Source: data from the Vostok ice core, according to Petit,
Fisher and many more
delta Ts (corr) is the corrected temperature, according to Jouzel
ea.
Zero temperature is current average global temperature.
d18Oatm (measured in N2O) is inversely correlated with
ice sheet formation (here already inverted, to show ice sheet growth
and decline).
The garph is interesting, as it indicates that temperature and methane
(CH4) levels were already near minimum and ice sheets
were near maximum,
at around 113 kyr BP, before CO2 levels starts to
decline. This points to a low influence of CO2 on
temperature.
On longer term, one can see that methane levels more closely follow ice
sheet and temperature fluctuations, while CO2 has more
lags.
methane, d18O (ice sheet growth) and CO2 are measured in
the gas phase, while dD is measured in ice. There may be an error in
the timing
between ice age and gas bubble age of the ice core, but the ice sheet
growth measured by d18O in the bubbles also shows a large lag of CO2.
On the net: 16 December, 2005.
Last change: 6 August, 2007.
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