A great number of papers on that list merely studies natural influence (or 'forcing') of the terrestrial climate. These natural factors have been (and are being) studied and quantified, and in the vast majority of cases they imply changes of different (mostly smaller) magnitude that happen on different time scales and that are out of phase with the climate change observed currently. Anthropogenic emissions of greenhouse gases (and other pollutants), by contrast, are released at rate more comparable to the rate of climate change, are happening in phase and on the same time scale, and have associated climate forcing large enough to account for the rate of warming. To study (and propose) natural climate drivers is not equivalent to disputing anthropogenic drivers. It has actually become hard to study 'natural climate variations' because of contamination by man-made aerosols/emissions. We resort now to paleo-records, planetary proxies, or 'seek pristine' areas for suitable laboratories.