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Climate change extinction risk 'greatly underestimated'

By Adrian Bishop - 04 Jan 2012 18:33:0 GMT
Climate change extinction risk 'greatly underestimated'

Alaskan ice cave, Valdez glacier via Shutterstock

Climate change could cause many more animal and plant extinctions than previously thought, ecologists say. Most previous climate change modelling has not taken into account the movement and competition among species, a new study claims.

Assistant Professor Mark Urban, from the University of Connecticut, who headed-up the report, says, "We have really sophisticated meteorological models for predicting climate change, but in real life, animals move around, they compete, they parasitize each other and they eat each other. The majority of our predictions don't include these important interactions."

Many studies show that species do move because of climate change, such as when temperatures rise, animals and plants move to higher ground to escape from the heat, says Assistant Professor Urban.

What they may not take into account is that species may die off before accessing improved habitat or may lose out to rival species already there or who have arrived previously.

University of Connecticut Assistant Professor Mark Urban stands under a sheet of aufeis in Alaska. These ice sheets form over Arctic underground springs but have become less prevalent with global warming. Urban, a professor of ecology and evolutionary biology, fears that current climate change models may grossly underestimate future extinctions because they fail to account for species competition and movement

University of Connecticut Assistant Professor Mark Urban stands under a sheet of aufeis in Alaska. These ice sheets form over Arctic underground springs but have become less prevalent with global warming. Urban, a professor of ecology and evolutionary biology, fears that current climate change models may grossly underestimate future extinctions because they fail to account for species competition and movement. Credit: Mark Urban

Assistant Professor Urban, along with Kimberly Sheldon and Josh Tewksbury, from the University of Washington, have devised a model that predicts how successful species might be when moving to new habitats, by including migration and competition factors.

Species that are flexible enough to adapt to climate change will have a better chance of survival, they have found.

Those who are not able to move far or need specific habitats or requirements are more likely to die off, according to the modelling.

Assistant Professor Urban explains, "When a species has a small range, it's more likely to be out competed by others. It's not about how fast you can move, but how fast you move relative to your competitors."

He illustrates the problem by comparing it to a mountain train, where each carriage represents a species. If all carriages move at the same speed, they reach the top at the same time. But if they could each travel at different speeds, there would be chaos.

"There's always a car in front of you and a car behind. When you introduce the ability to move at different speeds, they're constantly bumping into one another, even running each other over. It's a recipe for disaster."

All this means that many estimations of species loss due to climate change, could greatly underestimate levels of extinction.

Those in tropical areas that have great diversity of species in a small area are likely to be most at risk from climate change, he argues.

"This a first step - to include in our models things that we know are true, like competition and dispersal. Knowing these things, can we predict which species might be most at risk?"

The paper is being published online in the 4 January issue of Proceedings of the Royal Society B: Biological Sciences.

The study was financed by the National Science Foundation, which is an independent American federal agency, created to promote science, national health, prosperity and wealth and secure defence. Its total annual budget is around $7 billion (£4.5 billion).

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