Featured Research

from universities, journals, and other organizations

Recent Abrupt Cold Event Could Shed Light On Future

Date:
December 11, 1997
Source:
Penn State
Summary:
About 8,200 years ago, the world climate suddenly got colder and stayed that way for a few hundred years before temperatures returned to normal, according to a team of paleoclimatologists.

San Francisco, Calif. -- About 8,200 years ago, the world climate suddenly got colder and stayed that way for a few hundred years before temperatures returned to normal, according to a team of paleoclimatologists.

"This event, which we are calling the 8k event, was short compared to other, more distant events, lasting only about 200 years" says Anna Maria Agustsdottir, graduate student in geosciences, Penn State. "We see it in the Greenland ice cores as one of the biggest dips during the Holocene."

The Holocene is the geologic period beginning about 10,000 years ago at the end of the last glaciation and continuing up to today. Unlike other events, the 8K takes place in what for geologists is the very recent past.

"Temperatures abruptly decreased about 11 degrees Fahrenheit during the 8K event," Agustsdottir said today (Dec. 10) at the fall meeting of the American Geophysical Union in San Francisco.

The change in climate during this period can be seen not only in the temperature record from the Greenland ice cores, but also in ice accumulation, in the indicators of forest fires and in the amounts of methane found in the atmosphere.

"Methane is not just an indicator of local climate change," says Agustsdottir, "But it indicates a global change in climate."

The researchers, who include Agustsdottir; Richard Alley, professor of geosciences, Penn State; and Peter J. Fawcett of the University of New Mexico, note that during the 8K, Greenland became cold, dry and windy, Canada became cold and the North Atlantic Basin cold and fresh. Asia and Africa also showed colder, dryer climate while South America and North America were wetter.

"This event appears to be very similar to, if some what shorter than, the Younger Dryas event that occurred about 12,000 years ago," says Agustsdottir. "We are trying to find the underlying cause for these sudden temperature drops."

The researchers believe that these events occur when the ocean conveyor system shuts down. This system is a series of currents that normally move warm water from the equatorial zone to the north. This water cools as it moves northward and the colder, saltier water sinks and flows back toward the equator to replace water moving north. Temperature, water density and salinity control ocean currents. When the ocean conveyor shuts down, deep, cold water formation stops in the north and the cyclical flow of water halts, cooling Europe and its surroundings.

"We do not know what shuts down the conveyor, but one possibility is an increase in fresh water in the North Atlantic that would decrease salinity and prevent the water from sinking," says Agustsdottir.

Using a climate simulation model called GENESIS, the researchers are trying to model events leading up to the 8K event to simulate an ocean conveyor shut down and temperature decline. The Penn State researchers have used this method on the Younger Dryas event with some success.

"Using conditions similar to today's oceans, the model response to a conveyor shutdown does not match data from the 8K event," says Agustsdottir. "However, shutdown from an ocean with a more vigorous conveyor does match observations. This indicates that things were different in the early Holocene."

She considers the mechanism behind these sudden cold spells important because the climate changes are so rapid. While we cannot predict the future, we can learn from events in the past and see how they occurred.

"If change is gradual, animals, plants and humans can adapt to the new environment," Agustsdottir says. "If change is abrupt, crops fail, rains do not come or come too frequently and people do not have time to adjust."


Story Source:

The above story is based on materials provided by Penn State. Note: Materials may be edited for content and length.


Cite This Page:

Penn State. "Recent Abrupt Cold Event Could Shed Light On Future." ScienceDaily. ScienceDaily, 11 December 1997. <www.sciencedaily.com/releases/1997/12/971211073756.htm>.
Penn State. (1997, December 11). Recent Abrupt Cold Event Could Shed Light On Future. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/1997/12/971211073756.htm
Penn State. "Recent Abrupt Cold Event Could Shed Light On Future." ScienceDaily. www.sciencedaily.com/releases/1997/12/971211073756.htm (accessed September 17, 2014).

Share This



More Earth & Climate News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Isolated N. Korea Asks For International Help With Volcano

Isolated N. Korea Asks For International Help With Volcano

Newsy (Sep. 16, 2014) Mount Paektu volcano in North Korea is showing signs of life and there's not much known about it. Video provided by Newsy
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:
from the past week

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