New York Times: Summer fire seasons in the great forests of the West have always hinged on elements of chance: a heat wave in August, a random lightning strike, a passing storm front that whips a small fire into an inferno or dampens it with cooling rain. But tiny bark beetles, munching and killing pine trees by the millions from Colorado to Canada, are now increasingly adding their own new dynamic. As the height of summer fire season approaches, more than seven million acres of forest in the United …