wnjj wrote:
RambleOnNW wrote:
I have to laugh when I read some of the typical naive postings. Fact is the CO2 level is at 400 ppm and that has not occurred for at least 800,000 years; some scientific sources say 2-15 million years.
The simple fact that the temperature hasn't gone up they way the CO2 level has seems to imply that they don't correlate too well. It makes a nice scare story, though.
Not only that but when I looked at the actual data, higher CO2 levels were lagging (i.e. caused by) temperature increases, not the other way around.
Nice try, but how do you explain how the higher CO2 levels are leading the temperature increases this time around?
The answer is that the previous temperature changes were driven by Interglacials that come along approximately every 100,000 years. This is called the Milankovitch cycle, brought on by changes in the Earth's orbit. Note also that the CO2 levels never exceeded 300 ppm.
This time the temperature changes are not driven by the Milankovitch cycle, but by CO2 emissions.
To claim that the CO2 lag disproves the warming effect of CO2 displays a lack of understanding of the processes that drive Milankovitch cycles. A review of the peer reviewed research into past periods of deglaciation tells us several things:
Deglaciation is not initiated by CO2 but by orbital cycles
CO2 amplifies the warming which cannot be explained by orbital cycles alone
CO2 spreads warming throughout the planet