Modeling the temperature response to forced climate change over the last six centuries

Development of improved proxy estimates of climate forcing and temperature change over the past six centuries provides a new opportunity to examine the role of forced variability in the climate system. We utilize an energy balance model to estimate that as much as 18-34% of low frequency temperature change over the preanthropogenic interval could be forced by volcanism and solar variability. Comparison of residuals with estimates of unforced variability from control runs of coupled models indicates that the spectra of the two time series agree at the 90% significance level.