Featured Research

from universities, journals, and other organizations

Western Canada's Glaciers Hit 7000-Year Low

Date:
November 1, 2007
Source:
Geological Society of America
Summary:
Tree stumps at the feet of Western Canadian glaciers are providing new insights into the accelerated rates at which the rivers of ice have been shrinking due to human-aided global warming. Scientists radiocarbon-dated wood from the newly visible stumps to see how long they have been in cold storage. The result was a surprising 7000 years.

Overlord Glacier has receded into the background of this image, leaving visible a stump that was remarkably well preserved in 7000 years old ice, bottom right.
Credit: Johannes Koch, image courtesy of Geological Society of America

Tree stumps at the feet of Western Canadian glaciers are providing new insights into the accelerated rates at which the rivers of ice have been shrinking due to human-aided global warming.

Related Articles


Geologist Johannes Koch of The College of Wooster found the deceptively fresh and intact tree stumps beside the retreating glaciers of Garibaldi Provincial Park, about 40 miles (60 km) north of Vancouver, British Columbia. What he wanted to know was how long ago the glaciers made their first forays into a long-lost forest to kill the trees and bury them under ice.

To find out, Koch radiocarbon-dated wood from the stumps to see how long they have been in cold storage. The result was a surprising 7000 years.

"The stumps were in very good condition sometimes with bark preserved," said Koch, who conducted the work as part of his doctoral thesis at Simon Fraser University in Burnaby, British Columbia. Koch will present his results on Wednesday, 31 October 2007, at the Geological Society of America Annual Meeting in Denver.

The pristine condition of the wood, he said, can best be explained by the stumps having spent all of the last seven millennia under tens to hundreds of meters of ice. All stumps were still rooted to their original soil and location.

"Thus they really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance," Koch explained. They also give us a span of time during which the glaciers have always been larger than they were 7000 years ago – until the recently warming climate released the stumps from their icy tombs.

Koch compared the kill dates of the trees in the southern and northern Coast Mountains of British Columbia and those in the mid- and southern Rocky Mountains in Canada to similar records from the Yukon Territory, the European Alps, New Zealand and South America. He also looked at the age of Oetzi, the prehistoric mummified alpine "Iceman" found at Niederjoch Glacier, and similarly well-preserved wood from glaciers and snowfields in Scandinavia.

The radiocarbon dates seem to be the same around the world, according to Koch. It's important to note that there have been many advances and retreats of these glaciers over the past 7000 years, but no retreats that have pushed them back so far upstream as to expose these trees.

The age of the tree stumps gives new emphasis to the well-documented "before" and "after" photographs of retreating glaciers during the 20th century.

"It seems like an unprecedented change in a short amount of time," Koch said. "From this work and many other studies looking at forcings of the climate system, one has to turn away from natural ones alone to explain this dramatic change of the past 150 years."


Story Source:

The above story is based on materials provided by Geological Society of America. Note: Materials may be edited for content and length.


Cite This Page:

Geological Society of America. "Western Canada's Glaciers Hit 7000-Year Low." ScienceDaily. ScienceDaily, 1 November 2007. <www.sciencedaily.com/releases/2007/10/071030092705.htm>.
Geological Society of America. (2007, November 1). Western Canada's Glaciers Hit 7000-Year Low. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2007/10/071030092705.htm
Geological Society of America. "Western Canada's Glaciers Hit 7000-Year Low." ScienceDaily. www.sciencedaily.com/releases/2007/10/071030092705.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Late Winter Storm Wreaks Havoc Across Eastern US

Late Winter Storm Wreaks Havoc Across Eastern US

AP (Mar. 5, 2015) — A strong cold front moving across the eastern U.S. has dumped deep snow in some regions, creating hazardous conditions from Kentucky to New England. (March 5) Video provided by AP
Powered by NewsLook.com
Keurig Co-Founder Says Company Has A Waste Problem

Keurig Co-Founder Says Company Has A Waste Problem

Newsy (Mar. 5, 2015) — Keurig co-founder John Sylvan told The Atlantic he doesn&apos;t even own a Keurig because they&apos;re too expensive and produce too much waste. Video provided by Newsy
Powered by NewsLook.com
Raw: Tourists Visit Rare Grey Whales in Mexico

Raw: Tourists Visit Rare Grey Whales in Mexico

AP (Mar. 4, 2015) — Once nearly extinct, grey whales now migrate in their thousands to Mexico&apos;s Vizcaino reserve in Baja California, in search of warmer waters to mate and give birth. Tourists flock to the reserve to see the whales, measuring up to 49 feet long. (March 4) Video provided by AP
Powered by NewsLook.com
Raw: Injured Miners Treated After Blast

Raw: Injured Miners Treated After Blast

AP (Mar. 4, 2015) — An explosion ripped through a coal mine before dawn Wednesday in war-torn eastern Ukraine, killing at least one miner, officials said. Graphic video of injured miners being treated in a Donetsk hospital. (March 4) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins