The end result of the 21st century will be that we will use every single gram of fossil fuel of every type (petroleum, natural gas, coal) that can be dug up for less cost than wind/solar. The more reserves we find, the more carbon winds up in the atmosphere. Environmental handwringing will be about as effective as standing in front of an oncoming train and whispering "stop, please". At best, the environmentalists will succeed in slowing fossil fuel consumption down by a decade or two before we hit the inevitable wall of it no longer being economically viable.

Meanwhile, we'll slam into Hubbert's Peak at the global level some years before the dinosaur farts run out, resulting in a steep drop in energy availability and a steep increase in cost. This will send shockwaves through the global economy, and set off resource wars the likes of which we've never seen.

If we're very, very smart, and very, very lucky, we won't see half the population of the Earth wiped out in resource wars and famine during this century. :(