How does rising atmospheric CO2 affect marine organisms?

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The Holocene History of Alaskan Land-Based Glacier Activity
Barclay, D.J., Wiles, G.C. and Calkin, P.E. 2009. Holocene glacier fluctuations in Alaska. Quaternary Science Reviews 28: 2034-2048.

What was done
The authors provide an extensive and up-to-date review of what is known about glacial activity - and its relationship to temperature - throughout Alaska during the Holocene.

What was learned
Barclay et al. report that the "termini of land-based valley glaciers were in retracted positions during the early to middle Holocene," but that "neoglaciation was underway in some areas by 4.5-4.0 ka and major advances of land-based termini occurred by 3.0 ka." Most dramatic of all, however, were the Little Ice Age (LIA) glacial advances, which culminated in two phases in the 1540s-1710s and in the 1810s-1880s, of which they say that "moraines of these middle and late LIA maxima are invariably the Holocene maxima in coastal southern Alaska," adding that "LIA advances are also recognized as major expansions in all glacierized mountain ranges in Alaska." In addition, they state that researchers have determined that "Holocene fluctuations of Alaskan land-terminating glaciers have primarily been forced by multi-decadal and longer timescale changes in temperature."

What it means
These several observations suggest that 20th-century global warming, as experienced in Alaska, likely began from the coldest portion of the current interglacial period, leading us to conclude it's about time that we got a little relief from that much-less-than-desirable period of interglacial record-breaking cold. In addition, we note that the earth descended into that wretched state without any help from declining atmospheric CO2 concentrations, which further suggests there is no need to invoke the assistance of the historical rise in the air's CO2 content as the reason for our emergence from the Little Ice Age. It's all been natural, the cooling and warming alike.

Reviewed 23 December 2009