Climate change assumption could need tinkering, study finds
A common assumption in models that game out what a warming planet will mean for plants and trees presumes they would migrate upward toward cooler mountain temperatures, such as the snowy peaks of California's Sierra Nevada. That has sparked concern that some species may die off when they cannot migrate higher.
It turns out that decades of old and new data show that many Sierra species have tended to migrate downhill over many decades, largely because of higher precipitation levels in central and northern California. It's unclear whether that wetter trend is part of a natural cycle or itself a result of a slowly warming planet. Some models predict parts of California will get wetter as the atmosphere warms because of the accumulation of greenhouse gases from human activity.
Times Staff Writer Bettina Boxall highlights the findings, part of a study appearing in the Jan. 21 issue of Science.
-- Geoff Mohan
Photo: Early 20th Century image taken as part of a U.S. Forest Service survey of California flora. Credit: The Wieslander Vegetation Type Mapping Collection, courtesy of the
Marian Koshland Bioscience on Natural Resources Library, UC Berkeley.