The effect of Earth's changing climate -- due to warming from so-called greenhouse gases and other factors -- on natural ecosystems may be felt by species most at risk for reduced range or even extinction. A team of researchers supported by the National Science Foundation (NSF) and affiliated with the University of Kansas Natural History Museum and other institutions has reported on the first analysis of the potential impacts of climate change on species in an entire country, Mexico. The team's paper is published in this week's Nature.
"This research predicts that global climate change will cause substantial changes in the distribution of Mexican bird, mammal, and butterfly species," says Carol Johnston, program director in NSF's division of environmental biology, which funded the research.
The research, led by Townsend Peterson of the University of Kansas Natural History Museum, found that the changing climate is predicted to bring about great instability. "In some local communities more than 40 percent of species are expected to turn over, which will lead to a cascade of further effects," said Peterson, lead author of the Nature paper. "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 collapses on you."
"This research marks a major step forward in being able to investigate in a quantitative way the initial impacts of climate change on ecosystems and biodiversity," said Peterson. "This is important because the modifications affecting our climate are like a big experiment the whole world is doing without knowing what's going to happen."
For example, the west Mexican chachalaca, a bird found only in tropical southwestern Mexico, may be greatly affected by changing climate. Under some climate change scenarios, the species' distribution area in interior Mexico would become much less habitable, while its coastal range would remain intact. A narrow band of habitat in the foothills of the coastal mountain ranges might become more habitable.
The Nature article outlines research that not only looks at a great many species across a whole community but also examines them one-by-one, using realistic assumptions about their ability to change where they live in response to climate change. "That species-by-species look has allowed us to appreciate just how big the differences are in the way each species can respond to climate change," said Peterson.
"What we found is that the impacts aren't uniform, and the strongest effects turned out to be in the central Chihuahuan desert, south of New Mexico," he said. In that desert area, the researchers expect the greatest species turnover and disruption of ecosystems, which will unleash a complex chain of consequences that are difficult to foresee in detail but will be highly disruptive to ecosystems and certain species in particular.
Previous research has looked in a broad-brush way at how climate change would affect an ecosystem. For example, if a warmer climate will cause a given habitat to move northward, researchers made the assumption that the various species would simply move along with the ecosystem. Other detailed studies have been limited to looking at only a few species. "What's unique about what we've done is that for the first time we were able to look at a whole community in detail," said Peterson. His colleagues are affiliated with the Universidad Nacional Autonoma de Mexico and the San Diego Supercomputer Center.
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