The drought that has gripped the American Southwest since 2000 is as bad as or worse than droughts in the region over the past 1,200 years, a new Columbia-led study finds.

Shutting off a large portion of the economy serves as a natural control experiment by creating a world that has very few emissions, says Dan Westervelt, a climate and air-pollution researcher at Columbia's Lamont–Doherty Earth Observatory.

Elena Aprile, a Columbia University physics professor, leads the Xenon experiment, one of the world’s largest and most expensive investigations into the nature of dark matter.

A new tracking study led by Columbia University scientists suggests the birds are responding to the dwindling snow cover on their migratory flight path.

"There will be adequate food, even if some prices are higher and some items become temporarily unavailable," said Michael Puma, director of the Center for Climate Systems Research at Columbia University’s Earth Institute.

In New York, carbon monoxide levels were down by nearly 50 percent from the previous year, according to an analysis by Columbia atmospheric scientist Róisín Commane and her colleagues.