Once again, another proxy of temperature, planktonic foraminiferal magnesium/calcium ratios, shows global warming over the past 1.35 million years as much or more than today. Recent warming per this proxy begins before the 19th century's increased CO2, and then essentially leveled off and shows no correlation with CO2 levels in the distant past or present.
Science 11 November 2005: Vol. 310. no. 5750, pp. 1009 - 1012 |
The Mid-Pleistocene Transition in the Tropical Pacific
A sea surface temperature (SST) record based on planktonic foraminiferal magnesium/calcium ratios from a site in the western equatorial Pacific warm pool reveals that glacial-interglacial oscillations in SST shifted from a period of 41,000 to 100,000 years at the mid-Pleistocene transition, 950,000 years before the present. SST changes at both periodicities were synchronous with eastern Pacific cold-tongue SSTs but preceded changes in continental ice volume. The timing and nature of tropical Pacific SST changes over the mid-Pleistocene transition implicate a shift in the periodicity of radiative forcing by atmospheric carbon dioxide as the cause of the switch in climate periodicities at this time.
1 Department of Earth Science, University of California Santa Barbara, Santa Barbara, CA 93106–9630, USA.
2 Interdepartmental Program in Marine Science, University of California Santa Barbara, Santa Barbara, CA 93106–9630, USA.
3 Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106–9630, USA.
3 Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106–9630, USA.
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