How does rising atmospheric CO2 affect marine organisms?

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A 2000-Year SST History of the Northeastern Arabian Sea

Paper Reviewed
Munz, P.M., Siccha, M., Luckge, A., Boll, A., Kucera, M. and Schulz, H. 2015. Decadal-resolution record of winter monsoon intensity over the last two millennia from planktic foraminiferal assemblages in the northeastern Arabian Sea. The Holocene 25: 1756-1771.

Working with a pair of sediment cores obtained from the continental margin of the northeastern Arabian Sea just off the coast of Pakistan, Munz et al. (2015) identified the planktic foraminifera remains found at different depths within the cores, which allowed them to develop a continuous record of sea surface temperature (SST) there over the past 2000 years. And what did that record reveal?

The six scientists report that (1) prior to the year 100 CE (= 100 AD) -- which they say was contemporaneous with the end of the Roman Warm Period -- "winter temperatures were more than 1.5°C warmer than today," that (2) "from 100 to 450 CE, highly variable temperatures indicate a transition phase," that (3) "after 450 CE, winter temperatures are constantly lower," while (4) the "highest temperatures during this interval occurred around 950 CE concomitant with the Medieval Warm Period."

The significance of these observations lies primarily in the fact that they provide yet another demonstration of the existence of two multi-century periods of time -- the Medieval and Roman Warm Periods -- when the earth was significantly warmer than it is currently, and at times when the atmosphere's CO2 concentration was significantly less than what it is today.

Posted 26 February 2016