[Ecky]

Food for thought:

Anoxic event - Wikipedia, the free encyclopedia

At even a few degrees warmer, rain forests are extremely vulnerable to fire hazards. These forests have little natural resistance to fires,[6] and some conjecture a critical tipping point. Practically overnight the increase of temperature might have been reached and triggered a huge burn-off[6] of planetary forests. This would have released unprecedented amounts of carbon dioxide into the atmosphere. With a change of mean temperatures of three degrees Celsius, the ice caps melted. This triggered a runaway effect. In the super-greenhouse ecologies—the term meaning average temperature rose to or beyond six degrees above today—the seas were so warm, it is believed the water temperatures at the two poles[7] were in the lower 80s°F (i.e. above 27 °C).[3] The Cretaceous and Jurassic periods' world ecologies were essentially ice free,[3] had massive storms driven by warm oceans, and were dying from the double hit[3] of lack of oxygen and toxic hydrogen sulfide accumulations at lower layers because of a shut down in the ocean conveyor belts.[3] In this time, most of the world would experience the highly noxious scent of rotten eggs and the seas would have slowly acquired a deep green hue from the high amounts of algae.

And: http://www.msnbc.msn.com/id/40316649.../#.Tx3Cu28S29U

Gas locked inside Siberia's frozen soil and under its lakes has been seeping out since the end of the last ice age 10,000 years ago. But in the past few decades, as the Earth has warmed, the icy ground has begun thawing more rapidly, accelerating at a perilous rate the release of methane, a greenhouse gas 23 times more powerful than carbon dioxide.

Based on my reading, I don't think we're very near a catastrophic event, but again, food for thought.