Science:
If rising levels of greenhouse gases aren't pushing up global
temperatures, as contrarians argue, what else could be? The
leading alternative has been a fickle sun, and the sun's most
likelyâmdash;or most heavily
promotedâmdash;agent of change has been cosmic
rays. Now scientists have published the first comprehensive
modeling of how the sun might indirectly thin cloud cover and
thus warm the planet. It suggests that cosmic rays are not up
to the task by two orders of magnitude. "It's a really good f
irst study," says modeler Dominick Spracklen of the University
of Leeds, U.K., but "the first attempt is always going to be
uncertain. There's going to be debate."
