A timescale analysis of the Northern Hemisphere temperature response to volcanic and solar forcing

[摘要] The Northern Hemisphere temperature responseto volcanic and solar forcing in the time interval 1000–1850 AD isstudied using first aset of simulations with an intermediate-complexity climate model, driven byreconstructed forcings. Results are then compared with those obtained fromthe seven high-resolution reconstructed temperature records for the lastmillenium that are at present available. Focus of theanalysis is on the timescale dependence of the response. Results between themodel and the proxy-based reconstructions are remarkablyconsistent. The response to solar forcing is found to equilibrate atinterdecadal timescales, reaching an equilibrium value for the regressionof 0.2–0.3°C per W/m². The time interval between volcaniceruptions is typically shorter than the dissipation timescale of theclimate system, so that the response to volcanic forcingnever equilibrates. As a result, the regression on the volcanicforcing is always lower than theequilibrium value and goes to zero for the longest temporal scales.The trends over the pre-anthropogenic period are found to be relatively largein all reconstructed temperature records, given the trends in thereconstructed forcing and the equilibrium value for the regression.This is at variance with a recentclaim that reconstructed temperature records underestimate climatic variationsat multi-centennial timescales.

[学科分类] 大气科学