Featured Research

from universities, journals, and other organizations

Long-lost Lake Agassiz offers clues to climate change

Date:
October 11, 2011
Source:
University of Cincinnati
Summary:
What caused water levels to drop in immense yet long-vanished Lake Agassiz? New research suggests that conditions 12,000 years ago encouraged evaporation. Not long ago, geologically speaking, a now-vanished lake covered a huge expanse of today's Canadian prairie. Although Lake Agassiz is gone, questions about its origin and disappearance remain. Answers to those questions may provide clues to our future climate.

Lowell extracts information from core samples in his University of Cincinnati laboratory.
Credit: Photo by Lisa Ventre

What caused water levels to drop in an immense yet long-vanished lake? Research by a University of Cincinnati geologist suggests that conditions 12,000 years ago encouraged evaporation.

Related Articles


Not long ago, geologically speaking, a now-vanished lake covered a huge expanse of today's Canadian prairie. As big as Hudson Bay, the lake was fed by melting glaciers as they receded at the end of the last ice age. At its largest, Glacial Lake Agassiz, as it is known, covered most of the Canadian province of Manitoba, plus a good part of western Ontario. A southern arm straddled the Minnesota-North Dakota border.

Not far from the ancient shore of Lake Agassiz, University of Cincinnati Professor of Geology Thomas Lowell will present a paper about the lake to the Geological Society of America annual meeting in Minneapolis. Lowell's paper is one of 14 to be presented Oct. 10 in a session titled: "Glacial Lake Agassiz -- Its History and Influence on North America and on Global Systems: In Honor of James T. Teller."

Although Lake Agassiz is gone, questions about its origin and disappearance remain. Answers to those questions may provide clues to our future climate. One question involves Lake Agassiz' role in a thousand-year cold snap known as the Younger Dryas.

As the last ice age ended, thousands of years of warming temperatures were interrupted by an abrupt shift to cold. Tundra conditions expanded southward, to cover the land exposed as the forests retreated. This colder climate is marked in the fossil record by a flowering plant known as Dryas, which gives the period its name.

"My work focuses on abrupt or rapid climate change," Lowell said. "The Younger Dryas offers an opportunity to study such change. The climate then went from warming to cooling very rapidly, in less than 30 years or so."

Scientists noted that the Younger Dryas cold spell seemed to coincide with lower water levels in Lake Agassiz. Had the lake drained? And, if so, had the fresh water of the lake caused this climate change by disrupting ocean currents? This is the view of many scientists, Lowell said.

Lowell investigated a long-standing mystery involving Lake Agassiz -- a significant drop in water level known as the Moorhead Low. It has long been believed that the Moorehead Low when water drained from Lake Agassiz through a new drainage pathway. Could this drainage have flowed through the St. Lawrence Seaway into the North Atlantic Ocean?

"The most common hypothesis for catastrophic lowering is a change in drainage pathways," Lowell said.

The problem is, better dating of lake levels and associated organic materials do not support a rapid outflow at the right time.

"An alternative explanation is needed," he said.

Lowell's research shows that, although water levels did drop, the surface area of the lake increased more than seven-fold at the same time. His research suggests that the lower water levels were caused by increased evaporation, not outflow. While the melting glacier produced a lot of water, Lowell notes that the Moorhead Low was roughly contemporaneous with the Younger Dryas cold interval, when the atmosphere was drier and there was increased solar radiation.

"The dry air would reduce rainfall and enhance evaporation," Lowell said. "The cold would reduce meltwater production, and shortwave radiation would enhance evaporation when the lake was not frozen and sublimation when the lake was ice-covered."

Further research will attempt a clearer picture of this ancient episode, but researchers will have to incorporate various factors including humidity, yearly duration of lake ice, annual temperature, and a better understanding of how and where meltwater flowed from the receding glaciers.

Lowell's efforts to understand changes in ancient climates have taken him from Alaska to Peru, throughout northern Canada and Greenland.

In Greenland, Lowell and a team of graduate students pulled cores of sediment from lakes that are still ice-covered for most of the year. Buried in those sediments are clues to long-ago climate.

"We look at the mineralogy of the sediments," Lowell said, "and also the chironomids. They're a type of midge and they're very temperature sensitive. The exact species and the abundance of midges in our cores can help pinpoint temperature when these sediments were deposited."

Lowell's research was initially funded by the Comer Foundation. In recent years, the National Science Foundation has provided funding for this work.

When the Geological Society of America meets this year the University of Cincinnati will be well represented, with more than two dozen papers and presentations. Topics range from ice-age climate to the health effects of corrosion in drinking water pipes.


Story Source:

The above story is based on materials provided by University of Cincinnati. The original article was written by Greg Hand. Note: Materials may be edited for content and length.


Cite This Page:

University of Cincinnati. "Long-lost Lake Agassiz offers clues to climate change." ScienceDaily. ScienceDaily, 11 October 2011. <www.sciencedaily.com/releases/2011/10/111005180513.htm>.
University of Cincinnati. (2011, October 11). Long-lost Lake Agassiz offers clues to climate change. ScienceDaily. Retrieved January 28, 2015 from www.sciencedaily.com/releases/2011/10/111005180513.htm
University of Cincinnati. "Long-lost Lake Agassiz offers clues to climate change." ScienceDaily. www.sciencedaily.com/releases/2011/10/111005180513.htm (accessed January 28, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Wednesday, January 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Aquaponics Turn Suburban Industrial Park Into Farmland: Hume

Aquaponics Turn Suburban Industrial Park Into Farmland: Hume

The Toronto Star (Jan. 27, 2015) — Ancient techniques of growing greens with fish and water are well ahead of Toronto bylaws. Video provided by The Toronto Star
Powered by NewsLook.com
Madagascar Locust Plague Could Mean Famine For Millions

Madagascar Locust Plague Could Mean Famine For Millions

Newsy (Jan. 27, 2015) — The Food and Agriculture Organization says millions could face famine in Madagascar without more funding to finish locust eradication efforts. Video provided by Newsy
Powered by NewsLook.com
Storm Slams New England, Spares Mid-Atlantic

Storm Slams New England, Spares Mid-Atlantic

AP (Jan. 27, 2015) — A howling blizzard with wind gusts over 70 mph heaped snow on Boston along with other stretches of lower New England and Long Island on Tuesday, but failed to live up to the hype in Philadelphia and New York City. (Jan. 27) Video provided by AP
Powered by NewsLook.com
Mexico's Volcano of Fire Erupts Again

Mexico's Volcano of Fire Erupts Again

Reuters - News Video Online (Jan. 26, 2015) — A huge plume of smoke shoots into the air as activity in Mexico&apos;s Volcano of Fire picks up again. Rough Cut (no reporter narration). Video provided by Reuters
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