Dec 22, 2013

Small influence of solar variability on climate over the past millennium

Andrew P. Schurer, Simon F. B. Tett & Gabriele C. Hegerl
Nature Geoscience
  • States that:
    • The climate of the past millennium was marked by substantial decadal- and centennial-scale variability in the Northern Hemisphere
    • Low solar activity has been linked to cooling during the Little Ice Age (AD 1450–1850) and there may have been solar forcing of regional warmth during the Medieval Climate Anomaly (AD 950–1250)
    • The amplitude of the associated changes is, however, poorly constrained
  • Compares the climatic fingerprints of high and low solar forcing derived from model simulations with an ensemble of surface air temperature reconstructions for the past millennium
  • Accounts for internal climate variability and other external drivers such as volcanic eruptions, as well as proxy and model uncertainties
  • Finds that neither a high magnitude of solar forcing nor a strong climate effect of that forcing agree with the temperature reconstructions
  • Concludes that solar forcing probably had a minor effect on Northern Hemisphere climate over the past 1,000 years, while volcanic eruptions and changes in greenhouse gas concentrations seem to be the most important influence over this period