. 24/7 Space News .
ICE WORLD
How meltwater from the ice sheets disturbed the climate 10,000 years ago
by Staff Writers
Bochum, Germany (SPX) Jul 22, 2016


illustration only

Today, a negative correlation is observed in the amount of rainfall in north-western Africa and north-western Europe. If a humid winter climate prevails in north-western Europe, the climate in north-western Africa is dry. Due to melting ice sheets, this correlation was reversed in the early Holocene period; this resulted in both regions being humid respectively dry at the same time. Radical climate change occurred. The researchers have published their report in the current edition of Nature Geoscience.

Winter climate in north-western Europe and in the Mediterranean region is controlled by the North Atlantic Oscillation (NAO), i.e. the variation in the difference of atmospheric pressure between the Azores high in the south and the Icelandic low in the north. The researchers aimed to find out how the NAO will respond to melting ice sheets and glaciers around the North Atlantic as they are doing now due to climate change.

Climate journal from the cave
To this end, they used speleothems as climate archives: they were able to demonstrate that the ratio of the oxygen isotopes 18O and 16O contained therein is affected by, among other factors, the amount of rainfall. With the aid of speleothems in north-western Morocco and western Germany, they were able to draw conclusions regarding the climate in those regions for the early to late Holocene period from 11,700 to 2,500 years ago.

The researchers show that on multi-decadal to multi-centennial timescales a negative correlation existed between the amount of rainfall in both regions druing during the mid-Holocene from 8,000 to 5,900 years ago and the late Holocene from 4,700 to 2,500 years ago. That means that one region experienced less rainfall when the other experienced a lot, just like today. In the early Holocene, however, a positive correlation existed between both regions. During the transition from the mid to the late Holocene, the correlation reversed.

Climate simulations illustrate how climate reacts to the melting of ice
In order to identify the reasons for this behaviour, the team carried out climate simulations using a coupled atmosphere and ocean model.

"A possible explanation for the negative correlation is the melting of the North American ice sheet in the early Holocene period," explains Jasper Wassenburg, who conducted the analyses in collaboration with Prof Dr Adrian Immenhauser at the Department of Sediment and Isotope Geology at the Ruhr-Universitat Bochum and is now at the Institute of Geosciences at Johannes Gutenberg University Mainz. During the most recent ice age, this ice sheet covered large areas of Canada. Huge volumes of meltwater flowed into the North Atlantic and changed its circulation pattern.

"Using the simulations of our climate model, we demonstrated that the positive correlation of rainfall in Morocco and Germany is caused by a combination of effects: namely the impact of the North American ice shield on the atmospheric circulation and the impact of its meltwater on the oceanic circulation," explains Dr Stephan Dietrich, who evaluated the simulations at the Alfred-Wegener-Institut, Helmholtz-Zentrum fur Polar- und Meeresforschung and is now at the Bundesanstalt fur Gewasserkunde in Koblenz.

Ice sheet had a strong cooling effect
Atmospheric circulation patterns such as the NAO are determined by atmospheric pressure patterns that occur as a result of heating and cooling of air. Oceanic currents play an important role, because they affect the distribution of heat and, thus, atmospheric circulation. The North American ice sheet has a strong cooling effect: snow and ice reflect most of the solar radiation; researchers refer to this as the albedo-effect. This was the reason why a stable high-pressure field developed above the ice sheet.

Moreover, the meltwater affected the strength of ocean currents, especially the North Atlantic Current. "Even though the precise mechanisms have not yet been fully understood, it is very likely that these effects were essential factors that caused the positive correlation of rainfall in Morocco and Germany to reverse into a negative one, due to the melting of the North American ice sheet," explains Jasper Wassenburg.

Similar scenario is conceivable
If the ice in Greenland melts and the meltwater flows into the North Atlantic, a scenario similar to the one that caused the change of the NAO in the early Holocene period might occur, according the researchers. "However, the climate conditions in the early and late Holocene differed considerably. This is why it is difficult to predict if and how NAO will be affected," conclude the researchers.

"We suggest that it all depends on the speed at which the ice in Greenland will melt and on the volume of meltwater." Detailed reconstructions of the climate and precise measurements of the changes in Greenland ice are necessary in order to understand the mechanisms that contribute to the changes in correlation patterns.

The study was conducted by researchers from Ruhr-Universitat Bochum, Johannes Gutenberg University Mainz, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research -, Bundesanstalt fur Gewasserkunde, Helmholtz Centre for Ocean Research Kiel (GEOMAR), Ruprecht Karls University Heidelberg, Innsbruck University, Faculty of Sciences Dhar Mahraz Fes, and Max Planck Institute for Chemistry in Mainz.

Jasper A. Wassenburg, Stephan Dietrich, Jan Fietzke, Jens Fohlmeister, Klaus Peter Jochum, Denis Scholz, Detlev K. Richter, Abdellah Sabaoui, Christoph Spotl, Gerrit Lohmann, Meinrat O. Andreae and Adrian Immenhauser. Reorganization of the North Atlantic Oscillation during early Holocene deglaciation, in: Nature Geoscience, 2016, DOI: 10.1038/ngeo2767


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Ruhr-University Bochum
Beyond the Ice Age






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
ICE WORLD
Super-slow circulation allowed world's oceans to store huge amounts of carbon during last ice age
Cambridge UK (SPX) Jun 30, 2016
The way the ocean transported heat, nutrients and carbon dioxide at the peak of the last ice age, about 20,000 years ago, is significantly different than what has previously been suggested, according to two new studies. The findings suggest that the colder ocean circulated at a very slow rate, which enabled it to store much more carbon for much longer than the modern ocean. Using the infor ... read more


ICE WORLD
Taiwan to make lunar lander for NASA moon-mining mission

NASA camera catches moon 'photobombing' Earth

Russia to spend $60M in 2016-2018 to fund space voyages to Moon, Mars

Russian Moon Base to Hold Up to 12 People

ICE WORLD
NASA Selects Five Mars Orbiter Concept Studies

Next Mars Rover Progresses Toward 2020 Launch

Mars Canyons Study Adds Clues about Possible Water

Curiosity Mars Rover Enters Precautionary Safe Mode

ICE WORLD
Disney theme park in Shanghai nears a million visitors

Sensor Technology Could Revolutionize What You Sleep On

Return to light for underground astronauts

Mathematical framework prioritizes key patterns to accelerate scientific discovery

ICE WORLD
Dutch Radio Antenna to Depart for Moon on Chinese Mission

Chinese Space Garbageman is not a Weapon

China to launch its largest carrier rocket later this year

China committed to peaceful use of outer space

ICE WORLD
Russia launches ISS-bound cargo ship

New Crew Members, Including NASA Biologist, Launch to Space Station

Russian New Soyuz-MS Spacecraft Docks With ISS for First Time

NASA Highlights Space Station Research Benefits, Opportunities at San Diego Conference

ICE WORLD
SpaceX propels cargo to space station, lands rocket

SpaceX to launch key 'parking spot' to space station

Russia to Continue Rocket Engine Supplies to US Under Existing Contracts

India launches 20 satellites in single mission

ICE WORLD
Surface Composition Determines Planet's Temperature and Habitability

Warm Jupiters Not as Lonely as Expected

NASA's Kepler discovers more than 104 new exoplanets

Behind the scenes of protostellar disk formation

ICE WORLD
Rice's 'antenna-reactor' catalysts offer best of both worlds

'Green' electronic materials produced with synthetic biology

'Jumping film' harnesses the power of humidity

Chemists create microscopic and malleable building blocks









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.