Featured Research

from universities, journals, and other organizations

Plants Save The Earth From An Icy Doom

Date:
July 2, 2009
Source:
Carnegie Institution
Summary:
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 report on the missing piece of the puzzle -- plants.

Researchers 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.
Credit: iStockphoto/Matthias Straka

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."


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Cite This Page:

Carnegie Institution. "Plants Save The Earth From An Icy Doom." ScienceDaily. ScienceDaily, 2 July 2009. <www.sciencedaily.com/releases/2009/07/090701131307.htm>.
Carnegie Institution. (2009, July 2). Plants Save The Earth From An Icy Doom. ScienceDaily. Retrieved April 25, 2014 from www.sciencedaily.com/releases/2009/07/090701131307.htm
Carnegie Institution. "Plants Save The Earth From An Icy Doom." ScienceDaily. www.sciencedaily.com/releases/2009/07/090701131307.htm (accessed April 25, 2014).

Share This



More Earth & Climate News

Friday, April 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Fungus Killing Bats, Spreading in US

Deadly Fungus Killing Bats, Spreading in US

AP (Apr. 24, 2014) A disease that has killed more than six million cave-dwelling bats in the United States is on the move and wildlife biologists are worried. White Nose Syndrome, discovered in New York in 2006, has now spread to 25 states. (April 24) Video provided by AP
Powered by NewsLook.com
New Pictures of Ship That Sank in 1888

New Pictures of Ship That Sank in 1888

AP (Apr. 24, 2014) Federal researchers have released new images of the City of Chester, a steamship that sank in San Francisco Bay in 1888. Researchers recently found the shipwreck while mapping shipping routes. (April 24) Video provided by AP
Powered by NewsLook.com
Risk of Asteroid Hitting Earth Higher Than Thought, Study Shows

Risk of Asteroid Hitting Earth Higher Than Thought, Study Shows

Reuters - US Online Video (Apr. 23, 2014) A group of space explorers say the chance of a city-obliterating asteroid striking Earth is higher than scientists previously believed. Deborah Gembara reports. Video provided by Reuters
Powered by NewsLook.com
UN Joint Mission Starts Removing Landmines in Cyprus

UN Joint Mission Starts Removing Landmines in Cyprus

AFP (Apr. 23, 2014) The UN mission in Cyprus (UNFICYP) led a mine clearance demonstration on Wednesday in the UN-controlled buffer zone where demining operations are being conducted near the Cypriot village of Mammari. Duration: 01:00 Video provided by AFP
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:
from the past week

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