How does rising atmospheric CO2 affect marine organisms?

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Millennial-Scale Oscillations of a Maritime Plateau Glacier of Western Norway
Bakke, J., Lie, , Nesje, A., Dahl, S.O. and Paasche, .  2005.  Utilizing physical sediment variability in glacier-fed lakes for continuous glacier reconstructions during the Holocene, northern Folgefonna, western Norway.  The Holocene 15: 161-176.

What was done
Physical parameters of glaciolacustrine sediments retrieved from two glacier-fed lakes and a peat bog north of the ice cap of northern Folgefonna, the seventh largest glacier in Norway, were used to derive a long-term history of glacier equilibrium-line altitude (ELA).

What was learned
The authors note that their ELA reconstruction reveals both century- and millennial-scale glacier expansions along with some less extensive decadal-scale fluctuations over the past 2300 years.  Most notable is: (1) the ELA minimum of the first Subatlantic glacial event that preceded the Roman Warm Period (RWP), (2) the dramatic rise of the ELA at the start of the RWP, which peaked between 2000 and 1800 years before present (yr BP), (3) the subsequent steep but jagged ELA decline throughout the Dark Ages Cold Period (DACP) that extended from approximately 1800 to 1200 yr BP, (4) the rapid rise of the ELA at the commencement of the Medieval Warm Period, which prevailed from 1200 to 500 yr BP, (5) the return of the ELA to DACP levels during the Little Ice Age, which prevailed from 500 to 100 yr BP, and (6) the development of the Modern Warm Period over the final century of the record.  Also of interest is the fact that although the current ELA of the glacier is higher than the ELA that prevailed during the Medieval Warm Period, it is lower than the ELA that prevailed during the Roman Warm Period, indicative of the fact that the region's current temperature has not yet risen to the level of warmth that prevailed in that part of the world two millennia ago.

What it means
Independent of whatever the atmosphere's CO2 concentration may be doing, earth's climate oscillates on a millennial time scale that brings recurrent alternating multi-century cold and warm spells to all parts of the planet, as illustrated in this study for a portion of western Norway.

Reviewed 13 July 2005