Thu, Dec 15, 2011 - Page 15 News List

Naughty lemmings skew climate calculus

This NASA image released Nov. 15 shows massive cloudbank sprawled over central Europe in early November, with clouds extending from the North Sea to the foothills of the Alps.

Photo: AFP

Really, it is enough to drive a climate scientist over the edge.

In past years, satellite images have shown a perceptible growth in grasses and shrubs in parts of the Arctic, a phenomenon pinned on global warming. But part of the greening could come from lemmings, surprised researchers have found.

University of Texas scientists counted plant cover and biomass in a huge area in coastal Alaska where brown lemmings (Lemmus trimucronatus) have been monitored for more than 50 years in a project to understand their boom-and-bust population cycles.

On small plots that had been fenced off to exclude the lemmings, certain plant types called lichens and bryophytes had increased, the researchers found.

But where the lemmings scampered unhampered, there was an increase in grass and sedge — curiously, the very same plants that the hamster-like herbivores feed on.

The reason for this is unclear. Urine and feces from the lemmings could be acting as a fertilizer, helping the plants to grow, the researchers suggest.

Alternatively, the rodents could be chomping on the dead grass and sedge litter, which encourages new growth.

Either way, the findings pose a tundra conundrum. “We really need to be careful attributing the greening of the Arctic to global warming alone,” said the lead investigator, David Johnson.










1. pin on v. phr.

歸因於;怪罪於 (gui1 yin1 yu2; guai4 zui4 yu2)

例: You can’t pin the blame on her. She wasn’t even there when the accident happened.


2. boom-and-bust adj.

起落的;榮枯循環的 (qi3 luo4 de5; rong2 ku1 xun2 huan2 de5)

例: In the gold industry, boom-and-bust cycles last an average of 10 years.


3. conundrum n.

難題 (nan2 ti2)

例: Arranging childcare over the school holidays can be quite a conundrum for working parents.




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