1/31/09 Update:
Click here for a related analysis of temperature driving CO2.
3/8/16 Update: Fixed a broken link.
Q) Has atmospheric CO2 historically (over the last 650,000 years) driven temperature?
A) No! Over that time frame, temperature has primarily driven atmospheric CO2 (and
Milankovitch cycles have primarily driven temperature). As temperatures rise,
CO2 is released from the oceans. As temperatures decline, CO2 is reabsorbed into the oceans.
Note: In this post, I will present 4 independent examples of peer reviewed science published in peer reviewed science journals which demonstrate the above conclusion. These studies were published in 1999, 2001, 2003 and 2005. If there exists
any peer reviewed study which has
ever found otherwise, I am unaware of it.
Q) Does this mean Man Made CO2 does not warm the planet?
A) No. Man Made CO2 does warm the planet, but not enough to matter (ever). In fact, a peer reviewed study published in November of 2007 concludes that continuing on our present course is unlikely to raise temperatures by much more than 0.4C over the next 100 years:
Here is the peer reviewed science which proves the above conclusion.
Here is the published version of the above peer reviewed science.
Here is a slightly more lay person friendly discussion (from a PhD Physicist) of the above peer reviewed science.
(Included is the analysis of why we could expect about 0.4C of man made warming in the next 100 years.)
Here is just a sampling of how the scientific community has reacted to this
very recent peer reviewed paper (and others).
The core argument in asserting CO2 driven Climate Change is the fact that, for hundreds of thousands of years, there has been a close correlation between temperature and atmospheric CO2. This correlation is, quite accurately, presented in charts like this one from The Sierra Club:
Click here to view the image on the Sierra Club server.
The implication is that CO2 has historically driven temperature and that any elevation of CO2 above relatively recent historic norms will result in a corresponding increase in temperatures above historic norms.
But:
1) Over the last 600 million years, it is only in the relatively recent past that we’ve seen
any consistent correlation between temperature and CO2:
Click the image to enlarge it:
Click here to learn more about this chart.
A) Sources for the above chart:
i)
The Paleomap Project by Dr. C.R. Scotese, a
PhD geologist at the University of Texas at Arlington.
ii)
R.A. Berner, 2001 (GEOCARB III), as published in the American Journal of Science,
Vol. 301, February 2001, P.182-204.
B) Note, in the above chart, that we are presently in one of the three
coldest periods ever seen in the last 600 million years. In fact, quoting
this source:
"During most of the last 1 billion years the earth had no permanent ice [as it cycled (NATURALLY) in and out of multi-million year Ice Ages]"
Another Note: When I followed the instructions contained in
Geocarb III for translating RCO2 into ppm, the chart which I created (using
the Geocarb III data file downloaded from
this NOAA page) showed the exact same pattern as the above chart, but it showed even
higher levels of historic CO2 ppm than that chart:
Click the image to enlarge it:
2) About 500 to 600 million years ago, CO2 was, due to volcanic activity, about 20 times higher than today (using
the Geocarb III data file,
my chart and a
current CO2 level of 385 ppm). That conclusion is very consistent with
this additional chart. If “runaway global warming” was ever going to happen, it would have happened then. It did not. To the contrary, about 460 million years ago, when CO2 levels were about 10-15 times higher than today, the planet fell into one of the three coldest periods in the last 600 million years (much like the present period).
3) At
about 386ppm CO2, we are already about 29% above
relatively recent historic highs for CO2.
4) And yet, we are not yet as warm as
any of the previous
four perfectly normal, perfectly natural interglacial warming periods:
Click the image to enlarge it.
Click here to further put current temperatures in perspective
(and, more readily verify the source data used in the chart).
Note: The current interglacial warming period is, in
no way, unprecedented. According to NASA, there have been:
“around 100 [glacial/interglacial cycles] in the last 2.5 million years”
5) In fact, as the following NOAA chart clearly demonstrates, temperatures were more than 2C higher as recently as 8-10 thousand years ago (at what may well turn out to have been the apex, or climatic optimum, for the current interglacial warming period):
Again, click the above image to view the NOAA source image. Aside from being mirror images of one another, the above NOAA chart is perfectly consistent with
my own chart of
the very same data (dating back to 140,000 years ago).
So, how do we reconcile these observations with the historic data? All we need to do is take a closer look at the historic data (and find that, over the last 650,000 years, temperature has driven CO2, and
not the other way around)!
We can then more easily understand why the previously mentioned peer reviewed study examining “Climate Sensitivity” determined that continuing on our present course is
unlikely to raise temperatures by much more than 0.4C over the next 100 years.
Every peer reviewed ice core study I've ever seen shows that, over the last 650,000 years, CO2 has risen in response to rising temperatures and CO2 has decreased in response to decreasing temperatures.
Quoting from Fischer, H., M. Whalen, J. Smith, D. Mastroianni, and B. Deck, 1999: Ice core records of atmospheric CO2 around the last three glacial terminations. Science, 283, 1712-1714:
"carbon dioxide concentrations increased by 80 to 100 parts per million by volume 600 ± 400 years after the warming of the last three deglaciations."
In other words:
Warming occurred first and,
in response, atmospheric CO2 rose 2 to 10 centuries
later.
"Despite strongly decreasing temperatures, high carbon dioxide concentrations can be sustained for thousands of years during glaciations"
In other words:
High CO2 concentrations "can be sustained for thousands of years" while at the very same time we see "strongly decreasing temperatures" leading us into AND thousands of years
through a glacial period (aka Ice Age).
This study was credible enough for the IPCC to cite it in their 2001 Third Assessment Report (even if they completely ignored one side of the findings and applied their own CO2-centric political spin to the other side of the findings):
“lags of up to 2,000 to 4,000 years in the drawdown of CO2 at the start of glacial periods suggests that the low CO2 concentrations during glacial periods amplify the climate change but do not initiate glaciations (Lorius and Oeschger, 1994; Fischer et al., 1999).”
The "References" page of the above report clearly refers to the same study I've linked to:
“Fischer, H., M. Whalen, J. Smith, D. Mastroianni, and B. Deck, 1999: Ice core records of atmospheric CO2 around the last three glacial terminations. Science, 283, 1712-1714.”
The following are quotes from
a November, 2005 peer reviewed study. Each quote links to the associated peer reviewed study. In total, we have here four independent studies demonstrating that, historically, temperature has driven CO2, not the other way around:
“Fischer et al. (5) concluded that CO2 concentrations lagged Antarctic warmings by 600 ± 400 years during the past three transitions.”
“Monnin et al. (9) found a lag of 800 ± 600 years for termination I”
“Caillon et al. (32), with use of the isotopic composition of argon in air bubbles instead of deuterium, calculated a value of 800 ± 200 years for termination III.”
Additionally,
Siegenthaler, et al. report observed lags of:
"800, 1600, and 2800 years"
and go on to report:
"the best correlation for a lag of CO2 of 1900 years".
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