Good news (?) – coal reserves may be far smaller than thought
December 25th, 2008Dave Rutledge, chair of Caltech’s engineering and applied sciences division, says Earth’s coal reserves are far smaller than we think. He estimates that humans will only pull up a total – including all past mining – of 662 billion tons of coal out of the Earth. That’s a lot less than the conventional wisdom. The World Energy Council, for example, says that the world has almost 850 billion tons of coal still left to be mined.
If Rutledge is right, that’s good news for climate – but maybe not such good news for our grandchildren. We’ll have squandered their energy inheritance in an orgy of self-indulgence.
This graph uses Rutledge’s estimates for coal reserves, along with oil and natural gas assessments from ASPO.
According to Rutledge, the world could burn all the world’s coal and other fossil fuels and the atmospheric concentration of CO2 would only end up around 460 parts per million, which is predicted to cause a 2-degree-Celsius rise in global temperatures.
That’s far above the 350 ppm Hansen and others warn is the target we need to hit if we are to avoid passing tipping points, sending Earth into a spiral of catastrophic climate change, But it’s far short of devastating scenarios laid out by the Intergovernmental Panel on Climate Change. There is more than enough coal to keep CO2 well above 350 ppm well beyond this century, even if Rutledge is right.
Whether Rutledge is right or not, the imperative to develop non–fossil-fuel energy sources remains.