ScienceDaily: Not only has the average global temperature increased in the past 50 years, but the hottest day of the year has shifted nearly two days earlier, according to a new study by scientists from the University of California, Berkeley, and Harvard University. Just as human-generated greenhouse gases appear to the be the cause of global warming, human activity may also be the cause of the shift in the cycle of seasons, according to Alexander R. Stine, a graduate student in UC Berkeley’s …