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The 800 year lag in CO2 after temperature – graphed

Carbon dioxide follows temperature in the Vostok Ice Cores

In the 1990’s the classic Vostok ice core graph showed temperature and carbon in lock step moving at the same time. It made sense to worry that carbon dioxide did influence temperature. But by 2003 new data came in and it was clear that carbon lagged behind temperature. The link was back to front. Temperatures appear to control carbon, and while it’s possible that carbon also influences temperature these ice cores don’t show much evidence of that. After temperatures rise, on average it takes 800 years before carbon starts to move. The extraordinary thing is that the lag is well accepted by climatologists, yet virtually unknown outside these circles. The fact that temperature leads is not controversial. It’s relevance is debated.

It’s impossible to see a lag of centuries on a graph that covers half a million years so I have regraphed the data from the original sources, CO2 Data here and Temperature data here (Petit 1999), and scaled the graphs out so that the lag is visible to the naked eye. What follows is the complete set from 420,000 years to 5,000 years before the present.

The bottom line is that rising temperatures cause carbon levels to rise. Carbon may still influence temperatures, but these ice cores are neutral on that. If both factors caused each other to rise significantly, positive feedback would become exponential. We’d see a runaway greenhouse effect. It hasn’t happened. Some other factor is more important than carbon dioxide, or carbon’s role is minor.

Permission for use: These images are available for media and non-profit use. As a courtesy please email me “joanne AT joannenova.com.au” (replace the ‘AT’ with ‘@’). Thank you. There are also larger files available in tif format for printing. Click on the link to the right hand side of each graph.

Note: The temperatures here are measured in relation to the present temperature. In other words, most of the time for the last million years it’s been much colder.

MORE INFO

Other posts on Vostok Ice Cores.

REFERENCES

Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image
Click here for a larger TIFF imageor.. JPG image


Update: Aug 18 2013 adding page links.

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Last Update: Oct 18 2020: The original data was stored at CDIAC: here  http://cdiac.ornl.gov/ftp/trends/temp/vostok/vostok.1999.temp.dat  and http://cdiac.ornl.gov/ftp/trends/co2/vostok.icecore.co2. But both these links are now defunct.

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