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"Warmed Fuzzies" -- The Discovery Files

The Discovery Files
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The balance of biodiversity within North American small-mammal communities is off balance from the last episode of global warming about 12,000 years ago that future climate change could push them past a tipping point, with repercussions up and down the food chain, say Stanford University biologists.

Credit: NSF/Karson Productions

Audio Transcript:

There are no Small Parts -- Only Small Animals.

I'm Bob Karson with the discovery files -- new advances in science and engineering from the National Science Foundation.

The extinction of species -- an obvious impact of the earth's last episode with global warming about 12,000 years ago. Larger animals like mastodons, dire wolves and short-faced bears all vanished. But a study led by Stanford biologists focused instead on nature's 'bit' players, smaller mammals who survived that warming. Some of them, like the deer mouse, actually thrived, while others took a huge hit. All of which destabilized food chains and ecosystems.

(Sound effect: cave excavation sounds) The team excavated fossil specimens from Samwell Cave in the foothills of the southern Cascade Mountains. The biologists were able to study not only the end of the pleistocene period when the warming occurred, but effects on the ecosystem in the 10,000 years since then even how animal populations are faring in the area today.

What they found was the earlier warming affected the balance and diversity of these small mammals. Some were driven close to the tipping point of extinction. They may not survive a second episode. Back in the day, the numbers of small animals were more evenly distributed each with a role to play in the ecosystem.

Up and down the food chain, the populations of small mammals have not fully recovered. And expected temperature change over the next hundred years may well be greater than anything these species have ever experienced.

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