Much of the East Coast is shut down today as residents prepare for Hurricane Sandy, a massive storm that could impact up to 50 million people from the Carolinas to Boston. The storm has already killed 66 people in the Caribbean, where it battered Haiti and Cuba. "This thing is stitched together from elements natural and unnatural, and it seems poised to cause real havoc," says Bill McKibben, founder of 350.org. New York and other cities have shut down schools and transit systems. Hundreds of thousands of people have already been evacuated. Millions could lose power over the next day. Meteorologists say Sandy could be the largest storm ever to hit the U.S. mainland. The megastorm comes at a time when President Obama and Republican challenger Mitt Romney have refused to make climate change an issue on the campaign trail. For the first time since 1984, climate change was never addressed during a presidential debate. "It’s really important that everybody, even those who aren’t in the kind of path of this storm, reflect about what it means that in the warmest year in U.S. history, ... in a year when we saw, essentially, summer sea ice in the Arctic just vanish before our eyes, what it means that we’re now seeing storms of this unprecedented magnitude," McKibben says. "If there was ever a wake-up call, this is it."