Northern hemisphere temperature variability for the past three centuries: Tree-ring and model estimates

We compare Northern Hemisphere energy-balance-model temperature calculation s to an annual temperature reconstruction based on 20 tree-ring width recor ds from latitudinal and elevational treeline sites in northern North Americ a, Scandinavia, Siberia and Mongolia for the past three centuries. The ener gy-balance model uses three primary forcings; solar, volcanic, and anthropo genic trace gas and aerosol variations. Several different parameterizations of the forcings are compared. The best agreement (r = 0.8) is found when t he annual reconstruction is compared to a version of the model using (1) th e Dust Veil Index of Lamb, (2) a solar parameterization which includes the length of the solar cycle, and (3) anthropogenic forcing. The implication i s that all three forcings are important in explaining the temperature varia tions. The general similarity in low-frequency trends between the two indep endently-derived time series supports the validity of both the model estima tes and the tree-ring reconstruction.