Spatial and temporal characteristics of climate in Medieval times revisited

Diaz H.F., Trigo R.M., Hughes M.K. Mann M.E., Xoplaki E., Barriopedro D.
Bulletin of American Meteorological Society. doi: 10.1175/BAMS-D-10-05003.1., 92, 1487-1500

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Climate in medieval times, a period usually understood to extend from A.D. ~950 to ~1400, is of considerable interest to students of modern and future climate. This is because the period differs from recent centuries mainly by predating the Industrial Revolution with its associated changes in the composition of the atmosphere and oceans and the nature of the land surface (Hughes and Diaz 1994; Crowley and Lowery 2000; Bradley et al. 2003a,b). In this sense it represents an appealing, but imperfect "control case" for the unintended global climate experiment that has resulted from industrial and agricultural development and population growth. In order to stimulate a synthesis of recent work on these topics, we convened a meeting of international experts to consider the following issues:
  1. What were some of the key regional patterns of climatic anomalies during medieval times derived from the proxy climate records and from model simulations, and how do they compare with the twentieth-century patterns?
  2. Recognizing that multiple proxy climate records are needed to constrain as much as possible the spatial and temporal variability of climate, what do recent studies using powerful statistical methods tell us about the timing and geographic coverage of the major features of climate in medieval times?
  3. A number of numerical simulations using climate models of varying complexity and external forcing histories have been completed in the past few years. What do the latest model results tell us about geographic patterns and temporal characteristics of the simulated climate of this period?
  4. In what specific ways does the climate of the last several decades (approximately the last 30 years) differ from periods of comparable length in medieval times?