THE MEDIEVAL SOLAR-ACTIVITY MAXIMUM

Paleoclimatic studies of the Medieval Solar Maximum (c. A.D. 1100-1250 , corresponding with the span of the Medieval Warm Epoch) may prove us eful because it provides a better analog to the present solar forcing than the intervening era. The Medieval Solar Activity Maximum caused t he cosmogenic isotope production minimum during the 12th and 13th Cent uries A.D. reflected by DELTAC-14 and Be-10 records stored in natural archives. These records suggest solar activity has returned to Medieva l Solar Maximum highs after a prolonged period of reduced solar activi ty. Climate forcing by increased solar activity may explain some of th is century's temperature rise without assuming unacceptably high clima te sensitivity. By analogy with the Medieval Solar Activity Maximum, t he contemporary solar activity maximum may be projected to last for 15 0 years. The maximum temperature increase forced by increased solar ac tivity stays well below the predicted doubled atmospheric CO2 greenhou se forcing.