Jack Hollis wrote:
> On 8 Feb 2007 15:36:39 -0800, "[email protected]"
> <[email protected]> wrote:
>
>>as an aside the CO2 record correlates well with the temperature
>>record, at least over the last few glacial cycles, but there are
>>certain events (typically fast and "dynamical") which did result in
>>dramatic temperature shifts without a CO2 change.
>
>
> Actually, the opposite is true. The data shows that CO2 increases
> only occur after global warming has occurred. It's hard to say that
> CO2 caused global warming in the past when the increase in CO2
> happened after the warming period was already centuries old.
>
> Thus the CO2 seems to have an amplifying effect (of undetermined
> amount) rather than a causal effect. The strongest correlations occur
> for CO2 and temperature with a lag of 1900 years.
>
This is a perfect example of what I am talking about where you get sucked
in by the contrarians, who sound convincing to you because they are telling
you what you want to hear and it goes with your desire to be
individualistic.
Here's just a very small sampling of the peer-reviewed skinny on paleo CO2
and climate:
Nature. 2001 Aug 2;412(6846):523-7.
Covariation of carbon dioxide and temperature from the Vostok ice core
after deuterium-excess correction.
Cuffey KM, Vimeux F.
Department of Geography, and Department of Earth and Planetary Science,
507 McCone Hall, University of California, Berkeley, California 94720-4740,
USA.
[email protected]
Ice-core measurements of carbon dioxide and the deuterium
palaeothermometer reveal significant covariation of temperature and
atmospheric CO2 concentrations throughout the climate cycles of the past
ice ages. This covariation provides compelling evidence that CO2 is an
important forcing factor for climate. But this interpretation is challenged
by some substantial mismatches of the CO2 and deuterium records, especially
during the onset of the last glaciation, about 120 kyr ago. Here we
incorporate measurements of deuterium excess from Vostok in the temperature
reconstruction and show that much of the mismatch is an artefact caused by
variations of climate in the water vapour source regions. Using a model
that corrects for this effect, we derive a new estimate for the covariation
of CO2 and temperature, of r2 = 0.89 for the past 150 kyr and r2 = 0.84 for
the period 350-150 kyr ago. Given the complexity of the biogeochemical
systems involved, this close relationship strongly supports the importance
of carbon dioxide as a forcing factor of climate. Our results also suggest
that the mechanisms responsible for the drawdown of CO2 may be more
responsive to temperature than previously thought.
And this one put a big nail in the coffin of the idea that CO2 and paleo
climate weren't tightly coupled ....
CO2 as a primary driver of Phanerozoic climate
Geological Society of America, Volume 14, Issue 3 (March 2004), pp 4-10
Dana L. Royer1, Robert A. Berner2, Isabel P. Montañez3, Neil J. Tabor4,
David J. Beerling5
1. Department of Geosciences and Institutes of the Environment,
Pennsylvania State University, University Park, Pennsylvania 16802, USA, E-
mail:
[email protected], 2. Department of Geology and Geophysics, Yale
University, New Haven, Connecticut 06520, USA, 3. Department of Geology,
University of California, Davis, California 95616, USA, 4. Department of
Geological Sciences, Southern Methodist University, Dallas, Texas 75275,
USA, 5. Department of Animal and Plant Sciences, University of Sheffield,
Sheffield S10 2TN, UK
Recent studies have purported to show a closer correspondence between
reconstructed Phanerozoic records of cosmic ray flux and temperature than
between CO2 and temperature. The role of the greenhouse gas CO2 in
controlling global temperatures has therefore been questioned. Here we
review the geologic records of CO2 and glaciations and find that CO2 was
low (<500 ppm) during periods of long-lived and widespread continental
glaciations and high (>1000 ppm) during other, warmer periods. The CO2
record is likely robust because independent proxy records are highly
correlated with CO2 predictions from geochemical models. The Phanerozoic
sea surface temperature record as inferred from shallow marine carbonate
delta18O values has been used to quantitatively test the importance of
potential climate forcings, but it fails several first-order tests relative
to more well-established paleoclimatic indicators: both the early Paleozoic
and Mesozoic are calculated to have been too cold for too long. We explore
the possible influence of seawater pH on the delta18O record and find that
a pH-corrected record matches the glacial record much better. Periodic
fluctuations in the cosmic ray flux may be of some climatic significance,
but are likely of second-order importance on a multimillion-year timescale.