Sol’s protracted solar minimum, which began about 2007, has opened the inner solar system to the highest concentration of cosmic rays yet measured during the space age (about fifty years old).
Which should provide a good test of Danish scientist Henrik Svensmark’s theory that cosmic rays provide seed nuclei for the low-altitude clouds that keep Earth’s temperature low. The theory is an alternative to the carbon dioxide argument, in that fewer cosmic rays hitting Earth would mean fewer low-level clouds and thus correspondingly higher temperatures. If Svensmark’s theory–explained in his 2008 book The Chilling Stars–is correct, winters could become more severe. At least until Sol’s minimum turns back to maximum.