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Biology articles
The Golden Goose Is Awarded
Salmonella Strain Spreads Alongside HIV
Fair Flu Viruses Closely Matched
Creative Emulsification
Inflammation for Regeneration
Editor's choice in microbiology
Debate Over Stem Cell Effectiveness
Editor's choice in molecular biology
Telomeres Affect Gene Expression
Re-sensitizing Resistant Bacteria
Vitamin C Slays TB Bacteria
Plant scientists, innovators
The First Plant Interactome
Plant RNAs Found in Mammals
Opinion: Beyond the Model
Sweet and Sour Science
Plant RNA Paper Questioned
Flower Barcodes
Microbial Perfume
How Plants Feel
New Databases Harvest a Rich Bounty of Information on Crop Plant Metabolism
Carnegie Institution for Science Receives Grand Challenges Explorations Grant
Genetically engineered trees could help restore devastated American chestnut
Evolution coup: study reveals how plants protect their genes
  Plants Put Limit on Ice Ages
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.”
Plants Put Limit on Ice Ages
Carnegie donates landmark clones to biology
Plants on Steroids: Key Missing Link Discovered
Gene Function Discovery: Guilt by Association
Cracking the Plant-Cell Membrane Code
Private Support Helps Public Plant Research
Scientists Watch Cell-Shape Process for First Time
How plants choose their mates
Mastermind Steroid Found in Plants
Unlocking the secrets of a plant’s light sensitivity
Nailing down a crucial plant signaling system
What makes a plant a plant?
New component of a plant steroid-activated pathway discovered
Big Boost to Plant Research
The Heart of the Plant
New tool offers unprecedented access for root studies
Steroids control gas exchange in plants
Plant toughness: Key to cracking biofuels?
Amoeba may offer key clue to photosynthetic evolution
The future of plant science – a technology perspective
Plant research funding crucial for the future
Wolf B. Frommer Receives Bogorad Award for Excellence in Plant Biology
Lighting up the plant hormone “command system”
Plant organ development breakthrough
Breakthrough: How salt stops plant growth
New Cancer Diagnostic Technique Debuts
Plant Science Could Ease Global Food and Fuel Demands
Have you had your cereal today?
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Researchers close in on engineering recognizable, drug-free Cannabis plant
UC Riverside Researchers Develop Genetic Map for Cowpea
New research shows how mobile DNA survives—and thrives—in plants, animals
Cucumber Genome Published
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