How does rising atmospheric CO2 affect marine organisms?

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The Holocene Climate of the Antarctic Peninsula
Yoon, H.I., Park, B.-K., Kim, Y. and Kang, C.Y.  2002.  Glaciomarine sedimentation and its paleoclimatic implications on the Antarctic Peninsula shelf over the last 15,000 years.  Palaeogeography, Palaeoclimatology, Palaeoecology 185: 235-254.

What was done
The authors analyzed data pertaining to several "sedimentological, geochemical and micropalaeontological parameters" extracted from radiocarbon-dated sediment cores that were retrieved from the Antarctic Peninsula's western continental shelf.

What was learned
Deglaciation of the outer shelf commenced prior to 15,000 years before present (BP); but a return to colder conditions occurred between 12,800 and 11,600 years BP, "coincident with the Younger Dryas event in the North Atlantic region."  The inner shelf, however, was not deglaciated until about 11,000 years BP; and this event was ultimately followed by a period of enhanced biological productivity the authors refer to as a climatic optimum, which held sway between 6000 and 2500 years BP and "roughly coincided with its equivalent in the Northern Hemisphere of 7000 to 4000 years BP."

The onset of the Neoglacial at approximately 2500 years BP was characterized by a decrease in total organic carbon and diatom abundance in the seabed sediments, reflecting, in the words of the authors, "the formation of more extensive and seasonally persistent sea ice, as evidenced by an increase in percentage of sea-ice taxa."  This was a time in which "a distinct glacial re-advance took place in the Antarctic Peninsula fjords and shelf, probably caused by a renewed cooling (Shevenell et al., 1996; Leventer et al., 1996)."  Most of the paleoclimatic data also exhibited greater variability both before and after the mid-Holocene climatic optimum.

What it means
These findings have several important implications.  First, the authors say they indicate that "the maritime record on the Antarctic Peninsula shelf suggests close chronological correlation with Holocene glacial events in the Northern Hemisphere, indicating the possibility of coherent climate variability in the Holocene," which observation fortifies our contention that the millennial-scale climate variability so well established in the Northern Hemisphere (of the Little Ice Age / Medieval Warm Period type) is truly global in nature.  Second, the authors' data demonstrate that climate is typically much more stable during warmer times (such as the mid-Holocene climatic optimum or the current Modern Warm Period) than it is during cooler (Neoglacial) or colder (glacial) times, when significant and rapid warmings and coolings often occur, as we have also repeatedly noted.  Third, the data are in complete harmony with the well-established fact that a warmer world is a more productive world.

So what do the results of this study tell us about the state of the world today?  They tell us there is absolutely nothing unusual about it ... except, perhaps, that it's a much more pleasant and productive place than it is when cooler conditions prevail.

Leventer, A., Domack, E.W., Ishman, S.E., Brachfeld, S., McClennen, C.E. and Manly, P.  1996.  Productivity cycles of 200-300 years in the Antarctic Peninsula region: understanding linkages among the sun, atmosphere, oceans, sea ice and biota.  Geological Society of America Bulletin 108: 1626-1644.

Shevenell, A.E., Domack, E.W. and Kernan, G.M.  1996.  Record of Holocene paleoclimate changes along the Antarctic Peninsula: evidence from glacial marine sediments, Lallemand Fjord. In: Banks, M.R. and Brown, M.J. (Eds.), Climate Succession and Glacial History Over the Past Five Million Years.  Royal Society of Tasmania 130: 55-64.

Reviewed 25 December 2002