How does rising atmospheric CO2 affect marine organisms?

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Six Thousand Heat Flow Measurements Can't Be Wrong
Huang, S. and Pollack, H.N. 1997. Late Quaternary temperature changes seen in world-wide continental heat flow measurements. Geophysical Research Letters 24: 1947-1950.

What was done
The authors searched the large database of terrestrial heat flow measurements compiled by the International Heat Flow Commission of the International Association of Seismology and Physics of the Earth's Interior for measurements suitable for reconstructing an average ground surface temperature history of the earth over the last 20,000 years. Based on a total of 6,144 qualifying sets of heat flow measurements obtained from every continent of the globe, they produced a global climate reconstruction, which, they state, is "independent of other proxy interpretations [and] of any preconceptions or biases as to the nature of the actual climate history."

What was learned
From their reconstruction of "a global climate history from worldwide observations," the authors found strong evidence that the Medieval Warm Period was indeed warmer than it is now, by perhaps as much as 0.5C, which is only 0.1C less than the peak warmth of the mid-Holocene Maximum. Their data also suggested that the Little Ice Age was as much as 0.7C cooler than it is currently.

What it means
Contrary to the recent claim of some that the Medieval Warm Period and Little Ice Age were neither real nor global climatic phenomena, this study tells a very different story, which, because of the massive data base upon which it rests, must be the correct one.

Reviewed 13 September 2000