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Into the Denier Den
Tony Noerpel
“If you have ever walked barefoot through a seaside mudflat, you’ve felt the mud squishing up through
your toes, and perhaps saw bubbles forming as your feet sank into the mud. The bubbles are methane.”
– Donald Canfield, Oxygen, a four billion year history, Princeton, 2014.
A friend asked if I was familiar with an ecologist named Daniel Botkin and his book The Moon in the
Nautilus Shell. It was a book club selection and my friend was curious why Botkin was agnostic about
human-caused climate change (anthropogenic global warming, AGW); was Botkin a denier, a skeptic or
correct about the science? I replied that if he had evidence he was a skeptic and if he didn’t he was in
denial.
There are three characteristics of scientific skepticism differentiating it from denial.
1. A skeptic is familiar with the argument in question. In the case of AGW this requires having read
the IPCC reports.
2. A skeptic’s objections are themselves scientific, i.e., they are testable [1].
3. A skeptic is willing to be wrong.
The third distinction follows directly from the second. If one is proposing testable objections then one
has to be willing to be wrong if the objections are falsified. I promised my friend I would review Botkin’s
objections. Here is what Botkin writes on his web site [2]:
“… one can only be rather agnostic about the role that human actions have played and are
playing in climate change. A new, important paper in the journal Science casts some fascinating
light on the question of whether carbon dioxide change precedes temperature change, and
therefore is a likely cause of the temperature change, or whether temperature change precedes
carbon dioxide change, casting doubt on the role of the greenhouse gas in climate change.”
His objection to AGW theory is unusual but testable in two ways. The first Botkin hypothesis is that the
timing of temperature change relative to carbon dioxide can be accurately determined by one sample in
a 240,000 year old ice core and the second is that this lone result would falsify a vast expanse of settled
science. Botkin’s first hypothesis is irrelevant to AGW theory but has been falsified. Botkin would have
to provide extraordinary evidence to support his second hypothesis which he fails to do and which
anyway nearly certainly does not exist. Pointedly, the burden is Botkin’s to provide evidence and he
provides none. Both hypotheses are contradicted anyway by the conclusions in the only journal article
Botkin cites; not a good start for him.
We have known for more than 150 years since John Tindall’s famous experiments that carbon dioxide is
a greenhouse gas [3] and that greenhouse gases have clearly played an important role in determining
the climate during Earth’s history [4].
To cast doubt on the role of greenhouse gases to change the climate, one would have to question
quantum mechanics and Maxwell’s equations as well as discover some other explanation for our
existence and why the Earth isn’t frozen over solid and indeed find an alternate explanation for the
entire paleoclimate history of Earth and Venus, a tall order and why climate skepticism is problematic.
To make his “agnostic” case, Botkin relies on an article published in the journal Science in 2003 by
Nicolas Caillon and colleagues [5]. This paper’s authors attempted to estimate the relative timing
between the Antarctic climate change and the release of carbon dioxide into the atmosphere 240,000
years ago, Termination III shown in the figure. The authors estimate that the temperature rise in the
Antarctic preceded the release of carbon dioxide into the atmosphere by about 800 years. This is the
result Botkin used to cast “doubt on the role of the greenhouse gas in climate change.” Botkin’s first
hypothesis that the timing estimate was accurate is irrelevant to AGW theory but it is interesting that
the Caillon paper itself states: “The following conclusions … must be considered tentative.”
For the record, another paper published in Science in 2009 by Drysdale et al. regards Termination II [6],
corrects the timing of this event, 141,000 years ago, by about 10,000 years.
During the Pleistocene the geological epoch spanning 2,588,000 to 11,700 years ago, the Earth
experienced repeated glaciations some of which are shown in the figure. At the glacial maximums
kilometers of ice covered New York while during the interglacial periods such as Termination III, most of
Canada was ice free. It has been suspected since the work of John Croll in 1875 [7] that these ice age
episodes were caused by variations in Earth’s orbit or Milankovich Cycles. Milutin Milankovic made a
convincing case for this in 1941 [8] and it was confirmed in 1976 [9]. What was remarkable is that this
repeated warming and cooling of the Earth’s climate tracks nearly exactly the rise and fall of
atmospheric carbon dioxide and methane. In a word, the Earth’s carbon cycle represents a very strong
positive feedback mechanism which would amplify any forcing function which might initiate climate
change. Another paper published in the journal Nature in 2012 by Jeremy Shakun et al explains [10] that
while Antarctic warming may have preceded the release of carbon dioxide into the atmosphere; the
warming of the globe came after the release. The orbital redistribution of solar insolation initiated
warming at the poles, which initiated a release of carbon dioxide which then caused the entire planet to
warm.
Caillon’s paper does not contradict that carbon dioxide is a greenhouse gas or question the role of
greenhouse gases in determining the climate of a planet such as Earth. The Caillon paper states:
“The situation at Termination III differs from the recent anthropogenic CO2 increase. As recently
noted by Kump, we should distinguish between internal influences (such as the deglacial CO2
increase) and external influences (such as the anthropogenic CO2 increase) on the climate
system. Although the recent CO2 increase has clearly been imposed first, as a result of
anthropogenic activities, it naturally takes, at Termination III, some time for CO2 to outgas from
the ocean once it starts to react to a climate change that is first felt in the atmosphere. The
sequence of events during this Termination is fully consistent with CO2 participating in the latter
4200 years of the warming”.
On his web site Botkin cites a second paper published after he wrote his book which addresses the
timing uncertainty in the Caillon measurements. The later paper by Parrenin et al. [11] concerns itself
with the most recent termination, the transition between the Last Glacial Maximum 22,000 years ago
and the beginning of the Holocene 11,700 years ago. Since this is very recent, the timing of events is
expected to be much more accurate than those reported by Caillon. Parrenin shows that the carbon
dioxide was released into the atmosphere simultaneous with the warming of the Antarctic. This is as we
expect and is probably also what happened 240,000 years ago. The release of carbon dioxide by a
warming Earth was not just a contributor to the last half of the warming but center stage to the whole
event. Thus Botkin’s hypothesis is falsified.
If Botkin was scientifically skeptical of AGW theory and not simply in denial he would have done the mea
culpa and admitted he had gotten it wrong, no big deal. We all make mistakes. Instead he compounds
his mistake with obfuscating illogic. Why he does this is more a problem for cognitive psychology than
climate physics. But it leaves no doubt that Botkin is in denial. The cognitive psychologist Daniel Kahan
discusses denial in an outstanding lecture he delivered at Cambridge University [12]. Frankly we all tend
to behave this way; it is a Homo sapiens design flaw. :+)
Still I am sympathetic with what I generously think might be Botkin’s concern. The attention focused on
global warming distracts us from all the other human misbehaviors. My own views correspond with
those of the National Academy of Sciences [13].
“…habitat destruction, fragmentation, and over-exploitation, even without climate change, could
result in a mass extinction within the next few centuries equivalent in magnitude to the one that
wiped out the dinosaurs. With the ongoing pressures of climate change, comparable levels of
extinction conceivably could occur before the year 2100”
In 2010 a drought year, the net loss of carbon to the atmosphere from the Amazon was 500,000 tons. In
2011 a wet year the net loss was 50,000 tons [14]. The Amazon is no longer a sink for human emissions.
Human-caused climate change and human-caused deforestation are now coherent and reinforcing.
I cannot recommend Botkin’s book. His denial of AGW is a significant flaw. While there might be parts
of his book that are worthwhile, it is unreliable and unless a reader has access to the original science the
reader cannot separate the good from the bad. If the reader has access to the science then she does
not need to read Botkin. Read Canfield’s “Oxygen” instead.
Figure 1. Antarctic temperature and atmospheric carbon dioxide from Vostok Ice core
http://upload.wikimedia.org/wikipedia/commons/c/c2/Vostok-ice-core-petit.png
[1] Karl Popper, The Logic of Scientific Discovery, originally published in 1935, I have the 2007 Routledge
version.
[2] http://www.danielbbotkin.com/2013/03/04/carbon-dioxide-and-temperature-who-has-led-whom/
[3] John Tyndall, On the absorption and radiation of heat by gases and vapours, and on the physical
connexion of radiation, absorption, and conduction, Philosophical Magazine Series 4, 22, 169-194, 273285.
[4] Raymond Pierrehumbert, Principles of Planetary Climate, Cambridge, 2010.
[5] Caillon, et al, “Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination
Ill.” Science, 2003. 299: 1728–1731
[6] Drysdale et al, Evidence for Obliquity Forcing of Glacial Termination II, Science, Vol 325, 18
September, 2009.
[7] http://en.wikipedia.org/wiki/James_Croll
[8] Milankovitch, Milutin (1998) [1941]. Canon of Insolation and the Ice Age Problem. Belgrade: Zavod za
Udz̆benike i Nastavna Sredstva. ISBN 86-17-06619-9.; see also "Astronomical Theory of Climate Change"
[9] Imbrie and Imbrie, "Ice ages - solving the mystery", Harvard University Press, 1979 and Hays, J. D.;
Imbrie, J.; Shackleton, N. J. (1976). "Variations in the Earth's Orbit: Pacemaker of the Ice Ages". Science 194 (4270):
1121–1132. doi:10.1126/science.194.4270.1121 . PMID 17790893
[10] Jeremy D. Shakun, Peter U. Clark, Feng He, Shaun A. Marcott, Alan C. Mix, Zhengyu Liu, Bette OttoBliesner, Andreas Schmittner & Edouard Bard, Global warming preceded by increasing carbon dioxide
concentrations during the last deglaciation, Nature, Volume: 484, Pages: 49–54, 05 April 2012 DOI:
doi:10.1038/nature10915
[11] Parrenin, et. al., “Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the
Last Deglacial Warming,” Science, 2013. 339: p. 1060
[12] http://www.sms.cam.ac.uk/media/1083337;jsessionid=24318FACA80319A17E5841ADF99EDF23
[13] http://www.nap.edu/catalog.php?record_id=18373
[14] Jennifer Balch, Drought and fire change sink to source, Nature, Vol 506, 6 February, 2014.