Carbon Dioxide Variations Have a Key Role in Creating Ice Ages

© 2000 Eugene S. Takle

A longstanding question in paleoclimatology is how the periodic changes in the Earth's orbit aroung the sun, which are known to be related to glacial cycles, actually cause the onset of ice ages. Shackleton (2000) reports new evidence showing that the orbital changes somehow lead to changes in atmospheric CO2 which in turn modifies the greenhouse effect which then regulates the expansion and contraction of ice sheets. He has found that orbital variations themselves cannot directly lead to variations in ice volume, but that intermediate mechanism of sufficient magnitude to control global temperatures and thereby the equatorward advance and poleward retreat of ice sheets. Kerr (200) provides a summary of the Shakleton (2000) paper.


References

Kerr, R.A., 2000: Ice, mud point to CO2 role in glacial cycle. Science, 289, 1868.

Shackleton, N.J., 2000: The 100,000-year ice age cycle identified and found to lag temperature, carbon dioxide, and orbital eccentricity. Science, 289, 1897-1902