How does rising atmospheric CO2 affect marine organisms?

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Tidal Cycles as Agents of Millennial-Scale Climate Change
Keeling, C.D. and Whorf, T.P.  2000.  The 1,800-year oceanic tidal cycle: A possible cause of rapid climate change.  Proceedings of the National Academy of Sciences, USA 97: 3814-3819.

What was done
The authors developed the hypothesis that abrupt millennial-scale climate changes are produced in part by periodic variations in the strength of the global oceanic tide-raising forces caused by resonances in the periodic motions of the earth and moon.  Such variations, according to the authors, cause "periodic cooling of surface ocean water by modulating the intensity of vertical mixing that brings to the surface colder water from below."

What was learned
The authors compared calculated tidal cycles with proxy climate records over the past 34,000 years and found their hypothesis to be supported, as cooler periods of climate were found to correspond with periods of greatest tidal forces.  Of particular interest is the fact that the most recent maximum of the prominent 1,800-year tidal cycle coincided with the cold temperatures of the Little Ice Age in the 16th through 19th centuries.

What it means
If the tidal cycle hypothesis is correct, temperatures will continue to warm for several more centuries, greatly compromising our ability to determine whether or not increasing atmospheric CO2 concentrations cause the globe to warm.  Hence, it was clearly premature for the IPCC to have concluded in 1995 that the balance of evidence suggests a discernable human influence on climate.  Likewise, it is premature for the draft of their new report to parrot the same conclusion.

Reviewed 15 May 2000