White House science adviser John Holdren, a Stanford-trained physicist who taught at UC Berkeley and has studied the effects of environmental change for much of his career, says President Obama will address climate change in his visit to Fresno on Friday. “You can certainly expect that the president will talk about the connection between the increasing frequency and intensity of droughts and climate change,” Holdren said Thursday in a conference call with reporters. Although droughts are common in the West, California’s current episode is among the strongest of the past 500 years, according to paleo-climate records, and the worst since...