Climate Dynamics DOI 10.1007/s00382-002-0270-8 Constraining temperature variations over the last

• Main Authors: S. Gerber, F. Joos, P. Brügger, T. F. Stocker, M. E. Mann, S. Sitch, M. Scholze
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.408.1086; http://www.meteo.psu.edu/holocene/public_html/shared/articles/GerberClimDyn02.pdf

Abstract. The response of atmospheric CO 2 and climate to the reconstructed variability in solar irradiance and radiative forcing by volcanoes over the last millennium is examined by applying a coupled physical-biogeochemical climate model that includes the Lund-Potsdam-Jena dynamic global vegetation model (LPJ-DGVM) and a simplified analogue of a coupled atmosphere-ocean general circulation model. The modeled variations of atmospheric CO 2 and Northern Hemisphere (NH) mean surface temperature are compatible with reconstructions from different Antarctic ice cores and temperature proxy data. Simulations where the magnitude of solar irradiance changes is increased yield a mismatch between model results and CO 2 data, providing evidence for modest changes in solar irradiance and global mean temperatures over the past millennium and arguing against a significant amplification of the response of global or hemispheric annual mean temperature to solar forcing. Linear regression (r = 0.97) between modeled changes in atmospheric CO 2 and NH mean surface temperature yields a CO 2 increase of about 12 ppm for a temperature increase of 1 °C and associated precipitation and cloud cover changes. Then, the CO 2 data range of 12 ppm implies that multi-decadal NH temperature changes between 1100 and 1700 AD had to be within 1 °C. Modeled preindustrial variations in atmospheric