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Fig 4. Except for the well known fact that temperature changes precede CO2 changes, the supposed CO2-driven raise of temperatures works ok before temperature reaches max peak. No, the real problems for the CO2-rescue hypothesis appears when temperature drops again. During almost the entire temperature fall, CO2 only drops slightly. In fact, CO2 stays in the area of maximum CO2 warming effect. So we have temperatures falling all the way down even though CO2 concentrations in these concentrations where supposed to be a very strong upwards driver of temperature.  (graph & caption from Frank Lansner, )

Thanks to http://icecap.us/index.php/go/in-the-news/P8/ for the lead to this paper.

Realclimate.org/index.php?p=13:

This is an issue that is often misunderstood in the public sphere and media, so it is worth spending some time to explain it and clarify it. At least three careful ice core studies have shown that CO2 starts to rise about 800 years (600_1000 years) after Antarctic temperature during glacial terminations. These terminations are pronounced warming periods that mark the ends of the ice ages that happen every 100,000 years or so.

Does this prove that CO2 doesn't cause global warming? The answer is no.

The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.  (bold added)

(Did you  notice the twisted logic to try to pin the blame on CO2? After admitting CO2 did not start the warming at the end of ice ages, they say CO2 “could” have caused it to continue! Of course the cause of the original warming could simply have continued.)

Some points:

1. They admit that CO2 did not cause warming:  CO2 starts to rise about 800 years (600_1000 years) after Antarctic temperature

2. The only other relevant statement is: The other 4200 years of warming could in fact have been caused by CO2

Notice the qualifier “could have ... been”? That means they can’t prove it, and are just speculating. Another possibility is that continued warming was caused by whatever started the initial warming simply continuing. Which is most rational?

Here is what the web site created to support the “hockey stick” said

CO2 & Climate

Ice cores refer a core (like an apple core) that usually extends from the surface to thousands of feet down in ice, either in a glacier or polar ice cap. By analyzing the CO2 content and an isotope of Oxygen, scientists deduce the temperature and the CO2 levels at various depths which were deposited over the ages.

When it was found that CO2 and temperature changed together over history, some jumped to the conclusion that CO2 changes caused temperature changes.

However, as better methods of analysis were developed, it became apparent that the temperature changed first and only after an average of 800 years did CO2 change. Since a cause cannot occur before the effect, this proves that CO2 did not cause the temperature changes.

Next it was claimed that “someting unknown” inititated the temperature increase, then CO2 caused it to continue. The problem here is that, at the peak, the temperature reverses, while the CO2 remains high. The below graph shows this situation. Read the whole paper here.

Peer-Reviewed Papers Show CO2 Lags Temperature Changes

(Thanks to Andrew at  Z4, an excellent resource.)

Atmospheric CO2 Concentrations over the Last Glacial Termination

(Science, Vol. 291. no. 5501, 5 January 2001)

- Eric Monnin, Andreas Indermühle, André Dällenbach, Jacqueline Flückiger, Bernhard Stauffer, Thomas F. Stocker, Dominique Raynaud, Jean-Marc Barnola

Ice core records of atmospheric CO2 around the last three glacial terminations

(Science, Vol. 283. no. 5408, pp. 1712 - 1714, 12 March 1999)

- Hubertus Fischer, Martin Wahlen, Jesse Smith, Derek Mastroianni, Bruce Deck

QUOTE: High-resolution records from Antarctic ice cores show that carbon dioxide concentrations increased by 80 to 100 parts per million by volume 600 ± 400 years after the warming of the last three deglaciations.

Southern Hemisphere and Deep-Sea Warming Led Deglacial Atmospheric CO2 Rise and Tropical Warming

(Science, September 27, 2007)

- Lowell Stott, Axel Timmermann, Robert Thunell

QUOTE: Deep sea temperatures warmed by ~2C between 19 and 17 ka B.P. (thousand years before present), leading the rise in atmospheric CO2 and tropical surface ocean warming by ~1000 years.

The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka

(Quaternary Science Reviews, Volume 20, Issue 4, Pages 583-589, February 2001)

- Manfred Mudelsee

QUOTE: Over the full 420 ka of the Vostok record, CO2 variations lag behind atmospheric temperature changes in the Southern Hemisphere by 1.3±1.0 ka

Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination III

(Science 14, Vol. 299. no. 5613, March 2003)

- Nicolas Caillon, Jeffrey P. Severinghaus, Jean Jouzel, Jean-Marc Barnola, Jiancheng Kang, Volodya Y. Lipenkov

QUOTE:  The sequence of events during Termination III suggests that the CO2 increase lagged Antarctic deglacial warming by 800 ± 200 years and preceded the Northern Hemisphere deglaciation.

Here is a full set of the graphs with links to the actual data