John McCain walks a fine line on the environment The television ad shows John McCain, the Republican presidential nominee, in scenic desert landscapes as he talks about the dangers of global warming. "We have an obligation to future generations to take action and fix it," he says. Striving to appeal to moderate voters, McCain has frequently highlighted his bipartisan proposal to clamp down on greenhouse gas emissions. But by naming Sarah Palin as his running mate, McCain has aligned himself with a Republican whose record as governor of Alaska has drawn scorn from environmentalists, most notably for her denial that humans are causing climate change. That, combined with McCain's call for opening new stretches of coastline to oil drilling, risks undercutting his standing on the environment....