Is taking along a couple of re-usable bags on my next trip to the grocery store or swapping out a few standard light bulbs for CFL's really going to save the world?  A few years ago, I interviewed a leading climatologist at NASA for a children's nonfiction book I was writing. When I asked her to share some tips, things kids could do to help nurture the planet, she surprised me by saying, "It's too late." Our changing climate today, she revealed, was the result of decades of pollution and...