Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants put limit on ice ages

03.07.2009
When glaciers advanced over much of the Earth's surface during the last ice age, what kept the planet from freezing over entirely?

This has been a puzzle to climate scientists because leading models have indicated that over the past 24 million years geological conditions should have caused carbon dioxide levels in the atmosphere to plummet, possibly leading to runaway "icehouse" conditions. Now researchers writing in the July 2, 2009, Nature report on the missing piece of the puzzle – plants.

"Atmospheric CO2 concentrations have been remarkably stable over the last 20 or 25 million years despite other changes in the environment," says co-author Ken Caldeira of the Carnegie Institution's Department of Global Ecology. "We can look to land plants as the primary buffering agent that's held CO2 in such a narrow range during this time."

The research team, led by Mark Pagani of Yale University, found that the critical role of plants in the chemical breakdown and weathering of rocks and soil gave them a strong influence on carbon dioxide levels. It was a link that earlier studies had missed.

Over geologic time, large volumes of carbon dioxide have been released into the atmosphere by volcanoes. This would cause CO2 to build up in the atmosphere were it not for countervailing geologic processes of sedimentation, which bury carbon-containing minerals in the crust, sequestering it from the atmosphere. The overall rate of sedimentation is controlled by the upthrust of mountains and the erosion and chemical breakdown of their rocks. The rise of the Andes, Himalayas, Tibetan Plateau, and mountain ranges in western North America over the past 25 million years would have been expected to have cause faster weathering and erosion, and therefore a faster burial of carbon drawn from the atmosphere. But the stability of carbon dioxide levels indicate that this didn't happen. Why not?

This is where the plants come in. "The rates of weathering reactions are largely controlled by plants. Their roots secrete acids that dissolve minerals, they hold soils, and they increase the amount of carbon dissolved in groundwater," says Caldeira. "But when levels of carbon dioxide get too low, the plants basically suffocate and the weathering slows down. That means less sediment is eroded from the uplands and less carbon can be buried. It's a negative feedback on the system that has kept carbon dioxide levels from dropping too low."

Extremely low carbon dioxide levels would have reduced the atmosphere's ability to retain heat, putting the planet into a deep freeze. "So you could say that by limiting the drawdown of CO2 by chemical weathering and sedimentation, plants saved the planet from freezing over," says Caldeira.

Could plants save us from rising carbon dioxide from human emissions and harmful greenhouse warming? No, says Caldeira. "We are releasing CO2 to the atmosphere about 100 times faster than all the volcanoes in the world put together. While these weathering processes will eventually remove the CO2 we are adding to the atmosphere, they act too slowly to help us avoid dangerous climate change. It will take hundreds of thousands of years for these rock weathering processes to remove our fossil fuel emissions from the atmosphere."

The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science. The Department of Global Ecology, located in Stanford, California, was established in 2002 to help build the scientific foundations for a sustainable future. Its scientists conduct basic research on a wide range of large-scale environmental issues, including climate change, ocean acidification, biological invasions, and changes in biodiversity.

Ken Caldeira | EurekAlert!
Further information:
http://www.ciw.edu

More articles from Earth Sciences:

nachricht Volcanoes and glaciers combine as powerful methane producers
20.11.2018 | Lancaster University

nachricht Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Nonstop Tranport of Cargo in Nanomachines

20.11.2018 | Life Sciences

Researchers find social cultures in chimpanzees

20.11.2018 | Life Sciences

When AI and optoelectronics meet: Researchers take control of light properties

20.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>