Now that Working Group 3 has put its chapters online, all six thousand pages of the IPCC’s 5th Assessment Report have arrived. Coal is the specter that looms.
In the IPCC’s business-as-usual scenario, Representative Concentration Pathway (RCP) 8.5, coal accounts for half of future carbon-dioxide emissions through 2100, and two-thirds of the emissions through 2500. The IPCC’s coal burn is enormous, twice the world reserves by 2100, and seven times reserves by 2500. Coal so dominates that it is not an exaggeration to say that the IPCC and climate-change research programs depend on this massive coal burn for their existence. Without the threat of coal, the IPCC could close up shop and the research program funding would drop to a small fraction of what is spent on research in weather forecasting.
Coal is the oldest of our fossil fuels, and we know a lot about how coal mining grows and how it dies. We also know a lot about coal reserves. The UK produced the first detailed reserves study in a Royal Commission on Coal Supplies in 1871. Dever Ashmead of the US Bureau of Mines compiled a thorough reserves analysis of the Pennsylvania anthracite fields in 1926. The first comprehensive survey at the world level was The Coal Resources of the World, produced in 1913 for the 12th World Geological Congress. After the First World War, the surveys were continued by the World Power Conference. This group, now called the World Energy Council, published its latest survey, the 23rd, in 2013. The Council’s surveys are the primary source for coal reserves.
One thing that distinguishes coal reserves from oil and gas reserves is that historically they have had the goal of serving as an estimate of total national future production. This is explicit in the 1871 Royal Commission charter, and the Commission’s reserves criteria were adopted in the later World Power Council surveys. This is reasonable because coal fields are relatively easy to find and map. This is in contrast to oil and gas, where discovery has been difficult. This can make oil and gas reserves behave like warehouse inventories that are an index of the time that it takes to develop new fields rather than total future production. US oil reserves have been typically been close to the production in the following ten years.
On the other hand, for coal the pattern has been that countries produce only a small fraction of their early reserves, and then late in the production cycle the reserves drop to match the coal at the last working mines. This pattern is seen in the UK (cumulative production of 19% of early reserves), Pennsylvania anthracite (42%), the Ruhr Valley (14%), France and Belgium (23%), and Japan and South Korea (21%). This means that the reserves criteria have been too optimistic, but it also means that world coal reserves are a good upper bound on future production. An IPCC scenario that burns two times or seven times the reserves is utterly at odds with the historical experience.