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Plants might have saved Earth from runaway freezing

Date: 07-Jul-09
Author: Carnegie Institution of Washington

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 2 July 2009 Nature report on the missing piece of the puzzle – plants.

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.

Plants on land might have saved the Earth from a deep frozen fate. Courtesy: Andrew Yee.

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.

Full story: Plants Put Limit on Ice Ages

Related link:

• Yale University news release