NPR – August 8, 2013
Plant life on our planet soaks up a fair amount of the carbon dioxide that pours out of our tailpipes and smokestacks. Plants take it up during the summer and return some of it to the air in the winter. And a new study shows that those “breaths” have gotten deeper over the past 50 years….
http://www.npr.org/2013/08/08/210243967/swinging-co2-levels-show-the-earth-is-breathing-more-deeply?sc=17&f=1001