Greenhouse-Icehouse Key? Episodic Purging of 'Carbonate Capacitor' Drives Long-Term Climate Cycle

Humans are causing a large increase in carbon dioxide ant other greenhouse gases by burning fossil fuels that are normally buried. As to be expected, it is having the same effect as the release of CO2 by natural means: warming our planet.

I suspect asteroid strikes could be another trigger of large-scale volcanic eruptions.

http://www.sciencedaily.com/releases/2013/02/130207115014.htm

Feb. 6, 2013 — A new Rice University-led study finds the real estate mantra "location, location, location" may also explain one of Earth's enduring climate mysteries. The study suggests that Earth's repeated flip-flopping between greenhouse and icehouse states over the past 500 million years may have been driven by the episodic flare-up of volcanoes at key locations where enormous amounts of carbon dioxide are poised for release into the atmosphere.

"We found that Earth's continents serve as enormous 'carbonate capacitors,'" said Rice's Cin-Ty Lee, the lead author of the study in this month's GeoSphere. "Continents store massive amounts of carbon dioxide in sedimentary carbonates like limestone and marble, and it appears that these reservoirs are tapped from time to time by volcanoes, which release large amounts of carbon dioxide into the atmosphere."

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Lee and colleagues found that the planet's greenhouse-icehouse oscillations are a natural consequence of plate tectonics. The research showed that tectonic activity drives an episodic flare-up of volcanoes along continental arcs, particularly during periods when oceans are forming and continents are breaking apart. The continental arc volcanoes that arise during these periods are located on the edges of continents, and the magma that rises through the volcanoes releases enormous quantities of carbon dioxide as it passes through layers of carbonates in the continental crust.

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