Pikas, pygmy possums and tiny flowers in the high Swiss Alps are climate changes “canary in the coal mine,” signalling changes underway, according to a news piece in today’s Science by Kevin Krajick (sub. req.):

Alpine ecosystems are particularly vulnerable to climate change, and recent studies suggest that mountain dwellers–from delicate flowers in the Swiss Alps to pygmy possums in Australia–are in trouble. Although it can be difficult to tease out other factors, including fire suppression and livestock grazing, a growing number of researchers fear that if the heat keeps rising, many alpine plants and animals will face quick declines or extinction.

“People always thought the whole world could go to hell, and pikas would be fine. Actually, they may be canaries in the coal mine,” says wildlife biologist Andrew Smith of Arizona State University in Tempe.

The basic problem is that the critters up on the top of a mountain are trapped. You see these “island ecosystem” effects all the time, little isolated populations in high country. Where flatland plants and animals can in many cases drift north, south, east or west as their ecosystem home moves, high country critters can only go up. And if they’re already at the top of the mountain?

High-mountain biota are trapped, however, and those living in the alpine are in the tightest corner of all. Comprising just 3% of the vegetated terrestrial surface, these islands of tundra are Noah’s ark refuges where whole ecosystems, often left over from glacial times, are now stranded amid uncrossable seas of warm lowlands.

These islands are shrinking. The lowest elevation at which freezing occurs in mid-latitude mountains has climbed 150 meters since 1970. (On average, each rise of 100 meters in altitude corresponds to a 0.5?C drop in mean temperature.) This appears to be hastening local extinctions that have been proceeding slowly since the last glacial age. Fossils show that pikas, for example, once ranged widely over North America but have contracted to a dwindling number of high peaks during warm periods of the last 12,000 years, says U.S. Geological Survey (USGS) ecologist Erik Beever.