A new contribution has appeared with respect to the solar forcing of the climate system. We recently presented a weblog on solar forcing (see), and this paper updates the scientific investigation of this subject. This 2006 paper by N. Scafetta and B. J. West is
” Phenomenological solar contribution to the 1900â2000 global surface warming, Geophys. Res. Lett., 33, L05708, doi:10.1029/2005GL025539. ”
The abstract states,
“We study the role of solar forcing on global surface temperature during four periods of the industrial era (1900â2000, 1900â1950, 1950â2000 and 1980â2000) by using a sun-climate coupling model based on four scale-dependent empirical climate sensitive parameters to solar variations. We use two alternative total solar irradiance satellite composites, ACRIM and PMOD, and a total solar irradiance proxy reconstruction. We estimate that the sun contributed as much as 45â50% of the 1900â2000 global warming, and 25â35% of the 1980â2000 global warming. These results, while confirming that anthropogenic-added climate forcing might have progressively played a dominant role in climate change during the last century, also suggest that the solar impact on climate change during the same period is significantly stronger than what some theoretical models have predicted. ”
This study, if confirmed, indicates that the current natural forcing of the climate syatem is more variable than has been claimed in the IPCC assessments, and most recently in the CCSP Report “âTemperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differencesâ?.