Vostok Ice Cores and the 8,000-year Lag

[Valin]

Power Line:

John Hinderaker

December 28, 2014

 

During Earth’s recent history, there has been a relationship between carbon dioxide and global temperatures: when temperatures rise, the concentration of CO2 subsequently rises, and when temperatures fall, CO2 concentration thereafter declines. Ice cores from Vostok in Antarctica have been studied intensively to analyze temperatures and concentrations of various gases over the course of millennia. Euan Mearns reviews the literature as it relates to both CO2 and methane:

 

 

In their seminal paper on the Vostok Ice Core, Petit et al (1999) note that CO2 lags temperature during the onset of glaciations by several thousand years but offer no explanation. They also observe that CH4 and CO2 are not perfectly aligned with each other but offer no explanation. The significance of these observations [is] therefore ignored. At the onset of glaciations temperature drops to glacial values before CO2 begins to fall suggesting that CO2 has little influence on temperature modulation at these times. …

 

The fit of CO2 to temperature is actually not nearly so tight as for CH4. There is a persistent tendency for CO2 to lag temperature throughout and this time lag is most pronounced at the onset of each glacial cycle “where CO2 lags temperature by several thousand years.”

(Snip)

 

Rising temperatures cause an increase in CO2 levels primarily because warmer oceans hold less CO2. (“The most likely source for most of the CO2 is considered to be the oceans where warming seawater can hold less CO2.”) At neither end of the glaciation cycle does CO2 concentration forecast temperature. The linked article contains much technical discussion of the mechanisms by which rising and falling temperatures cause (over a time period of millennia) rising and falling levels of CO2. These are the paper’s conclusions:

 

(Snip)

 

 

 

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I recall Christopher Monckton mentioning this years ago. As I recall he used a 700 year figure.