How does rising atmospheric CO2 affect marine organisms?

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Millennial Temperature Change in Alaska
Barclay, D.J., Wiles, G.C. and Calkin, P.E.  1999.  A 1119-year tree-ring-width chronology from western Prince William Sound, southern Alaska.  The Holocene 9: 79-84.

What was done
Using tree-ring-width data, the authors constructed a 1119-year proxy temperature record for southern Alaska covering the time period from A.D. 873 to 1991.

What was learned
The tree ring record indicated there were a number of intervals with both cooler and warmer temperatures than present: cooler intervals were centered on A.D. 1400, 1660 and 1870, warm intervals at A.D. 1300, 1440 and 1820.  When comparing their proxy temperature record with three major intervals of glacial expansion, the authors noted that, although glacial advances generally coincide with multidecadal periods of cooler temperatures, in two of these instances they overlap with multidecadal warm intervals.

What it means
This study demonstrates the complexity of the phenomena that promote glacial growth and retreat.  It also demonstrates the naturally fluctuating nature of climate - how the climate of this one region has been both warmer and colder than it is presently over a period of time (the first 1,000 years of the record) when the air's CO2 concentration fluctuated but little.

Reviewed 15 May 1999