Ancient trees give clues to climate change

[Judi Lynn]

Ancient trees give clues to climate change
Thu Feb 7, 2008 8:52pm EST

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Lake Nahuel Huapi is seen in this April 12, 2001 file photo.

REUTERS/Stringer/Files


By Kylie Stott

PUERTO BLEST, Argentina (Reuters) - On the shores of lake Nahuel Huapi, in the wild mountains of Argentina's Patagonia, live some of the world's most ancient trees.

Known in Spanish as the alerce, the Patagonian cypress grows extremely slowly, but can reach heights over 50 meters (165 feet) and live for 2,000 years or more, putting some of them among the oldest living things on earth.

For scientists who come from around the world to study them, the alerces give an exciting snapshot of years past.

Argentine geoscientist Ricardo Villalba, a contributor to the Nobel Prize-winning United Nations report on climate change last year, studies what the ancient trees say about changing weather patterns.

More:
http://www.reuters.com/article/environmentNews/idUSGOR80653320080208?feedType=RSS&feedName=environmentNews

[Lasher]

1. Related article in National Geographic this month

Drying of the West
The American West was won by water management. What happens when there's no water left to manage?

When provided with continuous nourishment, trees, like people, grow complacent.

Tree-ring scientists use the word to describe trees like those on the floor of the Colorado River Valley, whose roots tap into thick reservoirs of moist soil. Complacent trees aren't much use for learning about climate history, because they pack on wide new rings of wood even in dry years. To find trees that feel the same climatic pulses as the river, trees whose rings widen and narrow from year to year with the river itself, scientists have to climb up the steep, rocky slopes above the valley and look for gnarled, ugly trees, the kind that loggers ignore. For some reason such "sensitive" trees seem to live longer than the complacent ones. "Maybe you can get too much of a good thing," says Dave Meko.

<snip>

In fact, the tree rings testified that in the centuries before Europeans settled the Southwest, the Colorado basin repeatedly experienced droughts more severe and protracted than any since then. During one 13-year megadrought in the 12th century, the flow in the river averaged around 12 million acre-feet, 80 percent of the average flow during the 20th century and considerably less than is taken out of it for human use today. Such a flow today would mean serious shortages, and serious water wars. "The Colorado River at 12 million acre-feet would be real ugly," says one water manager.

Unfortunately, global warming could make things even uglier. Last April, a month before Meko and Woodhouse published their latest results, a comprehensive study of climate models reported in Science predicted the Southwest's gradual descent into persistent Dust Bowl conditions by mid-century. Researchers at the National Oceanic and Atmospheric Administration (NOAA), meanwhile, have used some of the same models to project Colorado streamflow. In their simulations, which have been confirmed by others, the river never emerges from the current drought. Before mid-century, its flow falls to seven million acre-feet—around half the amount consumed today.

http://ngm.nationalgeographic.com/ngm/2008-02/drying-west/kunzig-text.html