AP: Sen. Russ Feingold is criticizing his likely GOP challenger’s views on climate change. Feingold’s comments Monday came after Oshkosh businessman Ron Johnson said the science of human-caused climate change hasn’t been proven. Johnson says climate change might be due to sunspots. Feingold told reporters at the Milwaukee Press Club that Johnson’s explanation is “not credible.” Feingold says Johnson is distorting the problem with unscientific claims. Sara Sendek is a …