Featured Research

from universities, journals, and other organizations

Ice-free Arctic may be in our future, international researchers say

Date:
May 9, 2013
Source:
University of Massachusetts at Amherst
Summary:
Analyses of the longest continental sediment core ever collected in the Arctic provide "absolutely new knowledge" of Arctic climate from 2.2 to 3.6 million years ago. The research has major implications for understanding how the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today.

Melting icebergs by the coast of Greenland.
Credit: © kavring / Fotolia

Analyses of the longest continental sediment core ever collected in the Arctic, recently completed by an international team led by Julie Brigham-Grette of the University of Massachusetts Amherst, provide "absolutely new knowledge" of Arctic climate from 2.2 to 3.6 million years ago.

Related Articles


"While existing geologic records from the Arctic contain important hints about this time period, what we are presenting is the most continuous archive of information about past climate change from the entire Arctic borderlands. As if reading a detective novel, we can go back in time and reconstruct how the Arctic evolved with only a few pages missing here and there," says Brigham-Grette.

Results of analyses that provide "an exceptional window into environmental dynamics" never before possible were published this week in Science and have "major implications for understanding how the Arctic transitioned from a forested landscape without ice sheets to the ice- and snow-covered land we know today," she adds.

Their data come from analyzing sediment cores collected in the winter of 2009 from ice-covered Lake El'gygytgyn, the oldest deep lake in the northeast Russian Arctic, located 100 km north of the Arctic Circle. "Lake E" was formed 3.6 million years ago when a meteorite, perhaps a kilometer in diameter, hit the Earth and blasted out an 11-mile (18 km) wide crater. It has been collecting sediment layers ever since. Luckily for geoscientists, it lies in one of the few Arctic areas not eroded by continental ice sheets during ice ages, so a thick, continuous sediment record was left remarkably undisturbed. Cores from Lake E reach back in geologic time nearly 25 times farther than Greenland ice cores that span only the past 140,000 years.

"One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene [~ 3.6 to 2.2 million years ago] when others have suggested atmospheric CO2 was not much higher than levels we see today. This could tell us where we are going in the near future. In other words, the Earth system response to small changes in carbon dioxide is bigger than suggested by earlier climate models," the authors state.

Important to the story are the fossil pollen found in the core, including Douglas fir and hemlock. These allow the reconstruction of vegetation around the lake in the past, which in turn paints a picture of past temperatures and precipitation.

Another significant finding is documentation of sustained warmth in the Middle Pliocene, with summer temperatures of about 59 to 61 degrees F [15 to 16 degrees C], about 14.4 degrees F [8 degrees C] warmer than today, and regional precipitation three times higher. "We show that this exceptional warmth well north of the Arctic Circle occurred throughout both warm and cold orbital cycles and coincides with a long interval of 1.2 million years when other researchers have shown the West Antarctic Ice Sheet did not exist," Brigham-Grette notes. Hence both poles share some common history, but the pace of change differed.

Her co-authors, Martin Melles of the University of Cologne and Pavel Minyuk of Russia's Northeast Interdisciplinary Scientific Research Institute, Magadan, led research teams on the project. Robert DeConto, also at UMass Amherst, led climate modeling efforts. These data were compared with ecosystem reconstructions performed by collaborators at universities of Berlin and Cologne.

The Lake E cores provide a terrestrial perspective on the stepped pacing of several portions of the climate system through the transition from a warm, forested Arctic to the first occurrence of land ice, Brigham-Grette says, and the eventual onset of major glacial/interglacial cycles. "It is very impressive that summer temperatures during warm intervals even as late as 2.2 million years ago were always warmer than in our pre-Industrial reconstructions."

Minyuk notes that they also observed a major drop in Arctic precipitation at around the same time large Northern Hemispheric ice sheets first expanded and ocean conditions changed in the North Pacific. This has major implications for understanding both what drove the onset of the ice ages

The sediment core also reveals that even during the first major "cold snap" to show up in the record 3.3 Million years ago, temperatures in the western Arctic were similar to recent averages of the past 12,000 years. "Most importantly, conditions were not 'glacial,' raising new questions as to the timing of the first appearance of ice sheets in the Northern Hemisphere," the authors add.

This week's paper is the second article published in Science by these authors using data from the Lake E project. Their first, in July 2012, covered the period from the present to 2.8 million years ago, while the current work addresses the record from 2.2 to 3.6 million years ago. Melles says, "This latest paper completes our goal of providing an overview of new knowledge of the evolution of Arctic change across the western borderlands back to 3.6 million years and places this record into a global context with comparisons to records in the Pacific, the Atlantic and Antarctica."

The new Lake E paleoclimate reconstructions and climate modeling are consistent with estimates made by other research groups that support the idea that Earth's climate sensitivity to CO2 may well be higher than suggested by the 2007 report of the Intergovernmental Panel on Climate Change.


Story Source:

The above story is based on materials provided by University of Massachusetts at Amherst. Note: Materials may be edited for content and length.


Journal Reference:

  1. Julie Brigham-Grette, Martin Melles, Pavel Minyuk, Andrei Andreev, Pavel Tarasov, Robert DeConto, Sebastian Koenig, Norbert Nowaczyk, Volker Wennrich, Peter Rosιn, Eeva Haltia, Tim Cook, Catalina Gebhardt, Carsten Meyer-Jacob, Jeff Snyder, and Ulrike Herzschuh. Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia. Science, 9 May 2013 DOI: 10.1126/science.1233137

Cite This Page:

University of Massachusetts at Amherst. "Ice-free Arctic may be in our future, international researchers say." ScienceDaily. ScienceDaily, 9 May 2013. <www.sciencedaily.com/releases/2013/05/130509142048.htm>.
University of Massachusetts at Amherst. (2013, May 9). Ice-free Arctic may be in our future, international researchers say. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2013/05/130509142048.htm
University of Massachusetts at Amherst. "Ice-free Arctic may be in our future, international researchers say." ScienceDaily. www.sciencedaily.com/releases/2013/05/130509142048.htm (accessed October 25, 2014).

Share This



More Earth & Climate News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) — EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) — A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) — Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. 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:

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