Medieval Warm Period (“MWP”)

Period of relative warmth in some regions of the Northern Hemisphere in comparison with the subsequent several centuries. Also referred to as the Medieval Warm Epoch (MWE). As with the ‘Little Ice Age’ (LIA), no well-defined precise date range exists. The dates A.D. 900–1300 cover most ranges generally used in the literature. Origin is difficult to track down, but it is believed to have been first used in the 1960s (probably by Lamb in 1965). As with the LIA, the attribution of the term at regional scales is complicated by significant regional variations in temperature changes, and the utility of the term in describing regional climate changes in past centuries has been questioned in the literature. As with the LIA, numerous myths can still be found in the literature with regard to the details of this climate period. These include the citation of the cultivation of vines in Medieval England, and the settlement of Iceland and southwestern Greenland about 1000 years ago, as evidence of unusual warmth at this time. As noted by Jones and Mann (2004) [Jones, P.D., Mann, M.E., Climate Over Past Millennia, Reviews of Geophysics, 42, RG2002, doi: 10.1029/2003RG000143, 2004], arguments that such evidence supports anomalous global warmth during this time period is based on faulty logic and/or misinterpretations of the available evidence.