The Pace of Progress

Will Rosenfelds Law be enough to save us?
Given we have (max) a century to figure this shit out before we completely cook ourselves, my guess is a cautious maybe...
Why a century, you ask? Physics, I answer:

For every 4Gt Co2 we emit, the atmospheric concentration goes up by about 1ppm. The global economy emits roughly 8Gt/yr. Between 400-550ppm, temperature increases correspond to roughly to 1degree increase/50ppm increase. But above 550ppm, increases can jump to around 1-2degrees/50ppm...so by 650ppm we are committed to over 5degrees average surface temperature increase, at which point Denver will be tropics. (or more probably a desert...)
Most scientists agree that 350ppm is the concentration we need stabilize at in order to preserve the world climate as it is today. But this implies almost zero emissions in the next fifty years...likely? Hmm. No. So lets give it some wiggle room- say 550ppm. (This still commits us to between 2.3-4degrees increase in average temperature- a potentially catastrophic gamble, but one we are well on the path to making) Since C02 hangs around for centuries, to stabalize at 550ppm we can emit no more than 720Gt Co2 EVER. Thats total, for everything society does over the next several thousand years. Given our current and ever-increasing rate of 8Gt/yr, that gives us just 90 short years to stop emitting completely before we cross the 550ppm threshhold, and, well...