Benestad and Schmidt 2009
Benestad, R.E., and, 2009: Solar trends and global warming. J. Geophys. Res., 114, D14101, doi:10.1029/2008JD011639.
We use a suite of global climate model simulations for the 20th Century to assess the contribution of solar forcing to the past trends in the global mean temperature. In particular we examine how robust different published methodologies are at detecting and attributing solar-related climate change in the presence of intrinsic climate variability and multiple forcings. We demonstrate that naive application of linear analytical methods such as regression gives non-robust results. We also demonstrate that the methodologies used in Scafetta & West [2005, 2006a, b, 2007, 2008] are not robust to these same factors and that their error bars are significantly larger than reported. Our analysis shows that the most likely contribution from solar forcing a global warming is 7±1% for the 20th Century, and is negligible for the warming since 1980.