We've taken a great big schloop of carbon out of the ground and squirted it up into the air as CO2 and methane. Pre-industrial CO2 was 280 parts per million; now it's 380 and rising at 2ppm/year (2005: 2.2ppm/year and rising ...). And the rate at which it's rising is rapidly accelerating because traditional sinks of carbon - ie. the Amazon - are getting heated up to the point that they're rotting as methane (28 times more powerful greenhouse gas than CO2 anyway) and actually becoming carbon sources.

You're probably aware of nasty things happening because of this right now. But I don't think you're aware of how bad it is. http://www.guardian.co.uk/uk_news/story/0,3604,1580627,00.html says that ocean acidity is increasing so fast that by 2050 krill and similar critters won't be able to form shells - which will so disrupt all ocean ecosystems that a massive global aquatic dieback will flood the atmosphere with methane ... and KillAllHumans. 

Unless we figure out how to PutTheCarbonBack.

PleaseMoveThisToTheAdjunct