Monday, August 11, 2008

Climate change caused widespread tree death in California mountain range, study confirms

Press release from the University of California at Irvine: Warmer temperatures and longer dry spells have killed thousands of trees and shrubs in a Southern California mountain range, pushing the plants’ habitat an average of 213 feet up the mountain over the past 30 years, a UC Irvine study has determined.

White fir and Jeffrey pine trees died at the lower altitudes of their growth range in the Santa Rosa Mountains, from 6,400 feet to as high as 7,200 feet in elevation, while California lilacs died between 4,000-4,800 feet. Almost all of the studied plants crept up the mountain a similar distance, countering the belief that slower-growing trees would move slower than faster-growing grasses and wildflowers.

This study is the first to show directly the impact of climate change on a mountainous ecosystem by physically studying the location of plants, and it shows what could occur globally if the Earth’s temperature continues to rise. The finding also has implications for forest management, as it rules out air pollution and fire suppression as main causes of plant death.

“Plants are dying out at the bottom of their ranges, and at the tops of their ranges they seem to be growing in and doing much better,” said Anne Kelly, lead author of the study and a graduate student in the Department of Earth System Science at UCI. “The only thing that could explain this happening across the entire face of the mountain would be a change in the local climate.”

The study appears online the week of Aug. 11 in the Proceedings of the National Academy of Sciences. Kelly and Michael Goulden, Earth system science professor, studied the north face of the Santa Rosa Mountains, just south of Palm Desert near Idyllwild, Calif. In the past 30 years, the average temperature there rose about 2 degrees Fahrenheit. While overall precipitation increased, the area experienced longer periods of drought, specifically in 1987-1990 and 1999-2002.

…“I was surprised by how nice the data looked and how unambiguous the signal was,” Goulden said. “It is clear that ecosystems can respond rather rapidly to climate change.” The scientists say air pollution did not kill the trees or cause the shift because the area does not have unusually high carbon dioxide levels, and they did not observe the characteristic speckling on plants caused by ozone damage. Also, if it was pollution, all of the plants would be suffering, not just the ones at the bottom of their range. Fire suppression also is not a culprit, they say. The fire regime there is normal, with the last major fire occurring in the 1940s….

White fir trees died in the 2002 drought, while neighboring Jeffrey pines survived at this elevation. Photo from UC Irvine website

1 comment:

Anonymous said...

Great article to show how the news can be easily spun to make "good news" appear to be " bad." Read the first paragraph and then read the last paragraph.

There's no doubt the planet can adjust to the natural
process (as can humanity), otherwise we wouldn't be here.

I have a friend who is a creationist, there's nothing I can show him to change his mind, "The Bible is God's Word, what I read there is truth."

(There's a scientific concensus, everything the consensus tells me is the truth.)

I ask him about fossils which date much older than 8 thousand years and he says, "God placed them their to tes
our faith."

(The early snows and cold summers are a direct result of global warming. ... All the experts agree on this. We only have a couple of years to act or the world will become unlivable.)

My creationist friend tells me, "We have suffering on the earth because we have sinned against God."

(Global warming exists because we have sinned against the Earth. Our only salvation is to atone for our sins by doing the "right thing."

A belief in something beyond yourself and in "original sin" is a central theme in most religions.