A recent article by Bill McKibben has three (actually four) incredibly important numbers that we all need to know and use.

Two degrees Celsius is the maximum amount of warming that the planet can stand without fundamental damage to our way of life. Actually many scientists now view that as overly optimistic, given the amount of damage (heat waves, droughts fires and floods) we are seeing with just 0.8 degrees Celsius.

565 Gigatons is the amount of carbon we can put into the atmosphere before hitting that 2 degrees Celsius. Our current rate of addition is about 32 Gigatons per year, and that rate has been edging upward by about 3 % per year, notwithstanding global efforts at renewables, energy conservation, and the Kyoto protocol. The rate of increase has been remarkably stable, regardless of all the scientific data on climate change and the policy changes discussed worldwide.

The current proven reserves of fossil fuels contain 2795 Gigatons of carbon. This is the "proven" reserves, the reserves that fossil fuel companies already know they have on hand, the amount that is reflected in their stock prices, the stuff they bought with every intention of getting it out and burning it, and that their stockholders fully expect them to get out and burn. This does not include any future discoveries or speculative fuels, this is proven reserves that they now own.

If we can not exceed 565 gigatons, and we continue adding 32 gigatons per year, and rising, we will exceed the maximum tolerable dose in 16 years. That means if your kid is in kindergarten today, catastrophic climate change strikes the whole planet before he leaves highschool. Those who think of climate change as some far off event, need to realize that fundamental change must come very soon, or it is "game over".

So this means we must convince the fossil fuel companies to leave 80 % of their proven reserves in the ground, or the planet dies. Anyone who thinks that Exxon or Arch Coal will have spent the kind of money they did to buy these reserves and will just walk away from them in order to save the planet, has not been paying attention. McKibben argues that the environmental movement needs to clearly identify the "enemy", in order to get the attention of the masses, ans these numbers should clearly identify fossil fuel companies as the "enemy" in the minds of most Americans.