Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Charcoal Evidence Tracks Climate Changes in Younger Dryas

30.01.2009
A new study reports that charcoal particles left by wildfires in sediments of 35 North American lake beds don't readily support the theory that comets exploding over the continent 12,900 years ago sparked a cooling period known as the Younger Dryas.

The study -- appearing online this week (Jan. 26-31) ahead of regular publication in the Proceedings of the National Academy of Sciences -- however, did find clear links between abrupt climate changes and fire activity during the transition between the last Ice Age and the warm interglacial period that began 11,700 years ago.

These links are also consistent with the impacts of climate-change conditions on wildfires during recent decades in North America, the researchers noted.

Charcoal particles, along with tree pollen, provide snapshots of types of vegetation and frequencies of wildfire activity in a given area, said study co-author Patrick J. Bartlein, a professor of geography at the University of Oregon. His doctoral student Jennifer R. Marlon led the collaborative study of 23 co-authors (including seven current or former UO students) at institutions in the U.S., Canada and Europe.

"The charcoal data don't support the idea of widespread fires at the beginning of the Younger Dryas interval," Bartlein said. "The results don't reject the comet hypothesis, but do suggest that one element of it -- widespread fires -- didn't occur. Instead, the data show that biomass burning tracked general climate changes closely. Biomass burning increased as conditions warmed during deglaciation until the beginning of the Younger Dryas cold interval at 12,900 years ago, leveled off during the cool interval, and then increased again as warming resumed after the end of the cold interval, about 11,700 years ago."

The fires that left the charcoal records reflect the impact of climate changes independent of potential contributions of early Paleoindians who may have been living on the continent. Proponents of the comet theory suggest Clovis culture may have been dramatically disrupted across the continent.

Marlon began the National Science Foundation-sponsored study of charcoal-pollen records soon after the comet theory was proposed in PNAS by an international team of 26 researchers led by Richard B. Firestone. A co-author of that study, UO archaeologist Douglas Kennett, in the Jan. 2 issue of Science, documented the existence of possible comet-triggered nanodiamond-rich soil at six North American sites dating to 12,900 years ago in apparent support of the hypothesis. The formation of nanodiamonds requires intense pressure and heat, much higher than those of biomass wildfires but possible in comet explosions.

"We had the data to look for widespread fires if they had occurred," Marlon said, "but what we saw instead was a general increase in biomass burning whenever the climate warmed."

The lakes containing the charcoal are in Alaska (3 sites), British Columbia (7), U.S. Pacific Northwest (6), the Sierra Nevada (3), northern U.S. Rocky Mountains (6), Southwest (4), Midwest (2), Northeast (3 sites in Quebec), and Southeast (1). Thirty of the samples came from the Global Charcoal Database; another five were drawn from more recent research by co-authors currently studying sediments from the Younger Dryas.

The new study's conclusion that climate is a major control of wildfires matched that of a study published last year in Nature Geosciences by the same researchers on global biomass burning over the last 2,000 years.

"Together," Bartlein said, "these studies suggest that episodes of global warming are accompanied by increases in wildfires."

Co-authors of the study were Marlon, Bartlein and Megan K. Walsh, all currently of the UO; Walsh is a postdoctoral researcher in Kennett's lab. Others were S.P. Harrison of the University of Bristol (UK); K.J. Brown of the Geological Survey of Denmark and Greenland and of the Royal British Columbia Museum in Victoria, B.C.; M.E. Edwards of the University of Southampton (UK) and University of Alaska; P.E. Higuera, C. Briles and C. Whitlock of Montana State University; M.J. Power and A. Brunelle of the University of Utah; R.S. Anderson and M. Daniels of Northern Arizona University; C. Carcaillet of the French National Centre for Scientific Research and University of Montpellier (France); Feng-Sheng Hu of the University of Illinois at Urbana-Champaign; M. Lavoie of Laval University in Quebec City; C. Long of the University of Wisconsin at Oshkosh; T. Minckley of the University of Wyoming; P.J.H. Richard of the University of Montreal; A.C. Scott of the University of London; D.S. Shafer of the Nevada System of Higher Education's Desert Research Institute; W. Tinner of the University of Bern, Switzerland; and C.E. Umbanhowar Jr. of St. Olaf College in Minnesota.

About the University of Oregon
The University of Oregon is a world-class teaching and research institution and Oregon's flagship public university. The UO is a member of the Association of American Universities (AAU), an organization made up of the 62 leading public and private research institutions in the United States and Canada. The University of Oregon is one of only two AAU members in the Pacific Northwest.

Sources: Jennifer Marlon, doctoral student, geography, 203-507-2462 (currently in New Haven, Conn.), jmarlon@uoregon.edu; Patrick Bartlein, professor of geography, 541-346-4967, bartlein@uoregon.edu

Links: Bartlein faculty page: http://geography.uoregon.edu/bartlein/; UO geography department: http://geography.uoregon.edu/

Jim Barlow | Newswise Science News
Further information:
http://www.uoregon.edu

More articles from Earth Sciences:

nachricht AWI researchers measure a record concentration of microplastic in arctic sea ice
24.04.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Climate change in a warmer-than-modern world: New findings of Kiel Researchers
24.04.2018 | Christian-Albrechts-Universität zu Kiel

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Why we need erasable MRI scans

26.04.2018 | Medical Engineering

Balancing nuclear and renewable energy

26.04.2018 | Power and Electrical Engineering

Researchers 3-D print electronics and cells directly on skin

26.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>