The 2,000-year-old giant sequoias east of Fresno have survived warm spells lasting centuries, but in just 100 years, global warming could snuff them out -- along with many Sierra Nevada species. Why? The current episode of climate change is moving faster than any warm-up detected in the past 500,000 years, many scientists say. Many say car exhaust and other global-warming emissions from human activities may be the reason.
The rising temperatures probably will shorten the Sierra's long, snowy winters and force mass uphill migrations by sequoias, Sierra bighorn sheep, dusky woodrats, rabbitlike pikas and mountain yellow-legged frogs, scientists say. The warming could mean oblivion for those that can't cope.
"I avoid being an alarmist," said Nathan Stephenson, a U.S. Geological Survey research ecologist at the agency's Sequoia National Park field station. "But there's a chance sequoias won't survive at all if they can't find the right soil conditions at higher elevations."
The bighorn sheep, another mountain icon, might be forced to move uphill away from predators, perhaps marooning themselves on alpine islands away from their food sources, according to scientists. No one knows what will become of the small, hearty shrubs and animals above 11,000 feet if the Sierra's small glaciers disappear. Glacial ice has dripped precious water into an arid alpine landscape for thousands of summers, but it may last only a few more decades, scientists say. The warming also probably will force pines and firs to move uphill, along with vast communities of shrubs, herbs and grasses that support wildlife and help purify California's air.
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