A Rational View of Global Warming

Not that the scientists and politicians from Al Gore to the attendees of last month's Copenhagen summit are completely without rationality, but one must admit that except for the scientist-to-scientist exchanges (and not all of them, if some recently disclosed emails are considered), ratiocination—meaning the process of reasoning from objective, verifiable facts to logical conclusions—is in scarce supply in discussions of global warming. The problem is that so much of the controversy depends on what is going to happen, as opposed to what has happened already, and no matter how good one's computer model or crystal ball, debates that hinge critically on future events tend to go on forever—or at least until the future under debate turns into the past. And by then it's sometimes too late.

How refreshing it was, then, when I found on my acquaintance Prof. David Rutledge's website a detailed presentation of his that takes an original, yet historically based approach to the question. The title is not one to grab headlines: "Hubbert's Peak, the Coal Question, and Climate Change." But Rutledge, a highly honored mathematician and engineering professor, Fellow of the IEEE, former Caltech division chair, and all-around straight shooter, would rather title a talk accurately than sexily.

The Hubbert's Peak of the title is not to be found in a mountain range, but in the statistics of U. S. oil production. In 1956, King Hubbert, an engineer with Shell Oil, wrote a paper predicting that oil production in the States was rising but would peak in about fifteen or twenty years, thereupon entering a gradual decline for the rest of the century. The entire curve, from the early Spindletop discoveries to the present day and beyond, would resemble the famous Gaussian or bell-shaped curve of elementary statistics, though for different reasons. The point is that within a given large region of exploration, discovery and production activities tend to follow a pattern that starts small, peaks sooner or later (at a time that can often be estimated from historical data), and then tapers off.

Rutledge has compiled statistics from other countries and other fields, notably regional and global coal production, which tend to bear out the general principles behind Hubbert's Peak. I have neither the space nor the expertise to do justice to this 60-slide presentation, which is obviously the tip of a larger iceberg of work which Rutledge says will eventually turn into a book. But I have managed to glean a couple of take-homes from the intimidatingly extensive and sophisticated analyses that Rutledge and his collaborators have performed.

One is, that government estimates of fossil fuel reserves, no matter by what government and no matter when, tend to be optimistic by factors of two or three. Comparing such historical estimates to the facts on the ground (or we should say, dug out of the ground, in the case of coal) shows that this principle, which Rutledge distinguishes with the name of "Deffeyes' Law of Bureaucratic Resource Estimates," prevails across national boundaries and across decades. In other words, government bureucrats almost invariably give in to political pressures to overestimate reserves.

This has important implications for the second take-away, which has to do with what will actually happen with regard to global warming as the remainder of the world's fossil fuel reserves get burned up. Trouble is, the Intergovernmental Panel on Climate Change (IPCC), the august body whose pronouncements are treated as gospel by many, uses government estimates of future production in its calculations. In one of the few slides where Rutledge lets a little emotion show through, the title is "Where Does the IPCC Get Its Coal Numbers?" He shows how the IPCC cherry-picks the worst-sounding bureaucratic estimates in order to get their input numbers for their climate analyses. On the following slide, "Carbon Dioxide Emissions" he shows his piece de resistance: a chart of the many and various IPCC estimates of cumulative CO2 emissions versus time out to 2100, compared to his own statistics on the question. The IPCC curves spray out high into the graphical sky, like tracers from a crazed machine-gunner trying to shoot down an invisible fighter plane, while Rutledge's curve slowly and gracefully slides in underneath them all like a gently rolling hill.

The bottom bottom line, on his summary slide, is that according to his figures, based not on speculative climate-change models but simply on historical production figures, rationally interpreted, is that we are not going to end up burning nearly as much carbon as the IPCC says, and that the human-caused portion of both future temperature change and ocean-level increases will be so small as to be comparable to the natural noise level.

Is Rutledge right? Again, the only absolutely sure way to tell is to wait and see, although if the issue is what happens by 2100, the waiting will have to be done on the part of my very youngest readers, or perhaps their children. But if you are looking for a calm, highly rational, technically challenging, but rock-solid study about the climate-change controversy, you could do no better than to look at what Prof. Rutledge has come up with.

Sources: The presentation referred to can be downloaded free at Prof. Rutledge's website http://rutledge.caltech.edu/, where PowerPoint slides, an Excel file, and video of his Watson Lecture on this subject are all available.