If you haven't read Bill McKibben's new piece in Rolling Stone Global Warming's Terrifying New Math, do so. It's well worth it—though in all truth, for the most avid TreeHugger readers, you're probably aware of much of what McKibben presents. But even if you're in that camp I want to present one really serious part of the 'new math' presented.
Consider this: If we're going to keep temperature rise below 2°C (a figure it increasingly appears is still too high to avoid some serious climate impacts, but it is internationally agreed to), then we have about 565 gigatons more CO2 we can send into the atmosphere over the next four decades or so.
Then consider: The amount of carbon contained in the proven coal, oil and gas reserves of national oil companies and private corporations is about five times higher than this, 2795 gigatons.
In other words, we simply cannot allow that fuel to be extracted and used, if we're going to preserve the climate in anything like a state we've grown accustomed over the recorded history of human civilization.
You really should read the whole piece, and to further entice you, consider how Bill describes the gap between these proven reserves and how much more carbon we can emit:
Think of two degrees Celsius as the legal drinking limit – equivalent to the 0.08 blood-alcohol level below which you might get away with driving home. The 565 gigatons is how many drinks you could have and still stay below that limit – the six beers, say, you might consume in an evening. And the 2,795 gigatons? That's the three 12-packs the fossil-fuel industry has on the table, already opened and ready to pour.
If there's one overarching thing these numbers say to me, it's that we cannot leave these decisions, to burn or not burn these fossil fuels, to either the corporations profiting from them (handsomely) and buying our political system, or to market forces.
We have to make the values judgement that we will take no more of this. No new drilling, no new exploration, we're done.