what could be the simplest explanation for one component of global warming, a new study shows the Sun's radiation has increased by .05 percent per decade since the late 1970s. The increase would only be significant to Earth's climate if it has been going on for a century or more, said study leader Richard Willson, a Columbia University researcher also affiliated with NASA's Goddard Institute for Space Studies. The Sun's increasing output has only been monitored with precision since satellite technology allowed necessary observations. Willson is not sure if the trend extends further back in time, but other studies suggest...