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Crichton's 'Aliens Cause Global Warming'

Posted on 8 February 2011 by Alden Griffith

In 2003, Michael Crichton delivered a lecture at Caltech titled "Aliens Cause Global Warming". This lecture has since circulated widely and its arguments often come up in critiques of climate science. An excerpt was even published posthumously in The Wall Street Journal. I wish to comment briefly on two particular sections of the lecture: consensus and climate models.

On Consensus...
Although he never defines exactly what he means by "consensus", Crichton's use of the term seems to rely on a limited and largely incorrect view of the scientific process. He attempts to portray the idea of consensus as irrelevant in science, and assumes that all of science boils down to clear, proven facts: "Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant." Unfortunately, complex scientific topics do not fit this "neat and simple" model at all. Climate science is an amalgamation of many different investigators, examining many different lines of evidence that lend strong support to the conclusion that humans are modifying the climate system. This extensive field of research cannot, and will not, ever come down to one investigator being right or wrong. In this case, the vast majority of climate scientists agree on several main conclusions that only emerge with the synthesis of many independent lines of evidence. The reality of climate science is that no single piece of evidence can solely support or refute the conclusions that have emerged. This is exactly why the concept of consensus is important - consensus emerges to indicate what is currently understood and what is not. Rather than being irrelevant as Crichton suggests, consensus is a real and fundamental part of science.
Crichton then argues that scientific consensus has a poor track record and points to examples where the "consensus" was eventually overturned. The implication is that the consensus isn't always correct. But none of his examples are good analogues for the current consensus on climate change. Previously held views on fever, diet, and geology were not based on a robust, mechanistic understanding of empirical evidence, and often rested upon long-held assumptions that had not, or could not, be formally tested. For example, the dominant paradigm in geology going into the 19th century was largely drawn from Biblical accounts of Noah's Flood. In the mid 19th century, Charles Lyell challenged this view with a theoretical framework of more gradual change based upon extensive observations. In the 20th century, Alfred Wegener's theory of continental drift was indeed controversial at first, not because the consensus failed to "acknowledge what any schoolchild sees", but because he did not have a robust mechanisms for why the continents should move, nor was there any evidence that the continents were indeed moving. With the accumulation of more independent lines of evidence and the development of a more mechanistic theory, the consensus around plate tectonics was eventually formed (even before the movement of continents was empirically observed). In his simplistic portrayal of consensus, Crichton fails to see that the processes that formed the current paradigms in medicine and geology (and overturned the old ones) are same processes that have formed the consensus on climate change. The consensus used to be that human activity is too insignificant to alter the climate. Science advances and things change.
Finally, Crichton states that "consensus is only invoked in situations where the science is not solid enough." He revisits his idea that science boils down to clear "yes or no" answers by suggesting that it's obviously unnecessary to invoke consensus around something like E = mc2. According to Crichton, this is apparently real science with a right answer. Again, this is not very analogous to something like climate science, but it's also not a valid example in its own right. Einstein originally proposed the idea of mass-energy equivalence largely based on theoretical ground and without strong direct empirical evidence. Support grew around the theory, but if you wanted rock-solid "proof", you probably would have had to wait almost three decades until the discovery of the positron (the observed conversion of energy into matter and antimatter). While it currently may seem silly to think of there being a consensus around E = mc2, there was a time when this "fact" needed to build up its own evidence and consensus. And in contrast to climate science, this particular case does largely boil down to a relatively straight-forward test that can convincingly support or refute the theory. Crichton's broader implication that all of climate science needs to be 100 percent "solid" is really a strawman argument: an impossible version of reality that is therefore easy to pull apart. Instead of indicating science that's not solid, the consensus on climate change informs us which aspects are solid and which are less so.
On Climate Models...
Crichton's only direct critique of climate science in the lecture is the "overt reliance that is being placed on models". This is a version of the common claim that the evidence for global warming is based on computer models. Unfortunately, this claim is not true. Climate models are one among many tools and methodologies used in climate science. They are extremely useful for certain applications (especially in predicting future climate), but the conclusion that humans are significantly contributing to climate change through greenhouse gas emissions would remain robust in the absence of computer models. To hold them up as the keystone of climate science is another strawman argument.
Even still, Crichton's critique of climate models is off base, starting with his confusion of weather (which is chaotic) and climate (which is not). Most importantly though, climate models do not attempt to "predict the world of 2100," but instead project different climate scenarios based on a range of assumptions of what the world might look like in terms of population, greenhouse gas emissions, land use patterns, etc. Their assumptions, caveats, and uncertainties are openly discussed. In the absence of computer models, we can still make valid probabilistic projections of mean global temperatures based on future greenhouse gas concentrations (it will get warmer). However, without climate models we cannot have any real sense of regional differences, particularly with regard to precipitation. Climate models thus provide a very important means of examining potential local impacts of climate change, but they are far from the the keystone of consensus that Crichton implies.
Aside from his discussion of consensus and climate models, Crichton builds an indirect case against climate change science based on guilt by association, although he never convincingly demonstrates association, nor guilt. It is a tremendous logical leap of faith to conclude that the search for extraterrestrial radio signals and one group of scientists' research on the potential impacts of nuclear war somehow invalidate decades of climate research by thousands of individuals. Overall, Crichton's lecture is primarily supported by his rhetorical skills, not his arguments.
Another take on Crichton's speech with more examination of some of the facts he presents can be found here.

Other presentations by Alden Griffith can be found at Fool Me Once.

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Comments 51 to 59 out of 59:

  1. #49 Dikran Marsupial at 03:54 AM on 15 February, 2011 nice attempt to distract attention from the fact that you had used a regional trend to try and refute a claim about global trends NH extratropics is quite some region. However, if you have global data going back to several millenia with annual resolution, just drop a link. That way anyone can see your point. Otherwise it is Argumentum ad Ignorantiam once again. You basically say as we do not have global data for 950-990 AD, it proves global trend was different. As to Argumentum as Ignorantiam, that would be true if I had said that the AGW hypothesis rests solely on the fact that we can't explain the current warming without AGW, but I didn't write that. Instead I wrote that there was a known mechanism with good support from experiments, observation and theory. You are right. Based on that knowledge would you please explain to all why global SST increased between 1910 and 1940 at a 0.165°C/decade rate, dropped by 0.24°C during the next decade, then increased again at a rate of 0.1°C/decade ever since?
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  2. Is there any reason why the ocean's "sea level" is not a good proxy for describing average global temperature, going back 10,000 years? Shouldnt there be a direct relationship between the total water line and overall temperature? And taking this just a tad further, I would ask if there be any proxy around that can mark the rate of such changes? If so, I guess maybe someone could know if climate had ever changed so fast in the past, or could theoretically change even faster due to some natural occurrence. And what exactly justifies the assumption of linear and or continuous climate models, there being many natural phenomenon that are sporatic and intermittent? An observed change may just be a fluke of natural variation not unlike a hurricane that has a beginning and an end.
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    Moderator Response: [Daniel Bailey] As always, please use the Search function to find an appropriate thread where(far more likely than not) these questions have already been dealt with here at SkS. You already know this, RSVP.
  3. BP, The standard explaination for the flat curve between 1940 and 1980 is sulfate aerosol pollution counteracting the warming from CO2. You certainly know that. When the west cleared up sulfate pollution (to counteract acid rain), it started to heat up again. It is not even worth me providing a link. What is your point anyway? Have you given up on trying to find data that supports your position and now you argue that no-one knows anything,it is all "Argumentum ad Ignorantiam"? You will have to forget a lot of the data in the IPCC report to do that.
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  4. BP@51 NH Extratropics may be a large region, but it isn't global, so you can't logically use it to refute an argument about global temperatures. I am not making an argumentum ad ignoratium regarding warming rates, as the only statement I have made on the subject is that the recent warming rate (since the 1970s or so) is not particularly unusual. Given that the 1910-1940 warming ocurred at a not too disimilar rate, why is this such a surprising statement? Besides, did you not read the bit in my post where I said Marcus was quite possibly wrong on that particular point? BP wrote "You are right. Based on that knowledge would you please explain to all why global SST increased between 1910 and 1940 at a 0.165°C/decade rate, dropped by 0.24°C during the next decade, then increased again at a rate of 0.1°C/decade ever since?" You could always try reading the IPCC WG1 scientific basis report, which addresses that point (I would give you a page number, but I am out of the office at the moment). The rise 1910-1940 in global temperatures is attributed to solar forcing, the mid century dip in temperatures are thought to be due to aerosols as michael sweet pointed out. Both the greenhouse effect and aerosols will affect sea surface temperatures as well as air temperatures. Downwelling IR will warm the surface waters just as they warm anything else. BTW is there any reason for plotting a graph of sea surface temperatures, rather than global temperatures?
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  5. #53 michael sweet at 07:13 AM on 15 February, 2011 The standard explaination for the flat curve between 1940 and 1980 is sulfate aerosol pollution counteracting the warming from CO2. You certainly know that. I do. I also know it can't be true. According to the Hadley Centre SST reconstruction above (based on Rayner 2006) the curve is not flat between 1940 and 1980. It drops sharply between 1940 and 1950, but between 1950 and 1980 it has the same general upward slope (0.1°C/decade) as it has after 1980. No one cleared up pollution in the 1950s. Anyway, Marcus' claim of a recent +0.16°C/decade warming expressed under #37 exaggerated. There was a sizable jump in the second half of the 1990s, but since then lower tropospheric temperature anomaly trend above the oceans is practically flat. Huge volcanic eruptions like El Chichón or Pinatubo clustering in the first half of the last three decades explain this feature.
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  6. #55: "Marcus' claim of a recent +0.16°C/decade warming expressed under #37 exaggerated." False. See multiple prior threads here which verify that figure. Since you are okay with selecting a region and calling it global, see the thread on recent NH warming: +0.3 degrees C/decade. "since then lower tropospheric temperature anomaly trend above the oceans is practically flat ... El Chichón or Pinatubo clustering in the first half of the last three decades explain this feature." How so? The cooling associated with Pinatubo was finished by '93. See the temperature graph in #50.
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  7. BP @55, Why are you cherry picking February 1997 as a starting point? And you know very well that calculating trends for periods less than 20 years or so years is a no-no. And why do you focus only on lower tropospheric above the oceans? Note too that the RSS product doesn't include the poles (i.e., does not reflect polar amplification). Where did you source that graphic? Let me see, read the text here. What the...? Anyhow, how about we look at all the data BP. GIven that you chose temperatures above the oceans, allow me to show you the HadSST data record. The long-term rate of warming is 0.16 K per decade as shown by Marcus, not to mention several other datasets, see here. There was definitely a slow-down in the warming between 1945 and 1970. You claim that "I do. I also know it can't be true" referring to the aerosol loading hypothesis. Can you actually support that assertion with with some facts? Otherwise you are just arm waving.
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  8. #56 muoncounter at 08:59 AM on 15 February, 2011 see the thread on recent NH warming: +0.3 degrees C/decade False. If you take the 20N - 82.5N region from RSS_Monthly_MSU_AMSU_Channel_TLT_Anomalies_Land_and_Ocean_v03_3.txt, that is, lower tropospheric temperature anomalies for NH Extratropics, the trend for the full 32 years of satellite record is 0.23°C/decade while for the last 14 years it is 0.06°C/decade. Of course you can also pick cherries. For the last 19 years (since February 1992), it is 0.3°C/decade indeed. Mt. Pinatubo erupted on June 15, 1991 and it took some time for the cooling to take effect. It all depends on what you mean by "recent", you see. But according to Gilbert 2009 oceans alone determine land temperature, so it makes sense to consider temperatures only there. If there is a significant CO2 effect, it has to raise sea surface temperature first. However, it is not easy, as thermal IR radiation penetrates less than 1 mm into the sea, which in turn is several million times deeper than that.
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  9. #58: "while for the last 14 years it is 0.06°C/decade. Of course you can also pick cherries." Interesting juxtaposition. We're supposed to make a significant conclusion from a 14 year trend now? "Pinatubo erupted on June 15, 1991 and it took some time for the cooling to take effect" That's odd. Even Spencer shows it was done within 3 years. "oceans alone determine land temperature" Interesting contradiction, there. Compo's (Gilbert's his first name) models (and who believes those?) show that warming oceans warm land: the recent oceanic warming has caused the continents to warm through a different set of mechanisms than usually identified with the global impacts of SST changes. It has increased the humidity of the atmosphere, altered the atmospheric vertical motion and associated cloud fields, and perturbed the longwave and shortwave radiative fluxes at the continental surface. That makes the case for strong positive water vapor feedback (which I believe you and others are on record as doubting). But as you say, "thermal IR radiation penetrates less than 1 mm into the sea". And of course, you've railed numerous times against the lack of evidence that oceans are warming. So how exactly is this ocean warming that Compo requires to warm adjacent land occurring? And since there's ample evidence of land warming faster than oceans, how do these model results fit the real world? Note that there's an existing thread, Why ocean heat can't drive climate change.
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