The recent volcanic eruptions in Iceland have pointed up just how critical getting a handle on greenhouse emissions is. Typically volcanos inject large amounts of CO2 and other gasses into the atmosphere during eruptions, sometimes dwarfing the rather puny efforts made thus far to reduce the man-made contribution. The really scary part is the large positve feedback potential from methane released from thawing permfrost and decomposing methane hydrates in the ocean bottoms as the climate continues to warm.
