How does rising atmospheric CO2 affect marine organisms?

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Boothia Peninsula, Nunavut, Canada
Zabenskie, S. and Gajewski, K. 2007. Post-glacial climatic change on Boothia Peninsula, Nunavut, Canada. Quaternary Research 68: 261-270.

Sediment cores were extracted from Lake JR01 (6954'N, 954.2'W) on the Boothia Peninsula, Nunavut, Canada, using a Livinstone corer, with the authors careful to note that "the uppermost part of the sediment was sampled in a plastic tube with piston to ensure that the sediment-water interface was collected," while further stating that "the upper 20 cm of sediment were sub-sampled into plastic bags at 0.5-cm intervals." Then, from the fossil pollen assemblages thereby derived, July temperatures were estimated "using the modern analog technique." Among other things, this work revealed "a short warming," which they say "could be interpreted as the Medieval Warm Period." Following this latter period of warmth, they found that "temperatures cooled during the Little Ice Age," as pollen percentages "returned to their values before the [MWP] warming." Last of all, during the final 150 years of the record, a "diverse and productive diatom flora" was observed. However, as the two researchers continue, "July temperatures reconstructed using the modern analog technique remained stable during this time," which suggests that this part of the world is currently not as warm as it was during the MWP. In fact, from data presented in their Figure 7, we calculate that peak MWP temperatures were fully 1.0C warmer than it is currently, and that the MWP occurred between AD 1200 and 1500.