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James Hansen's Outlandish "Alpine Plant Extinction Claim" Is Debunked by Real-World Data
Scherrer, D. and Korner, C. 2010. Infra-red thermometry of alpine landscapes challenges climatic warming projections. Global Change Biology 16: 2602-2613.

The authors write that "climate warming scenarios predict higher than average warming in most alpine areas," and, therefore, that "alpine regions are often considered as particularly threatened." In fact, in testimony presented before the Select Committee of Energy Independence and Global Warming of the United States House of Representatives on 26 April 2007, NASA's James Hansen declared that life in alpine regions is in danger of being "pushed off the planet" as the earth warms, as it has "no place else to go." But is this really so?

What was done
In a study designed to test this very concept, Scherrer and Korner employed thermal imagery and microloggers to assess the fine-scale detail of both surface and root zone temperatures in three different temperate-alpine and subarctic-alpine regions: one in the Swiss Alps, one in North Sweden and one in North Norway, all of which study sites were located on steep mountain slopes above the climatic tree line and exhibited a rich microtopography but no change in macroexposure.

What was learned
The two Swiss scientists report that "microclimatic variation on clear sky days was strong within all slopes, with 8.4 2.5°C (mean SD) surface temperature differences persisting over several hours per day along horizontal (i.e., equal elevation) transects," which differences, as they describe them, "are larger than the temperature change predicted by the IPCC."

What it means
Scherrer and Korner say their findings are "important in the context of climate change," because they show that "species do not necessarily need to climb several hundred meters in elevation to escape the warmth." Quite often, in fact, they say that a "few meters of horizontal shift will do," so that for plants "unable or too slow to adapt to a warmer climate, thermal microhabitat mosaics offer both refuge habitats as well as stepping stones as atmospheric temperatures rise."

In discussing their results more broadly, the Swiss scientists state that their data "challenge the stereotype of particularly sensitive and vulnerable alpine biota with respect to climatic warming," noting that "high elevation terrain may in fact be more suitable to protect biodiversity under changing climatic conditions than most other, lower elevation types of landscapes." Thus, in what would appear to be a bit of good advice to all -- and James Hansen in particular -- the two researchers say they "advocate a more cautious treatment of this matter."

Reviewed 8 December 2010