Long time management of fossil fuel resources to limit global warming and avoid ice age onsets

There are about 5000 billion tons of fossil fuel carbon in accessible reserves. Combustion of all this carbon within the next few centuries would force high atmospheric CO2 content and extreme global warming. On the other hand, low atmospheric CO2 content favors the onset of an ice age when changes in the Earth's orbit lead to low summer insolation at high northern latitudes. Here I present Earth System Model projections showing that typical reduction targets for fossil fuel use in the present century could limit ongoing global warming to less than one degree Celcius above present. Furthermore, the projections show that combustion pulses of remaining fossil fuel reserves could then be tailored to raise atmospheric CO2 content high and long enough to parry forcing of ice age onsets by summer insolation minima far into the future. Our present interglacial period could be extended by about 500,000 years in this way. Citation: Shaffer, G. (2009), Long time management of fossil fuel resources to limit global warming and avoid ice age onsets, Geophys. Res. Lett., 36, L03704, doi: 10.1029/2008GL036294.