[anon7725]

> By my back of the envelope calculations, we produce something like 300kg of CO2 annually simply by breathing. I would prefer to continue to live, however.

The CO2 that you exhale came from elements that were fairly recently part of an animal or vegetable - ie part of an active and ongoing carbon cycle, rather than deposited into the ground 100M years ago and pulled out to be inserted into the system.

Carbon cycles aren't bad - they're fundamental to life on Earth, obviously. It's making the system unstable by continuous addition that causes the problem.