Guardian: Today marks the 40th anniversary of Earth Day. Approximately 1 billion people will participate in Earth Day celebrations this month, and today alone countless people will plant trees, clean up rivers, pledge not to use plastic bags and decide to walk rather than drive. All of this helps, of course, but it’s not going to save the planet. To be truly “green”, we’ve got to make our diets more environmentally friendly by kicking the meat habit and going vegan. An apple a day can help keep …