Earth is experiencing a sunspot drought which, if it persists, may deliver a make-or-break test of the theory of anthropogenic global warming (AGW).
Along with a dearth of sunspots, NASA reports other signs of a current lull in the sun’s activity, including a 50-year low in solar wind pressure and a 12-year low in the sun’s brightness.
Some scientists believe that these signs point to more than just a low point in the 11-year solar cycle. The sun may be entering a “deep solar minimum”.
Previous solar minimums – the Maunder Minimum of 1645-1715, the Sörer Minimum of 1460-1550 and the Dalton Minimum of 1790-1830 – coincided with periods when Earth’s climate was colder than average.
While the link between solar minimums and a dip in global temperature isn’t fully established, some believe a solar minimum over the next couple of decades may be a litmus test of whether greenhouse gas emissions are the primary cause of Earth’s sudden warming.