no one knows just how many species call our planet their home. Estimates range from 5 million to a hundred million. Recent discoveries of wildly diverse and abundant microbe communities in the oceans could push the number even higher, possibly to a billion species.

CITATION: Ilya M. D. Maclean and Robert J. Wilson. Recent ecological responses to climate change support predictions of high extinction risk. PNAS.