Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

CO2 higher today than last 2.1 million years

22.06.2009
Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the earth's cycles of cooling and warming.

The study, in the June 19 issue of the journal Science, is the latest to rule out a drop in CO2 as the cause for earth's ice ages growing longer and more intense some 850,000 years ago. But it also confirms many researchers' suspicion that higher carbon dioxide levels coincided with warmer intervals during the study period.

The authors show that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change.

In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years.

The planet has undergone cyclic ice ages for millions of years, but about 850,000 years ago, the cycles of ice grew longer and more intense—a shift that some scientists have attributed to falling CO2 levels. But the study found that CO2 was flat during this transition and unlikely to have triggered the change.

"Previous studies indicated that CO2 did not change much over the past 20 million years, but the resolution wasn't high enough to be definitive," said Hönisch. "This study tells us that CO2 was not the main trigger, though our data continues to suggest that greenhouse gases and global climate are intimately linked."

The timing of the ice ages is believed to be controlled mainly by the earth's orbit and tilt, which determines how much sunlight falls on each hemisphere. Two million years ago, the earth underwent an ice age every 41,000 years. But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million years—a change too great to be explained by orbital variation alone.

A global drawdown in CO2 is just one theory proposed for the transition. A second theory suggests that advancing glaciers in North America stripped away soil in Canada, causing thicker, longer lasting ice to build up on the remaining bedrock. A third theory challenges how the cycles are counted, and questions whether a transition happened at all.

The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research.

"We know from looking at much older climate records that large and rapid increase in C02 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic," he said. "We're heading in that direction now."

The idea to approximate past carbon dioxide levels using boron, an element released by erupting volcanoes and used in household soap, was pioneered over the last decade by the paper's coauthor Gary Hemming, a researcher at Lamont-Doherty and Queens College. The study's other authors are Jerry McManus, also at Lamont; David Archer at the University of Chicago; and Mark Siddall, at the University of Bristol, UK.

Funding for the study was provided by the National Science Foundation.

Copies of the paper, "Atmospheric Carbon Dioxide Concentrations Across the Mid-Pleistocene Transition" are available from the authors or from Science at 202-326-6440 or scipak@aaas.org.

Scientists contacts:

Bärbel Hönisch, hoenisch@ldeo.columbia.edu
Gary Hemming, hemming@ldeo.columbia.edu Cell: 646-701-2974
Jerry McManus, jmcmanus@ldeo.columbia.edu Ph: 845-365-8722

Kim Martineau | EurekAlert!
Further information:
http://www.ei.columbia.edu

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>