Read here. Map source here. A new peer-reviewed study (Clegg et al.) firmly establishes that modern global warming is significantly less than the global warming experienced in the high latitudes, during the summers of multiple periods over the last 3,000 years. Specifically, historical global warming is still unprecedented, and modern warming is a blip in comparison. (click on images to enlarge)
"The authors conducted a high-resolution analysis of midge assemblages found in the sediments of Moose Lake in the Wrangell-St. Elias National Park and Preserve.....The results of the study are portrayed in the accompanying figure, where it can be seen, in the words of Clegg et al., that "a piecewise linear regression analysis identifies a significant change point at ca 4000 years before present (cal BP)," with "a decreasing trend after this point." And from 2500 cal BP to the present, there is a clear multi-centennial oscillation about the declining trend line, with its peaks and valleys defining the temporal locations of the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period, the Little Ice Age.....and, finally, the start of the Current Warm Period, which is still not expressed to any significant degree compared to the Medieval and Roman Warm Periods." [Benjamin F. Clegg, Gina H. Clarke, Melissa L. Chipman, Michael Chou, Ian R. Walker, Willy Tinner, Feng Sheng Hu 2010: Quaternary Science Reviews]
Additional climate-history postings. More peer-reviewed postings. Historical and modern temperature charts.
