The Heat Is Online

Species Redistribution Could Trigger Major Changes

Climate change will unbalance ecosystems, April 11, 2002

LONDON - Climate change over the next 50 years will throw delicate ecosystems off balance, reduce the geographical range of many species and bring new predators and prey together, scientists said yesterday.

Fewer species than expected will become extinct but their distribution could be radically different in the years to come which will have unpredictable results for humans.

"This is important because the modifications affecting our climate are like a big experiment the world is doing without knowing what's going to happen," said A. Townsend Peterson, of the University of Kansas Natural History Museum and Biodiversity Research Center.

Townsend and his Kansas colleagues and scientists in Mexico and California produced a new model of climate change based on an analysis of its impact on more than 1,800 species of mammals, birds and butterflies in Mexico.

The research, reported in the science journal Nature , could offer new insights and guidance to conservationists and policy makers.

The scientists used computer simulations to calculate how climate change will impact on individual species and where they will be likely to survive in the next half century.

"Deleting a species here and there will produce effects of unknown properties. We don't know what will happen when you delete five percent of the species and we were finding as high as 40 percent of species removed at times," Townsend said in a telephone interview.

"That is a scary result."

The scientists studied species in Mexico because of its biodiversity. The most worrying result was the reshuffling of ecological communities - species that live together.

They predicted the biggest disruption of ecosystems will probably be in the Chihuahua desert.

Townsend said each species shows an individual response to climate change which is complicated and that the rearrangement of ecological communities may be more serious than expected.

"If you remove enough species from an ecosystem, it's like the old child's game of pick-up sticks - there are only so many changes you can make before the ecosystem just rearranges, and maybe strikingly," Townsend added.