Read the whole of Bill McKibben's excellent post at MoJo but this really jumped out at me.

If we spew 565 gigatons more carbon into the atmosphere, we'll quite possibly go right past that reddest of red lines. But the oil companies, private and state-owned, have current reserves on the books equivalent to 2,795 gigatons—five times more than we can ever safely burn. It has to stay in the ground.

Put another way, in ecological terms it would be extremely prudent to write off $20 trillion worth of those reserves. In economic terms, of course, it would be a disaster, first and foremost for shareholders and executives of companies like ExxonMobil (and people in places like Venezuela).

If you run an oil company, this sort of write-off is the disastrous future staring you in the face as soon as climate change is taken as seriously as it should be, and that's far scarier than drought and flood. It's why you'll do anything—including fund an endless campaigns of lies—to avoid coming to terms with its reality.

Thus the carbon bubble: "the business models at the center of our economy are in the deepest possible conflict with physics and chemistry".