Hubbert Hearts Hansen
The Hubbert curve was introduced by, Hubbert, M. King. It predicts that production of any natural resource will follow a bell shaped curve, a reasonable idea. The background is that the yield individual exploitable deposits ranges from a little bit in very rich digs to a lot in poor ones. At first before demand has grown, the rich deposits are mined, as demand grows, the more common medium size lodes are mined, but we get better at it so the net production increases until finally only the really lean stuff is left and production falls as the cost per unit soars. The result is that production as a function of time follows a bell shaped curve. The idea took off when Hubbert predicted the peak production of oil in the US.
Richard Kerr in Science discusses Ol' King Hubbert's coal curve. The general way of estimating coal is to try and gauge the amount from exploration. Lots of holes have been dug and geologists think they have a good idea of what is underneath. If you do this, you get estimates of 100+ years of reserves and a lot of CO2 pumped into the air during combustion. These estimates have been declining sharply in recent years as the rock jocks get serious. David Rutledge has been looking at the estimates for coal reserves and finds them to be systematically overestimated. He quotes Kenneth Deffeyess
When USGS workers tried to estimate resources, they acted, well, like bureaucrats. Whenever a judgment call was made about choosing a statistical method, the USGS almost invariably tended to pick the one that gave the higher estimate.”Rutledge estimates that 90% of coal reserves will be gone by 2070 (he says 2069, but that is engineer speak). Other groups put peak coal at 2020. In any case what is left after 2070 is gonna not be very good. You can, if you try hard enough burn dirt, which is what the Germans do with brown coal.
First the good news, if coal reserves are a factor of four or less than estimated, burning coal will bring us into a dangerous area, 3 C higher temperatures, but not necessarily a disastrous one.
The other news is, as Rutledge says, we have to start shifting energy sources right now in order to deal with the loss of fossil fuel sources as well as climate change
The bad news is tar sands and shale.
Eli is a cheery bunny, but you knew that