Coal and the IPCC

This is a guest post by Professor Dave Rutledge. A brief biography is given at the end of the post. Cross posted from Climate Etc.

Now that Working Group 3 has put its chapters on line, 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.

Peer-reviewed estimates of future world coal production have been available. One example is my 2011 paper in the Journal of Coal Geology, “Estimating Long-Term World Coal Production with Logit and Probit Transforms“. This paper includes references to other peer-reviewed studies led by Tad Patzek, Chair of the Petroleum and Geosystems Engineering Department at the University of Texas at Austin, and Steve Mohr, at the Sydney University of Technology. All three papers use production histories to make an independent estimate of future production that is less than reserves, but consistent with the historical experience of mining coal.

I searched the 5th Assessment Report for references to coal reserves and I found one quantitative sentence in Working Group 3, Chapter 7, page 15.
“For both reserves and resources, the quantity of hard (black) coal significantly outnumbers the quantity of lignite (brown coal), and despite resources being far greater than reserves, the possibility for resources to cross over to reserves is expected to be limited since coal reserves are likely to last around 100 years at current rates of production (Rogner et al., 2012).” [The Rogner et al. reference is to a chapter in the book Global Energy Assessment by the think-tank IIASA.]

It is true that the R/P (reserves to production) ratio is 109 years. However, the R/P ratio has been dropping rapidly. Ten years ago it was 204 years. It is also true that conversion of resources to reserves is expected to be limited, but for a different reason. Countries end up producing less than their reserves. Most importantly, the statement does not address the problem, which is the large multiple of the coal reserves that is assumed to be produced in the business-as-usual scenario, RCP8.5. There is no precedent for this, and RCP8.5 should not be used for any purpose whatsoever.

The IPCC is actually rather coy about revealing exactly how much coal is burned in RCP8.5. If one goes to the RCP data base, one can find the emissions in 2500 for the insulation chemical HFC245fa, which has a current production of 500t. However, there is nothing for coal, which has a current production of 8Gt. The 2011 paper in Climatic Change by Keywan Riahi et al. that defines the RCP8.5, “RCP 8.5—A scenario of comparatively high greenhouse gas emissions.”, gives a graph (Figure 5), presumably indicative, that shows coal production increasing to 2100, but with no discussion of the fact that it exceeds reserves. For the numbers given here, I digitized this figure and extended the calculation to 2500.

Some thoughts on more realistic projections for future fossil-fuel production were given in an earlier Climate Etc. post, and in a recent invited talk for the Geological Society of America, “Projections for Ultimate Coal Production from Production Histories Through 2012,” I argue that future fossil-fuel CO2 emissions without any climate policy at all are likely to fall between those of the policy scenarios RCP2.6 and RCP4.5.

Biography for David Rutledge
Professor Rutledge is the Tomiyasu Professor of Engineering at Caltech, and a former Chair of the Division of Engineering and Applied Science there. He is a Fellow of the IEEE and a winner of the Teaching Award of the Associated Students at Caltech. He served as the editor for the Transactions on Microwave Theory and Techniques, and is a founder of the Wavestream Corporation, a manufacturer of high-power millimeter-wave transmitters for satellite uplinks.

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13 Responses to Coal and the IPCC

  1. Clive Best says:

    There is also something else very strange about RCP8.5 and that it the value of 8.5 watts/m2 for the net forcing achieved in 2100. This emission scenario “business as usual” results in CO2 concentrations reaching about 900 ppm by 2100. However 900 ppm results in a CO2 forcing of only 6 watts/m2. The CO2 forcing I assume that models have been used to calculate that this scenario results in a final net forcing of 8.5 W/m2. They are assuming that the rest is due to other GHGs (methane, NCO, CFC). They are also assuming that aerosol negative forcing is small unlike the case today where it offsets completely the other GHGs.

    To get such high values for other GHGs I am sure you are right that they must rely on coal being the dominant fuel to an unrealistic extent. Of course RCP8.5 is supposed to be the big stick to warn governments to mend their ways or he’ll fire will ensue! I think you are right that they have overplayed their hand and this scenario is physically impossible!

  2. philsharris says:

    I am from UK – I raised with Euan yesterday in Blowout wk 16 the interesting prospect of coal bed methane (CBM) from deep drilling in Central Scotland and have noted his reply (thanks Euan). There are resources of coal below or beyond historical mining e.g. under North Sea. CBM must be a minor part of the un-mined carbon reservoir, but are there possibilities – gasification and other ‘robotic’ mining that might give unprecedented access to reserves and then to ‘resources’? It sounds very unlikely to me on (un)economic grounds, but what do I know?

    I did a back of envelope calculation recently comparing Aleklett (Peaking at Peak Oil, 2012) and Gillett, 2011;
    Aleklett uses historical mining data and Gillett relies on IPCC et al emission scenarios. Coal has a large relevance to the following projections. The resulting CO2 in the atmosphere because of different emission assumptions by the authors differs markedly both in peak and long term conjectured concentration. ‘Unconventional coal’ though just might make a difference?

    At the present time carbon emission continues to rise and thereby to cause the atmosphere’s accumulated CO2 (as parts per million; presently 400ppm) also to rise – albeit at a slower yearly rate than the emission: (See Gillett’s Fig.1).
    I have attempted to translate into the units used by Gillett, the projection by Aleklett of total fossil carbon-burn this century, and thereby to calculate the effect of Aleklett future emissions on atmospheric CO2 levels*. Aleklett supposes a further 5740Gboe (all fuels) by year 2100 producing 2330 billion tons of CO2. Taking Gillett’s assumption of 500Pg of carbon emitted to date, I calculate a further 874PgC, making accumulative emissions of 1374Pg carbon by year 2100 (Aleklett), compared with Gillett’s assumed emission of 2200PgC.
    Using Gillett’s ratios of net carbon remaining in the atmosphere (after absorption of C by both ocean and terrestrial surfaces), I see a peak level of CO2 in the atmosphere circa year 2100 of about 550ppm. According to Aleklett using his own (low side) numbers, there remains a probability (perhaps 25%) that mean global temperature will exceed the UN target of staying below a 2°C rise.
    NB *Aleklett does not provide a number for peak CO2 parts per million in the atmosphere. I am using his emission numbers as a ‘lower bound’ scenario. Of course some fossil fuel burn, particularly coal, will continue after 2100 in Aleklett scenario even when the rate of burn is much depleted. He projects substantial coal annual production still being burned in the 22ndC.

  3. Oldfarmermac says:

    Every body who follows such arguments knows they are academic rather more so than not when taken to extremes.

    I will not argue that it is impossible that we will burn continue to burn coal in increasing quantities for another century because it may be possible to find ways to mine it cheaply enough or as somebody else has mentioned we may manage to burn it underground.

    But the cost of it in plain old sweat and capital is going to be going up every year as the quality of the resource gradually declines.

    I am not a technocopian or a happy go lucky economicist who believes energy can be manufactured but I do have a great deal of respect for Adam Smith’s Invisible Hand and scientists and engineers. And economists do know a few things even if they generally don’t know the abc’s of the physical sciences.

    It is almost a sure thing that renewable energy will be cheaper on a dollars and cents basis in a couple more decades than coal- never mind the climate question for the moment.

    We will find it cheaper to economize on the energy we get from coal than we do to pay for it.

    Building codes will be tightened up in a draconian fashion by energy importing countries for instance to the point that new construction needs very little heat.

    LED lights will totally displace fluorescents and incandescents within a decade or not much longer.

    Steel and aluminum will be recycled at astonishing rates as will glass and other energy intensive materials that are currently mostly landfilled will be recycled in the not too distant future.

    And governments everywhere will eventually find it necessary to institute across the board energy conserving regulations that will change the ways we live in ways that are barely on the radar screen even of the most ardent conservationist. If they don’t the market will do it for them anyway.

    People will learn to live with cars that have only a hundred mile driving range or even less if the battery industry can’t provide more range at an affordable cost.Sales people are capable of coming up with innovations-if I were a sales manager with Nissan today I would be working out how many gasoline cars I would need available as free loaners or dirt cheap rentals for Leaf customers who are going to need them to make long trips a few times a year.

    HVDC power lines and wind and solar farms aren’t exactly cheap but they will be choices economical in the future when coal and natural gas are more expensive.

    And the throw away society may actually be outlawed.I am if I say so myself very broadly skilled in repairing various mechanical items and there is no doubt that most things we scrap are in need of only very minor repairs compared to the cost of replacement.

    IF a manufacturer of washing machines for instance were to be compelled to warrant them for say five thousand loads or ten years and guarantee replacement parts for twenty years it would cost almost nothing in comparison to the cost of building a new washer from scratch and getting it from the factory to the end user.

    This sort of regulation would save an enormous amount of energy and resources over the years but of course the manufacturers and retailers would scream bloody murder about such rules.Nevertheless they may be inevitable once the fecal matter is well and truly in the fan.

    Now back to the climate- we are going to fry well before we ever burn half as much coal as projected unless there are some powerful unforeseen feedback loops that counter act the insulating effect of all that co2.My own wild guess is that the chances of such loops existing is negligible.

  4. cassandraclub says:

    On her blog “Our Finite World” Gail Tverberg also concludes that the RCP8.5-scenario is unrealistic. The RCP6.0 scenario of the IPCC is very unlikely.
    Why worry about the warming of the atmosphere when can worry about the end of oil instead? 😉

  5. Roger Andrews says:

    Yet another problem with the RCP 8.5 scenario is CO2 residence time. How long does the CO2 emitted by fossil fuels remain in the atmosphere before being absorbed by vegetation or the oceans?

    I have developed an empirical model which gives a close fit to observations at an e-folding time (the time for a slug of emitted CO2 to decay to 1/e of its original concentration) of 48 years, as shown in the first graph on the attachment. (Note that 38 and 58 year don’t fit.)

    The IPCC, however, uses “residence times” (mathematically equivalent to e-folding times x 0.69) of hundreds or even thousands of years. As a result I need e-folding times of around 100 years to get an approximate fit to the IPCC’s RCP 8.5 CO2 concentrations (second graph).

    But when I apply my 48-year best-fit e-folding time I get CO2 concentrations in 2100 that are about 200 ppm lower than the IPCC’s numbers (third graph. Note how the 48-year CO2 plot begins to curve back when emissions begin to flatten out after 2070 while the IPCC plot continues to go straight up.)

    Based on these results I’m going to say that the IPCC’s inflated CO2 residence times add at least another spurious 50% to the IPCC’s 2100 CO2 concentrations. Combining this with the doubling (at least) caused by the mining of non-existent coal reserves and the ~10% added by the evident miscalculation of forcings leaves us with RCP 8.5 * 0.9 * 0.67 * 0.5 = RCP 2.56, enough to cause a surface temperature increase of about 0.7C. Assuming, that is, that CO2 concentrations have an impact on surface temperature, and there seems to be some doubt about that too. 😉

  6. Luís says:

    Great to see Dave Rutledge around. One important trend completely ignored by the IIASA is the increasing share of sub-bituminous coal in total coal production. When they project a threefold increase in CO2 emissions from coal they are actually projecting a fourfold increase in extracted volumes. From where will all that coal come? At what cost? And with what environmental impacts?

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