Rewriting Glacial History In Pacific North America

January 11, 2006

Although the story on glacier fluctuations in northwestern North America over the last 10,000 years has remained largely unchanged for decades, new evidence discovered by a University of Alberta researcher will rewrite that glacial history and offer clues about our climate history during the last several thousand years.

Glacier fluctuations are sensitive indicators of past climate change, yet little is known about glacier activity in Pacific North America during the first millennium A.D. Alberto Reyes, a PhD student in the Department of Earth and Atmospheric Sciences, and his research team have found evidence for a regionally-extensive glacier expansion in the first millennium AD, suggesting that climate during the last several thousand years may have been even more variable than previously thought. The research appears in the journal Geology.

Reyes and his collaborators--the main ones were Dr. Dan Smith from the University of Victoria and Dr. Greg Wiles from the College of Wooster in Ohio--looked for a variety of clues in the field to help figure out the timing of past glacier fluctuations. At almost all of the glaciers studied, surface evidence prior to the "Little Ice Age" had been destroyed because glacial advance during that time had been so dramatic.

Most of the evidence they found was in the form of buried soils and logs covered by glacial sediments. "In some cases, entire forest stands were buried by sediments and their trunks sheared off by advancing ice," said Reyes, who initiated the work while a master's student at Simon Fraser University.

Samples were then sent off for radiocarbon dating and when the results came back, the researchers were able to tell a story about when each individual glacier was expanding. Reyes had earlier noted the first millennium AD glacier advance at the glacier he was studying for his master's thesis, which jumped out because it was not thought that glaciers in the region were expanding at that time.

After pouring over old data and early results of new research, the team found that many other glaciers had advanced during that period. "If only one or two glaciers are advancing at any particular time it is not really significant," said Reyes. "But when many glaciers across a wide region are advancing with some degree of synchronicity, there is likely something going on with regional climate that causes the glaciers to advance."

Reyes was surprised that the regional nature of this first millennium AD glacier advance remained unrecognized for so long. He suspects some of the earlier reports that hinted at the existence of an advance stayed under the radar because they did not fit into the established chronology of past glacier activity.

The glacier data reported by Reyes and colleagues, together with other clues of past climate, support an emerging idea that climate in the North Pacific region has cycled from warmer to colder intervals several times over the last 10,000 years.

Copyright 2006 by Space Daily, Distributed United Press International

Explore further: Preserving the memory of glaciers

Related Stories

Preserving the memory of glaciers

March 19, 2017

Locked up in about 140 metres (460 feet) of ice capping a Bolivian mountain lie 18,000 years of climate history, dating back to an epoch when humans were only just learning to farm.

The science of carbon dioxide and climate

March 13, 2017

The vast majority of scientists around the world agree that our climate is changing at a faster rate than ever recorded in human history because of our use of fuels such as coal and oil, so-called fossil fuels.

Warming ponds could accelerate climate change

February 20, 2017

Rising temperatures could accelerate climate change by reducing the amount of carbon dioxide stored in ponds and increasing the methane they release, new research shows.

Recommended for you

Study into who is least afraid of death

March 24, 2017

A new study examines all robust, available data on how fearful we are of what happens once we shuffle off this mortal coil. They find that atheists are among those least afraid of dying... and, perhaps not surprisingly, ...

Controlling ice formation

March 24, 2017

(Phys.org)—Researchers have demonstrated that ice crystals will grow along straight lines in a controlled way on microgrooved surfaces. Compared to the random formation of ice crystals on smooth surfaces, the ice on the ...

Astronomers identify purest, most massive brown dwarf

March 24, 2017

An international team of astronomers has identified a record breaking brown dwarf (a star too small for nuclear fusion) with the 'purest' composition and the highest mass yet known. The object, known as SDSS J0104+1535, is ...

Inventing a new kind of matter

March 24, 2017

Imagine a liquid that could move on its own. No need for human effort or the pull of gravity. You could put it in a container flat on a table, not touch it in any way, and it would still flow.

In a quantum race everyone is both a winner and a loser

March 24, 2017

Our understanding of the world is mostly built on basic perceptions, such as that events follow each other in a well-defined order. Such definite orders are required in the macroscopic world, for which the laws of classical ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.