The EPA and State Department have now clashed over the proposed pipeline twice in two years, muddling recent indications that its approval might be imminent.
In honor of the Earth Day season, NASA has released an awe-inspiring video of the best imagery captured by its Earth-observing satellites over the past year.
Three years after the worst oil spill in American history, the Gulf of Mexico is shifting from acute aftermath to the uncharted waters of long-term rehab.
The first graduating class of 'wildlife detector dogs' will soon be stationed at ports around the U.S., part of a growing effort to stem the illegal trade of flora and fauna.
Anonymously added to a recent budget bill, the controversial rider would protect U.S. biotech companies from litigation if their GMO seeds turn out to be dangerous.
After 46 years at the space agency, one of America's most famous climate scientists will now focus on rallying support for the fight against climate change.
A solar eruption slammed into Earth earlier this month, sparking a vivid aurora display that photographer Göran Strand caught in this all-sky time-lapse video.