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Is there a time-lagged correlation with CO2 levels preceding temperature? Does the time lag change from time to time?

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2 Answers 2

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From wikipedia:

  • Studies of the Vostok ice core show that at the "beginning of the deglaciations, the CO$_2$ increase either was in phase or lagged by less than ~1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciations".$^{[1]}$ Recent warming is followed by carbon dioxide levels with only a 5 months delay.$^{[2]}$ The time lag has been used to argue that the current rise in CO$_2$ is a result of warming and not a cause. While it is generally agreed that variations before the industrial age are mostly timed by astronomical forcing,$^{[3]}$ a main part of current warming is found to be timed by anthropogenic releases of CO$_2$, having a much closer time relation not observed in the past (thus returning the argument to the importance of human CO$_2$ emissions). Analysis of carbon isotopes in atmospheric CO$_2$ shows that the recent observed CO$_2$ increase cannot have come from the oceans, volcanoes, or the biosphere, and thus is not a response to rising temperatures as would be required if the same processes creating past lags were active now.$^{[4]}$
  1. Historical carbon dioxide record from the Vostok ice core - Carbon Dioxide Information Analysis Center, 2003.

  2. Spencer R. Weart, 2006, The Discovery of Global Warming

  3. Kuo et. al., 1990, Coherence established between atmospheric carbon dioxide and global temperature

  4. More Notes on Global Warming - Physics Today, 2005

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Studies of the Vostok ice core show that at the "beginning of the deglaciations, the CO2 increase either was in phase or lagged by less than ~1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciations".[1] Recent warming is followed by carbon dioxide levels with only a 5 months delay.

No, the Vostok data showed the CO2 was always in "phase" and always "lagged" the temperature, meaning it was a RESPONSE to, not a CAUSE of earths temperature. CO2 is a result of, not cause of global temperature. Period.

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    $\begingroup$ The final statement is wrong. Period. CO2 and temperature interact in a positive feedback loop, i.e. increasing either one causes an increase in the other. In glacial cycles the changes were initiated by orbital effects, which caused higher temperatures, which caused higher CO2, ... Current climate changes are initiated by increased CO2, which causes higher temperature, which causes higher CO2, ... $\endgroup$
    – Mark
    Apr 7 at 15:05

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