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State of Sophistry
Tony Noerpel
There is a particularly sophistic science-denial argument which has been around since 2004. This popular
argument cites a paper published in the journal Science in 2003 by Nicolas Caillon and colleagues [1] and
then badly misinterprets it. It seems unlikely that whoever originated the argument read or understood
the paper and it seems equally unlikely that they expected anyone else to read the paper either because
the Caillon paper contradicts the argument. The reason this is relevant to us still is that denier and
forest ecologist Daniel Botkin used this argument earlier this year in testimony to congress [2]. If we
first discuss the actual science and then examine the Botkin canard in that light, we can better
appreciate its irrationality.
Caillon and colleagues estimated that the temperature rise in the Antarctic preceded the release of
carbon dioxide into the atmosphere by about 800 years during Termination III (Figure 1), 240,000 years
ago. 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”.
During the Pleistocene the geological epoch spanning 2,588,000 to 11,700 years ago, the Earth
experienced repeated glaciations as shown in Figure 1. At glacial maximums kilometers of ice covered
New York (Figure 2) while during the interglacial periods, most of Canada was ice free. It has been
suspected since 1875 [3] that these ice age episodes were caused by variations in Earth’s orbit. Milutin
Milankovic made a convincing case for this in 1941 [4] which was confirmed in 1976 [5]. Remarkably
this repeated warming and cooling of the Earth’s climate tracks nearly exactly the rise and fall of
atmospheric carbon dioxide (Figure 1) and methane.
When the Earth surface warms for any reason, carbon is released from surface reservoirs such as the
oceans and soils into the atmosphere and when the Earth surface cools carbon is absorbed from the
atmosphere by these reservoirs. This exchange of carbon enhances or amplifies the initial forcing. This
is an important result of the Caillon paper and the paleoclimate literature which Botkin missed. While
there are many positive and negative carbon feedbacks in nature the aggregate are clearly amplifying
over millennial time scale as evident by Figure 1. The important point is not the 800 year lag between
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warming of the Antarctic and the release of carbon into the atmosphere but that carbon should be
released at all. Our emissions are making things bad and Mother Nature is going to make them worse.
Reading over blog entries about this argument, I’ve found that many deniers, perhaps understandably,
are confused by positive feedback. They think this would cause the Earth to experience a runaway
greenhouse and since that has never happened positive feedbacks cannot exist. However so long as the
feedback factor is less than 1, the positive feedback will simply stabilize at a higher temperature. And
for a practical system like Earth, there are limits which eventually attenuate even strong positive
feedbacks. Of course a hot house climate such as that during the Cretaceous or the Eocene is possible
and that would be much hotter than anything Homo Sapiens have ever experienced.
A careful examination of the most recent glacial termination which took place between 22,000 years ago
and 11,700 years ago, in Figure 3 [6] illustrates this explicitly. The initiating forcing was the ramping up
during the summer months of solar insolation in the Northern Hemisphere; this is the blue curve labeled
“NH summer insolation”. The term insolation refers to the strength of solar radiation at a specific
location and time; in this case latitude 65o North on June 21. This increased flux of solar energy was due
to Earth’s periodic orbital variations causing glaciers covering the Northern Hemisphere to melt.
Glaciers expand when accumulated winter snow exceeds summer melt and contract when summer melt
exceeds winter snow accumulation. Thus a small local perturbation in solar insolation was enough to tip
the balance into ice sheet retreat. The denier argument that “climate is always changing” is actually a
warning. The climate changes quite a lot with very small and even localized changes in energy flux.
Since the melting ice sheets exposed darker earth and water, less of the sun’s incident radiation was
reflected back out into space. This phenomenon is called albedo feedback. This too is positive. The
fresh water flooding the North Atlantic from the melting ice sheet caused the Atlantic Ocean Meridional
Overturning Circulation (AMOC) to slow down stopping the flow of heat from the south to the north
causing in turn Antarctica to warm up, i.e., “a seesawing of heat between the hemispheres.” This is
shown by the thick brown curve in Figure 3 as well as by the red curve in Figure 4 [7]. The release of
carbon into the atmosphere begins soon after the warming in the Antarctic, shown by the red dots in
Figure 3 and the yellow dots in Figure 4. The blue curve in Figure 4 is the global proxy temperature
record. Thus the most important observation is that Global temperature change follows the release of
carbon dioxide into the atmosphere.
Interestingly the surface temperature measured in the Greenland ice core did not rise until several
thousand years later about 14,700 years ago at the beginning of the Bolling-Allerod. The rise in carbon
dioxide was 75 ppmV over 6000 years or 1.25 ppm per century. Current human emissions are increasing
the atmospheric carbon dioxide level by 2.25 ppm per year. The second important observation is that
human emissions are increasing atmospheric carbon dioxide more than 100 times faster than one of
the more dramatic natural events.
What fools Botkin and other deniers, besides a neo-liberal economic ideology, is the original estimated
800 year lag between warming signature in the Antarctic ice core and the accumulation of atmospheric
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carbon dioxide. Deniers argue that since warming preceded carbon accumulation this one time then it
must be true even today exonerating human emissions of fossil fuels. But carbon dioxide was never
implicated in the initiation of glacial retreat. There were likely errors in the 800 year lag estimate which
those authors admitted. The Antarctic warming does not in any event represent global warming. And
finally that one cannot extrapolate from one paleoclimate event to the current anthropogenic event.
Exactly as Caillon et al. state in the very paper deniers referenced one cannot confuse the exchange of
carbon between various surface reservoirs and the atmosphere which happens all the time with the
release of fossil carbon which had been isolated from the surface for hundreds of millions of years.
You can listen to Botkin present this argument to Congress [2] or read it on his web site [8].
“… 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.”
Botkin is here referring to a Science paper by Parrenin et al [9]. Using better timing estimates, these
authors reduce the lag between the warming of the Antarctic and the release of carbon dioxide from the
original 800 year estimate [1] to near simultaneity (see Figure 5). In other words, the entire stupid
argument was blown away because there is no 800 year lag. Curiously, Botkin did not mention the
Parrenin paper to Congress. Botkin’s argument is simply irrational.
[1] Caillon, et al, “Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination
Ill.” Science, 2003. 299: 1728–1731
[2] http://science.house.gov/hearing/full-committee-hearing-examining-un-intergovernmental-panelclimate-change-process
[3] http://en.wikipedia.org/wiki/James_Croll
[4] 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"
[5] 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
[6] Christo Buizert et al., Greenland temperature response to climate forcing during the last
deglaciation, Science 345, 1177 (2014); DOI: 10.1126/science.1254961
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[7] 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
[8] http://www.danielbbotkin.com/2013/03/04/carbon-dioxide-and-temperature-who-has-led-whom/
[9] Parrenin, et. al., “Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the
Last Deglacial Warming,” Science, 2013. 339: p. 1060
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
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Figure 2
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Figure 3
Figure 4
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Figure 5