Don't count on forests to keep us cool. Learn more about how trees in the far northern forests have been growing more slowly in the summertime.

B.L. Turner is a professor at Arizona State University. He talks about the history of the biophysical system and the social system as one of a coupled system.

There is no consensus on desirable levels of consumption, or even what "sustainable consumption" looks like. Read more with Alex de Sherbinin.

On July 2, 2006, asteroid 2004 XP14 passed not much farther than the moon's average distance from Earth. There is no danger of this asteroid striking Earth in the foreseeable future. But astronomers - like Judit Ries of the University of Texas - now know and study hundreds of other Near-Earth Objects like 2004 XP14.