Cooling down the world's cities, one rooftop at a time.

Colorado is about to let residents collect rainwater, but the debate is far from over.

It's not necessarily a good thing.

Market trends and new regulations spell the end for one of America's dominant sources of energy.

As oil prices go down, so does concern for the environment.

The historic climate agreement struck in December has yet to be signed, and already has suffered one setback after another.