How does rising atmospheric CO2 affect marine organisms?

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Climatic Conditions in the Fjord Area of Southern Chile
Rebolledo, L., Sepulveda, J., Lange, C.B., Pantoja, S., Bertrand, S., Hughen, K. and Figueroa, D. 2008. Late Holocene marine productivity changes in Northern Patagonia-Chile inferred from a multi-proxy analysis of Jacaf channel sediments. Estuarine, Coastal and Shelf Science 80: 314-322.

What was done
The authors analyzed changes in marine productivity and contemporaneous terrestrial input in a study of sediment cores retrieved from the Jacaf Channel (44S, 72W) of Chilean Northern Patagonia that contain data pertaining to the past 1800 years, using biogenic opal, siliceous microorganisms, alkenones, and organic (Corg content, molar C/N) and inorganic (Cinorg, Fe, Ti, Ca) elements as proxies for terrestrial input and/or carbonate productivity, after which they compared their findings with those of other researchers who had conducted similar paleoclimatic studies in various parts of South America and Antarctica.

What was learned
Rebolledo et al. report that "the downcore record clearly shows two productivity/climate modes." As they describe it, the first period -- prior to 900 cal yr BP and including the Medieval Warm Period (MWP) -- is characterized by "decreased marine productivity and a reduced continental signal, pointing to diminished precipitation and runoff," while they report that the second period -- between 750 cal yr BP and the late 1800s, and including the Little Ice Age (LIA) -- is characterized by "elevated productivity and an increased continental signal, suggesting higher precipitation and runoff." In addition, their data clearly show that the MWP and LIA "are separated by a relatively abrupt transition of ~150 years."

What it means
In addition to providing another demonstration of the reality of the MWP and LIA in earth's Southern Hemisphere -- where climate alarmists like to pretend they never occurred -- the Chilean, German and U.S. scientists state that the good correspondence between their record and "other paleoclimate studies carried out in South America and Antarctica demonstrates that the Chilean fjord area of Northern Patagonia is not just sensitive to local climatic variability but also to regional and possibly global variability [our italics]."

Reviewed 18 March 2009