Read here. Scientists analyzing maximum latewood density (MXD) datasets from Scandinavia determine that the Medieval Warming was unprecedented in its duration, at least 100 years in length.
In contrast to the modern era, this study, by Gunnarson et al., revealed that there were similar temperature increases from 1910 to 1940's, and one that started in the late 1990's. Neither of these very short-term warmings have MDX temperature reconstructions exceeding the Medieval Period.
"Working in the same general area, researchers combined these older historical MXD data with "recently collected MXD data covering AD 1292-2006 into a single reconstruction of April-September temperatures for the period AD 1107-2006,".....report "there is a steep increase in inferred temperatures at the beginning of the twelfth century, followed by a century of warm temperatures (ca. 1150-1250)," which falls within the temporal confines of the Medieval Warm Period; and they state that "the record ends with a sharp increase in temperatures from around 1910 to the 1940s, followed by decreasing temperatures for a few decades," after which they indicate that "another sharp increase in April-September temperature commenced in the late 1990s," during what is commonly known as the Current Warm Period. Thus, they say that "the two warmest periods are the mid to late twentieth century and the period from AD 1150-1250," and they emphasize that the temperatures of both of these periods have been so similar that "it is not possible to conclude whether the present and relatively recent past are warmer than the 1150-1250 period."" [Björn E. Gunnarson, Hans W. Linderholm, Anders Moberg, 2011: Climate Dynamics]
Additional climate-history and peer-reviewed postings. Historical temperature charts.
