Dr. Richard Lindzen and Dr. William Gray are prominent sources for skepticism of AGW. Imagine for a moment that they were to both reverse their positions and state that, after careful re-examination of the evidence, they had concluded that AGW is real and requires some action from humanity. Would that change your opinion on the subject?
Some tension is inherent in relying on both Gray and Lindzen, given their disagreements with each other. “Lindzen’s and Gray’s arguments have been widely challenged — including by each other. Gray has referred to Lindzen’s theory as a red herring, while Lindzen has termed Gray’s grasp of the theoretical as ‘frustratingly poor'” (Prendergast). Why should someone embrace their disagreements with the vast majority of the scientific community but not their disagreements with each other?
One of Dr. Gray’s colleagues “says he’s eagerly awaiting Gray’s first peer-reviewed contribution to the discussion. Gray says he’s working on it” (Prendergast). If he had submitted a paper to a peer-reviewed journal and been rejected, one might argue that he is the victim of some scientific conspiracy. As my roommate Chris noted, that is not the case; in fact, he has not yet tried to submit a paper! This forces me to seriously question the validity of his claims.
Conservative Christian leaders “Colson and Dobson seem to understand is that it is the height of man’s arrogance to say that we can’t predict next Tuesday’s weather but we can tell ya how warm the earth will be in 2239.” The two skeptics also claim that scientists’ inability to predict the weather proves that scientific predictions of future climate are similarly unreliable. According to Dr. Lindzen, those who accept the reality of AGW assume “that our warming forecasts for the year 2040 are somehow more reliable than the weatherman’s forecast for next week” (Lindzen 2007). Dr. Gray “is wary of any methodology that claims to accurately track weather more than a few days ahead” (Prendergast). So am I, but weather and climate are two different things. The AR4 answers explains this nicely in FAQ 1.2.
“Climate is generally defined as average weather, and as such, climate change and weather are intertwined. Observations can show that there have been changes in weather, and it is the statistics of changes in weather over time that identify climate change. While weather and climate are closely related, there are important differences. A common confusion between weather and climate arises when scientists are asked how they can predict climate 50 years from now when they cannot predict the weather a few weeks from now. The chaotic nature of weather makes it unpredictable beyond a few days. Projecting changes in climate (i.e., long-term average weather) due to changes in atmospheric composition or other factors is a very different and much more manageable issue. As an analogy, while it is impossible to predict the age at which any particular man will die, we can say with high confidence that the average age of death for men in industrialised countries is about 75. Another common confusion of these issues is thinking that a cold winter or a cooling spot on the globe is evidence against global warming. There are always extremes of hot and cold, although their frequency and intensity change as climate changes. But when weather is averaged over space and time, the fact that the globe is warming emerges clearly from the data” (Somerville, et al.).
Many skeptics cite fears of Global Cooling from the 1970’s as evidence that climate science is untrustworthy, computerized climate models are unreliable, and current warnings of AGW should not be taken seriously. However, atmospheric scientist Dr. Jerry “Meehl says the models have helped explain one of the great climate mysteries of the twentieth century. The earth warmed significantly in the first five decades of the century, then cooled until the mid-1970s. The industrialized world was pumping out increasing levels of greenhouse gases during the latter period, so why wasn’t the temperature increasing? The answer, researchers concluded, was that increased industrial pollution after World War II blocked solar radiation, lowering temperatures and prompting some short-lived speculation about a coming ‘ice age'” (Prendergast).
In other words, the cooling trend was real, and it was caused by human behavior, specifically the pollution of the atmosphere by aerosols like soot and dust. The trend was eliminated by a change in behavior when “North American and Western European countries started cleaning up their emissions,” which “reduced the load of the aerosols while the greenhouse gases were relentlessly increasing, and it’s been warming ever since” (Prendergast; see Somerville, et al.). Interestingly, that change in behavior was made for reasons completely disjoint from the cooling trend. AGW is also real, also caused by human behavior, and also can be ameliorated by a change in human behavior.
When I asked what evidence of AGW would be convincing, the response was, “If it were solid, scientific evidence (rather than the tripe currently trotted out as ‘undeniable’ fact), I would much more seriously consider it.” That is not an answer to my question. It is an accusation against Al Gore and the scientific community of fraud for political gain, ignoring evidence, and conspiring to suppress unwanted data and doubting scientists. So, I ask again in the hope of actually receiving an answer. What experiment could be performed, measurement made, observation reported, or evidence gathered that would not be comparable to an animal’s stomach?
The response to my question about what would be necessary to convincingly demonstrate the sincerity of AGW experts begins with “the fact that sincerity has no effect on veracity.” That is correct, but sincerity does affect the type of accusation directed towards the scientists. If they are sincere, a skeptic should accuse them of incompetence. If they are insincere, a skeptic should accuse them of fraud. Given the repeated statements that the flaws in AGW are so obvious that non-scientists can spot them and the claim that “doubting scientists [are] being fired and de-funded for speaking their minds,” your accusation against the scientists is apparently outright fraud. That is not an accusation to be made lightly; proof of deliberate fraud will end the career of a scientist, as vividly demonstrated by the case of Hwang Woo-Suk.
Contrary to those accusations, Dr. Lindzen has not been silenced or fired; he is still a professor and member of the National Academy of Sciences, which is the most prestigious scientific body in the United States. I met him in 2003 when he came to Ohio State to give a colloquium on global warming; he presented the week before Dr. Mann. Before the colloquium, I had lunch with him, another professor and several other graduate students.
Your blog entries accuse climate scientists of fraud when they scientifically test hypotheses about AGW because, “To scientifically test something, you need a closed, controlled environment. Last time I checked, the atmosphere and related stuff such as the earth and space are about as open and uncontrolled of an environment possible.” A closed, controlled environment is the ideal setting for scientific testing, but it is not the only one. The AR4 explains further in section 1.2.
“A characteristic of Earth sciences is that Earth scientists are unable to perform controlled experiments on the planet as a whole and then observe the results. In this sense, Earth science is similar to the disciplines of astronomy and cosmology that cannot conduct experiments on galaxies or the cosmos. This is an important consideration, because it is precisely such whole-Earth, system-scale experiments, incorporating the full complexity of interacting processes and feedbacks, that might ideally be required to fully verify or falsify climate change hypotheses….Nevertheless, countless empirical tests of numerous different hypotheses have built up a massive body of Earth science knowledge. This repeated testing has refined the understanding of numerous aspects of the climate system, from deep oceanic circulation to stratospheric chemistry. Sometimes a combination of observations and models can be used to test planetary-scale hypotheses. For example, the global cooling and drying of the atmosphere observed after the eruption of Mt. Pinatubo (Section 8.6) provided key tests of particular aspects of global climate models” (Somerville, et al.).
Does the assertion that the nature of “atmosphere and related stuff such as the earth and space” make scientific tests impossible contradict the claim that “solid, scientific evidence” would be worthy of serious consideration? In other words, has solid scientific evidence not been presented, or is it impossible to obtain? If it is the latter, then no scientific evidence could convince a skeptic that AGW exists.
Another accusation is that scientists ignore “other OBVIOUS and documented likelihoods, such as that the earth has been cyclically warming up and cooling down since it was formed many years back and is just currently in a warming period.” According to this article, rather than accepting these cyclical temperature fluctuations, “the post-Christian West seems to have decided that, if the here and now is all there is, then we have to keep the here and now right here and exactly as it is now for all time.” Dr. Lindzen alleges that a “general characteristic of Mr. Gore’s approach is to assiduously ignore the fact that the earth and its climate are dynamic; they are always changing even without any external forcing” (Lindzen 2006).
The sun, volcanic eruptions, shifts in Earth’s orbit, and other natural factors do affect the climate; I know of no serious scientist who has claimed otherwise. However, contrary to Dr. Lindzen, these are all external forcing. This is especially obvious in the case of the sun, which can hardly be considered to be internal to Earth’s atmosphere. Earth’s climate does change over time, but this shows that the climate system is susceptible to external influence. Climate researchers have strong evidence that human activity is becoming a new and very important force affecting climate.
Scientists have noted that changes currently being attributed to human influence are qualitatively different than the variations documented in the geological and historical records. “It is very likely that the global warming of 4°C to 7°C since the Last Glacial Maximum occurred at an average rate about 10 times slower than the warming of the 20th century” (Jansen, et al.). Under the IPCC definitions, “very likely” means greater than 90% probability. In other words, we are heating up the planet 10 times faster than natural variations have done during the past few millennia.</font>
Another difference between the prehistoric world and the modern one is that millions of people were not living near or below sea level before the Last Glacial Maximum. So, scientists are not, as Dr. Lindzen alleges, making “the false assumption…that we live in a perfect world, temperaturewise” (Lindzen 2007). They have noted that AGW, especially at these rates, will have a much greater impact on human civilization than past natural climate changes.
The most serious accusation made against climate scientists is that they have abandoned the scientific method. The basic steps in the scientific method are Observation, Hypothesis, Predictions, and Testing. Actually, multiple hypotheses are often advanced, and some or all of them are eliminated by tests. AGW satisfies this method, and I shall examine two examples. The first assesses the scientific validity of the claim that humans are responsible for increasing concentrations of CO2 in the atmosphere; it is primarily taken from Francey et al.
Observation: CO2 concentration in the atmosphere is 379ppm, and has increased from 280 ± 20 ppm in 1750. (Somerville, et al.)
Hypotheses: According to mainstream climate science, human burning of fossil fuels is responsible for the excess. I shall call this the anthropogenic hypothesis.
According to your blog, “There is no consensus regarding humanity’s involvement in the increased CO2 levels.” Instead, “there are some other natural reasons for the uptick in carbon dioxide.” Specifically, as “the post-glacial thaw progresses, the oceans warm up, and some of the dissolved carbon emits into the atmosphere, like fizz from soda.”
Predictions: Plants preferentially photosynthesize the lightest isotope of carbon (12C), which contains six protons and six neutrons. Heavier isotopes are present and nature that contain seven (13C) or eight (14C) neutrons; these are less easily absorbed by plants. These preferences lead to fractionalisation, which increases the ratio of heavier to lighter isotopes.
Oil and coal are ultimately derived from plant matter, so combusting them will produce CO2 with an altered isotopic ratio. “In contrast, the fractionalisation associated with diffusion across the air-sea interface is an order of magnitude smaller” than that caused by photosynthesis. The isotopic ratio of CO2 produced by human burning of fossil fuels or biomass will be measurably different than CO2 bubbling out of the ocean.
Using this definition, we can make predictions. If the increase is due to oceanic release of CO2, δ13C should be constant over time. If the increased concentrations of atmospheric CO2 are anthropogenic, the increased concentrations should be accompanied by a decrease in δ13C beginning at the start of the industrial era in the late 1700’s or early 1800’s. Further, δ13C should decrease with increasing CO2 concentration.
Testing: Measurements of the ratio in tree rings, ice cores, and coral reefs are summarized in the following graphs.
A major allegation raised by both skeptics is that “we do not understand the natural internal variability of climate” (Lindzen 2006). Therefore, Dr. Gray is “convinced that the climate is far too complicated for even the most powerful computers to forecast accurately years in advance” (Prendergast). As I recall, the primary point of contention between Dr. Lindzen and Dr. Mann in their colloquia was the reliability of computer climate models. Alexander Cockburn more bluntly asserts that “greenhouse fearmongers rely on unverified, crudely oversimplified models to finger mankind’s sinful contribution.” The accuracy of these models is a legitimate and important topic, and it is the bases of our second example of the scientific method in action.
Observation: Global average temperatures rose 0.6 degrees C between the beginning of the industrial era and 1998 (Lindzen 2007), and they continue to rise.
Hypotheses: According to Drs. Gray and Lindzen, this increase in average temperature is solely due to natural variability.
According to the IPCC, this increase is primarily due to human activity.
Predictions: Dr. Gray predicts “that within a few years the earth will begin to cool again” (Prendergast) Specifically, he predicts Earth will begin cooling “in the next 5-10 years.” Computer models predict that if current trends in human activity continue, Earth will continue to warm for at least the next century.
If global average temperatures are higher in 2017 than they are now, will that change your opinion of AGW? Answers can be provided in words here or in dollars on Long Bets. However, we need not wait that long to test the predictions of computer models.
Testing: The figure below is taken from Somerville, et al. The blue, green, and dark yellow bands show the predictions made by computer models for the first (FAR), second (SAR), and third (TAR) reports of the IPCC. The blue band shows the predictions made by relatively simple versions of these models in 1990. The black points show the actual observed global average temperature from 1990 through 2005, relative to the mean of the 1961 to 1990 values. The black line “shows decadal variations obtained by smoothing the time series using a 13-point filter,” which is similar to a running average.
The upward trend predicted by the models is verified. The observed average is almost always within the predicted range. These models are intended to predict long term trends rather than the average temperature in any individual year. In that respect, this model does well.
Regardless of any criticism, incredulity, or accusations of oversimplification, these results show that the relatively unsophisticated models of the late 1980’s correctly predicted global temperature trends for the next 15 years. I think we can reasonably expect the more sophisticated models and computers developed since then to make more accurate predictions.