ScienceDaily (Nov. 17, 2009) — Increasing temperatures at high altitudes are fueling the post-1950 growth spurt seen in bristlecone pines, the world's oldest trees, according to new research.
Pines close to treeline have wider annual growth rings for the period from 1951 to 2000 than for the previous 3,700 years, reports a University of Arizona-led research team. Regional temperatures have increased, particularly at high elevations, during the same 50-year time period.
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Co-author Malcolm K. Hughes said, "Something very unusual is happening at high elevations, and this is one more piece of evidence for that." One other example, he said, was the accelerated melting of small glaciers at high altitudes.
"There is increasingly rapid warming in western North America," said Hughes, a UA Regents' Professor of dendrochronology. "The higher you go, the faster it's warming. We think our finding may be part of that whole phenomenon."
http://www.sciencedaily.com/releases/2009/11/091116163206.htm