Phenomenological solar contribution to the 1900-2000 global surface warming

We study the role of solar forcing on global surface temperature during four periods of the industrial era (1900-2000, 1900-1950, 1950-2000 and 1980-2000) 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 45-50% of the 1900-2000 global warming, and 25-35% of the 1980-2000 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.