This letter first appeared in the The College Voice on 11/9/07 and 11/16/07.
I would like to thank Mr. Krogh-Grabbe for his very thoughtful response (Oct. 19, Voice) to my letter. He raises some interesting issues to which I would like to respond.
First a few comments about the nature of science. I am glad he understands that no idea in science is ever fully proven. However, I believe he places too much emphasis on the idea of “consensus” and also authority as the indicator of scientific “truth” as opposed to what I think is the real nature of science: that of overwhelming experimental data supporting a theory. Nature doesn’t really care what the consensus of scientists is at any moment; that consensus has been shown to be completely wrong many times in the history of science. Instead, it is up the scientist to evaluate every piece of data and see if it fits or doesn’t fit with the current hypothesis. If it doesn’t fit then the hypothesis must be re-examined. A simple example: the overwhelming data is that objects near the earth’s surface accelerate at 9.81 m/sec^2. You, or any else, can do the experiment and the result always seems to be the same. However, if there was one person who came up with the value of 7 m/sec^2, and it was repeatable, then the scientific community would have to reevaluate their notions of why we predict 9.8 m/sec^2 as the correct number. In the case of human-induced climate change, there is much more than one piece of evidence pointing towards explanations other than human influence. Those who support the idea of human influence as the primary cause of the current warming must respond, in a scientific argument, to that contrary data. Mr. Krogh-Grabbe is not quite correct to say I don’t trust the IPCC, I just think they have not properly evaluated the conflicting data which does not support their conclusions.
Let’s get down to specifics. We both agree that there is a warming trend. We also both agree that CO2 levels are rising and that a portion of that rise is due to fossil fuel burning. We both agree that the greenhouse effect exists, just look at Venus! However, Venus has a 95% CO2 atmosphere while the Earth’s CO2 percentage is 0.03% (3 parts in 10,000). The primary disagreement between us is that I contend that the solar influence is most likely a larger source of climate change than human produced CO2 emissions. Like other members of the College community I can order any non-subscription journal articles from the library and they usually arrive on my computer in a day or so. That is how I have copies of those articles that I cited. However, I will now show some of that data and how it casts some doubt on the basic hypothesis of human-induced global warming.
We both seem to agree that the climate has been warming for at least the past 5-600 years since “The Little Ice Age”; well before SUV’s. Mr. Krogh-Grabbe’s main contention seems to be that the temperature rise during the past 2-3 decades is an accelerated temperature rise and that its primary cause is human produced CO2. Take a look at the following graph (Fig. 1, from NASA) which puts into a longer term perspective the current temperature rise. Note how our current situation isn’t even close to the Medieval Warm Period.
Now, the IPCC’s position that this rise is due to human produced CO2. However, there is another other proposed mechanism of solar variation. Let’s look at several papers dealing with this hypothesis that are published in the mainstream scientific journals. In Figure 2 we see the temperature and solar variation (solid line) data from Moberg et al. Again note on the left edge the end of the Medieval Warm period, the Little Ice Age just before 1600AD, and the general warming since that time. The correlation Moberg et al show is quite striking and convincing as to the solar influence.
However, in a paper in the Proceedings of the Royal Society, Lockwood and Frohlich take much of the same data that Moberg uses and reanalyze the data and end up with the graph Mr. Krogh-Grabbe references in his article and is displayed on the link he gave to the Max Planck Institute. This graph shows no recent correlation between solar and temperature. Now, in yet another data set, this time by Scafetta and West shown in Figure 3, we see that the solar contribution past about 1970, does not correlate as well as the Moberg data does with temperature. However, Scafetta and West do attribute at least 50% of the current warming to solar influence.
And finally, we have the data of Svensmark and Friis-Christiansen which is in response to the Lockwood analysis. What is interesting about the Svensmark paper which shows a near perfect correlation of temperature with solar is that they have removed from the temperature data of the last 4 decades the influences of the El Nino, the North Atlantic Oscillation, and various volcanic events; all notorious acute disruptors of the climate.
Let’s tally the “consensus”: one for human induced warming, one for 50% human influence, and two against. As a professional scientist I find this situation fascinating in that there really is no overwhelming avalanche of data and analysis for either case. That means to me, that we have a lot more to learn about what is happening with the whole climate change business. Also, both Lockwood and Scafetta readily admit that the evidence for the solar influence being the prime mover of climate in the past is very strong. What is interesting about this position is that it requires that the sun suddenly is no longer the prime mover of climate starting around 1970. Given the historical data shown I find that a difficult assumption to make.
One final piece of data that seems timely: the paper by Soon (Figure 4) shows a strong correlation again between the sun and the Arctic temperature. Given this data it is not too surprising that the Arctic passage opened up this past summer.
I’ve already discussed Mr. Krogh-Grabbe’s reference to the Max Planck Institute, but I also need to respond to his other reference at the World Radiation Center. At first glance their graphical data does seem to show a flat trend in solar variation. However, he seems to have missed a critical sentence in their data description: “It is important to note that the model is an independent source of information for comparisons and as long as it is not used for over solar cycle time scales it provides a reliable time series for time scales of less than a year.” (emphasis mine). The model data shown is for comparison on a daily-monthly basis to the well-known 11 year solar cycle; it is not valid for decadal solar series.
Finally, Mr. Krogh-Grabbe praises, in a back-handed way, my pointing out that even hybrids come with environmental cost. I left as an exercise for the student (I am a faculty member) the energy cost of the nickel production in a hybrid. Since he didn’t bother to do the “homework” let me give the answer: the 33 lbs. of nickel in a typical hybrid, according to what I’ve calculated, invokes about a 100 gallons of gasoline energy penalty. This is obviously easily made up in about 5 tank fills with the hybrid given its relatively high mileage over the SUV. It doesn’t take into account the chemical runoff in the mining, refining, etc. of the nickel. Mr. Krogh-Grabbe might be surprised to learn that I actually think hybrids should become more widespread (SUV hybrids?) and hopefully cheaper so more people could buy them. I wonder if the Prius is a bit overpriced? Nah, that would mean Toyota might be interested in making a large profit. In fact, I would like to see the entire U.S. ground transportation system be totally petroleum-free. The problem is that that there doesn’t seem to be viable alternative (i.e. new energy source) that can handle the job. My reason for wanting this has nothing whatsoever to do with climate change, but I think it’s interesting that we both would like to see the same end result.
Michael Monce, Professor, Physics