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Extinctions
Tue Mar 02, 2004
Listen in RealAudio 
There has already been one animal extinction linked with climate change and if a recent report
is right, many, many more are bound to happen.
Hi, I'm Bryan Yeaton, and this is the Weather Notebook's weekly series on global climate
change.
The Golden Toad has disappeared from Costa Rica's central highlands, a victim of sudden
reductions in moisture levels there due to climate change. And hundreds of other plants and
animals are already changing where they live because global warming is altering their
habitat.
But now comes news that up to one million species could be on the path to extinction by the
year 2050. This prediction, which came in the journal Nature, found that if the planet warms
by about three and a half degrees Fahrenheit by 2050, a quarter of the world's plants and
animals will be extinct, or well on the way there.
Each species lives in a so-called "climate envelope," a habitat determined by temperature,
precipitation, and other factors. These climate envelopes change as the climate alters,
shifting species north or south, or higher or lower in elevation. But the number of species
that can live in a habitat is closely related to the size of that area. By changing climate
envelopes, some species get crowded out. Examining over a thousand species in six areas across
the globe, including Mexico, Australia, and Brazil, the scientists found it most likely that a
quarter of today's species will eventually get tossed out of their envelope.
The study's authors say climate change is now the biggest new extinction threat: a threat
multiplied by habitat loses taking place due to human development.
Thanks to David Appell for today's story. The Weather Notebook is produced by The Mount
Washington Observatory, with support from The National Science Foundation, and Subaru - Driven
by What's Inside. Find us on the web at www.weathernotebook.org.
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