I have been listening on Econtalk, a podcast production by economist Russ Roberts, to an interview with Matt Ridley, who calls himself a “lukewarmer” regarding climate change (by the way, I highly recommend Econtalk). To be a “lukewarmer” is to believe climate change is probably man-made, but not dangerous. Now before I get criticisms for being a climate skeptic, I concede that science is not settled, despite what climate advocates argue. The two positions on either side of the spectrum are the climate skeptics, who believe there is no man-made climate change and the climate advocates, who insist that climate change is real and man-made. Ridley says is may exist and may be man-caused, but that it likely is not dangerous and may even be beneficial. These positions themselves provide evidence that the science on this issue is most surely not settled. Continued research is needed, to be sure. But let’s not allow ad hominem attacks to stifle real and objective research.
Now let’s get down to the details of the science first. The famous “hockey stick” graph, so crucial in driving the argument for the existence of man-made climate change, was based on faulty research, whether intended or not. Several different data sets were used in the study leading to the graph, including one that measured change based on the proxy measure of how fast tree rings grew. Remember, we were not walking around with thermometers centuries ago, or even 150 years ago, so we have to have some substitute measurements. Tree rings grow faster as climates get warmer. Here is how Ridley explained it:
The hockey stick is a chart of temperatures over basically the last thousand years. Produced in the late 1990s and based on so-called proxies. Now that means–you obviously can’t go back and measure the temperature in, you know, Arizona or in 1420 because no one was walking around with a thermometer there. But what you can do is look at the width of tree rings. And if you make the assumption that trees are growing faster in warmer temperatures, then you can say it was warmer then or it was colder then, and you can produce a chart. And if you combine lots of these proxies, you come up with a rough estimate of temperature over the last 1000 years. And what it appeared to show was a sort of gentle cooling for most of that time, followed by a very rapid warming in the last 50 or 100 years.
Now it turned out that there were two things badly wrong with it. One was that many of the data sets, the most dominant data set of all, was from bristlecone pine trees in the American West, which had been explicitly gathered by scientists who knew they were measuring a different phenomenon, namely the fact that overgrazing in that area had caused tree bark wounds, which resulted in rather rapid growth as the tree tried to cover up the wounds if you like–of course stripped bark. But any way, the point was nobody who was actually measuring the tree rings of bristlecone pine trees thought that bristlecone pine tree ring width reflected temperature. So that data shouldn’t have been used. And I’m simplifying a bit here–there’s a lot of other details and a lot of other data to discuss. But the second problem, if you like, was that the statistical filter through which the data was passed, called short-centering, resulted in any data series which showed a 20th century optic being vastly exaggerated. Being able to influence the final outcome more than a hundred times. In other words, the statistical method was–and this was beautifully demonstrated by Ross McKitrick and Steve Macintyre, Canadian economist and mathematician, basically, who were incredibly diligent in tracking this down. And they showed that actually this method was fishing out any data with a hockey stick shape and giving it undue emphasis. So, what happens if you leave the bristlecone pines out, and one other paper from the Gaspé Peninsula in Canada? And the answer is if you do that the hockey stick disappears altogether. Now, this was known to the scientists doing the work, because they’d actually done that; and they accidentally revealed this when they sent a data file called ‘Censored’ into the public domain, which showed that they had discovered that without those two data sets they couldn’t get a hockey stick. Now, you don’t have to get lost in the details of this or start accusing people of malfeasance, which I’m not doing here. I’m just saying that this one incredibly influential graph–and it was influential, not only on me but on the world: it was used 6 times in the Second Assessment Report of the IPCC; it was displayed at the Press Conference when the Report was announced. It was a fantastically important chart. This chart was based on data which–you only had to take one data set out and the chart changes completely. Now, for me, that’s a real alarm bell. That tells you that–you are potentially contaminating your conclusions with very, very suspect data. There were further attempts to sort of rescue the hockey stick which involved large trees from Siberia. And again, when you drilled down, it turned out that there was one incredibly influential larch tree in the sample. One tree.
Now you have to read this pretty carefully, and it is only one element of Ridley’s argument. But the upshot is that man-made climate change was accepted by so many based on the error (being most generous) that skewed the outcome drastically.
“Science is in the business of proving the experts wrong,” someone once said. So the responses to the data that was in error ought to be taken seriously, before we begin running around saying “the sky is falling.” But why? One might argue that even if the chance of dangerous climate change is extremely small, we need to take even major precautions to foreclose it. But in the process, we get to economic issues that impact real people. What happens if politicians and policy analysts (experts) begin to believe that measures to prevent possibly dangerous climate change ought to be taken despite the costs of doing so? Costs affect people, and they affect poor people proportionately more than others. Let’s take the poor in Asia. Say their leaders are convinced global climate change is dangerous and that CO2 emissions from fossil fuels must be drastically reduced. But to do so requires that the economic output must necessarily be reduced also, as the cost of the implementation of pollution reduction is immense. Now the poor are in real trouble. They cannot afford such costs. They die.
There are other questions raised by Matt Ridley about the research supporting global climate change. I will leave those to the listener. And, please, check the people and sources he mentions. Don’t take my word for it.
Finally, approaching this subject as a Christian, let me say that we are most definitely called to “take dominion.” (Genesis 1) This does not mean that we are called to destroy our environment, but on the other hand, the dominion mandate is primarily intended for human well-being in God’s gracious economy. Therefore, we must be prudent. That means we do have to take science seriously, but science itself must understand its own limits. Moreover, Christians ought not to allow activists with radical agendas to coopt the Scriptural mandate. Costs and benefits are to be considered carefully, but costs and benefits must be measured accurately and comprehensively. And we have to be careful about elevating small possible risk as the central factor, when real people’s lives are at stake. God created humans in His image and our task as environmental stewards is both to preserve and enhance our earthly home and to do so for our benefit that God might be glorified.