In the scientific debate on global warming and the sun/cosmic rays relations, Friis-Christensen et al. have produced several fascinating and inspiring ideas. New and alternative ideas are always welcome and they deserve recognition for their contribution. Not all ideas have passed the test by the scientific community. However, it is clear that they have started a scientific debate and as well as a blog debate on solar influence and cosmic rays.
Friis-Christensen et al. investigated the relation between solar cycle length and global temperature in their 1991 paper. They found a close relation between solar cycle length and global temperature for the years 1850-1985. As I understand it, they have been doing a data mining exercise and found this relation. However, their result could not be supported by scientific evidence. Data mining is OK in some cases, but there is a risk to detect flawed relations. The result was consequently challenged by Peter Laut in 2003. Peter Laut has publicly criticized Friis-Christensen for adjusting data in an improper way. As a consequence there was at heated debate.
Recently P. Stauning has produced a paper where he has updated data and expanded same graphics, now from 1850 to 2005, and corrected the calculation errors of Friis-Christensen et al. The result of this update is that the close relation from 1850 through 1985 has stopped and from 1985 the solar cycle length curve and the temperature curve are diverging.