A vivid picture of our climate's future can be found in our past. Currently, atmospheric carbon dioxide (CO2) levels have reached 390 parts per million (ppm). The last time CO2 was that high was around 3 million years ago, in the early Pliocene. Back t...

photo: www.bluewaikiki.com/Creative Commons In case you were holding out hope that all that extra CO2 we're pumping into the atmosphere would stimulate enough extra plant growth to balance out any future increases in global temperature, give it up: N...