Scientific Ameircan: What better day to step back and take stock of the planet than Earth Day? Started in 1970 to raise awareness in the U.S. about the environmental state of the planet, Earth Day is now celebrated in more than 190 countries and has led to the creation of legislation in the U.S. aimed at protecting the environment. But one global trend has continued to alter the world--the rise of carbon dioxide and other greenhouse gas emissions, which have led to an ever-rising average global temperature.
It's easy...