By Dan Shapley
Hillary Clinton will mark Earth Day today by making her campaign carbon neutral. She is the third presidential candidate to go carbon neutral. Tom Vilsack took that step in February, and John Edwards did in March. "In order to address the climate crisis, we all must act -- and that includes our campaign," Clinton said in a press release. "As a nation, it is past time that we met this challenge head-on by increasing energy efficiency and investments in clean and renewable energy. If we do nothing, the planet will continue to warm over the next century, with widespread and potentially devastating effects."