Read here. A peer-reviewed study documents the extremely warm temperatures of the Medieval Period that occurred in the California Sierra Nevada range. Scientists, working with dead tree trunks located above the current treeline, affirm California's Medieval extreme warm temperature history, which still remains unprecedented.
"Working with dead tree trunks located above the current treeline on tephra-covered slopes of Whitewing Mountain and San Joaquin Ridge.....the five researchers say "the Medieval forest on Whitewing was growing under mild, favorable conditions (warm with adequate moisture)," as indicated by "extremely low mean sensitivities [to stress] and large average ring widths." More specifically, they conclude, as reported in their abstract, that annual minimum temperatures during the Medieval Climatic Anomaly in the region they studied were "significantly warmer" (+3.2°C) "than present,".....Once again, we have another example of a paleoclimate study in which the Medieval Warm Period is determined to have been significantly warmer than it is currently....."
Additional historical temperature charts. Climate history postings. Modern temperature charts.