Changes in the Sun's brightness over the past millennium have had only a small effect on Earth's climate, according to a review of existing results and new calculations performed by researchers in the United States, Switzerland, and Germany.
In this image from an active solar period in March 2001, colors are shifted to highlight the contrast between sunspots (black and dark red) and the faculae that surround them (bright yellow). During the peak of the 11-year solar cycle, the expansion of faculae outweighs the darkening from increased sunspot activity. The result is a net increase in solar brightness. (Image courtesy of NASA)
The review, led by Peter Foukal (Heliophysics, Inc.), appears in the September 14 issue of Nature. Among the coauthors is Tom Wigley of the National Center for Atmospheric Research. NCAR's primary sponsor is the National Science Foundation.
"Our results imply that, over the past century, climate change due to human influences must far outweigh the effects of changes in the Sun's brightness," says Wigley.
Not that facts matter, but it does put the nit in nitwit.