Paper Reviewed
Ouellet-Bernier, M.-M., de Vernal, A., Hillaire-Marcel, C. and Moros, M. 2014. Paleoceanographic changes in the Disko Bugt area, West Greenland, during the Holocene. The Holocene 24: 1573-1583.

Can you guess how much warmer it was in west Greenland during the 200-year-long Medieval Warm Period than it is today?

Providing the answere to this question was Ouellet-Bernier et al. (2014), who conducted several micro-paleontological analyses of a marine sediment core extracted from Disko Bugt (West of Greenland) in order to document paleo-oceanographical changes in the eastern part of Baffin Bay during the Holocene. Prominent among these analyses was the modern analogue technique, which they applied to dinocyst assemblages that provided information on paleo-sea-surface conditions, whereas isotopic analyses of benthic foraminifers were employed to assess the characteristics of the deep water mass occupying the site.

These efforts revealed the existence of a number of periods of alternating cold and warm sea surface temperatures (SSTs) throughout the Holocene, the last of which warm periods was the Medieval Warm Period that occurred between approximately 1000 and 800 years BP. And in reporting their findings, Ouellet-Bernier et al. say that during this period the region's "summer SSTs increased to about 10°C," which they describe as being "much higher than the present day summer SST of about 4.4°C at the coring site," as recorded in the World Ocean Database of the NODC (2001).

And a very special note should be made of this truly amazing level of warmth that occurred during a period of time when the atmosphere's CO2 concentration was only a mere 285 ppm compared to the 40%-greater 400 ppm of today, which facts clearly suggest that atmospheric CO2 concentrations have little to no impact on Earth's surface temperature.

Reference
NODC (National Oceanographic Data Center). 2001. World Ocean Database 2001. Scientific Data Sets, Observed and Standard Level Oceanographic Data. National Oceanic and Atmospheric Administration (NOAA), Boulder, Colorado, USA.