Quote from futurecurrents:
More cheery stuff...
We simply can't burn all the fossil fuels. A runaway warming -positive feedback loop - is a frightening scenario. Humanity would probably try large scale geo-engineering to prevent it.
"He also explains that the sharp warming that took place during the PaleoceneâEocene Thermal Maximum (PETM) were not caused by fossil fuels (which remained underground), but rather by the release of methane from permafrost and clathrates. If human emissions warm the planet enough to release that methane again, it could add a PETM-level warming on top of the warming caused by human beings.
Hansenâs conclusions are, frankly, terrifying:
The paleoclimate record does not provide a case with a climate forcing of the magnitude and speed that will occur if fossil fuels are all burned. Models are nowhere near the stage at which they can predict reliably when major ice sheet disintegration will begin. Nor can we say how close we are to methane hydrate instability. But these are questions of when, not if. If we burn all the fossil fuels, the ice sheets almost surely will melt entirely, with the final sea level rise about 75 meters (250 feet), with most of that possibly occurring within a time scale of centuries. Methane hydrates are likely to be more extensive and vulnerable now than they were in the early Cenozoic. It is difficult to imagine how the methane clathrates could survive, once the ocean has had time to warm. In that event a PETM-like warming could be added on top of the fossil fuel warming.
After the ice is gone, would Earth proceed to the Venus syndrome, a runaway greenhouse effect that would destroy all life on the planet, perhaps permanently? While that is difficult to say based on present information, Iâve come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty."