Global Temperature Patterns

Abstract

Spatially resolved global reconstructions of annual surface temperature patterns over the past sixcenturies are based on the multivariate calibration of widely distributed high-resolution proxy climate indicators. Time-dependent correlations of the reconstructionswith time-series recordsrepresentingchangesin greenhouse-gasconcentrations, solar irradiance, and volcanic aerosols suggest that each of these factors has contributed to the climate variability of the past 400 years, with greenhouse gases emerging as the dominant forcing during the twentieth century. Northern Hemispheremeanannual temperatures for three of the past eight years arewarmerthan anyother year since (at least) AD 1400.