This is Scientific American 60-Second Earth. I'm David Biello. Your minute begins now.
Remember when a barrel of oil cost more than $140?
That was way back in 2008.
Nowadays, cars and trucks have been made to go farther on less fuel.
Alternatives like ethanol have boomed.
And fracking has unleashed a flood of oil formerly trapped in shale rock underneath North Dakota, among other places.
As a result, oil prices have fallen, far.
The price of a barrel of oil has dropped below $60.
But what's good news for drivers is bad news for the global bid to cut climate changing pollution.
Burning oil in vehicles is the second largest source of fossil fuel pollution.
It's also bad news for alternatives, like new facilities that turn corn stalks into ethanol.
Hybrids and electric cars are less popular when gas is cheaper.
In fact, the sport-utility vehicles of yesteryear are staging a comeback.
But back on the good news front: a falling price of oil reduces the incentive to do expensive things to get the liquid fossil fuel, like drill in the Arctic or mine Canada's boreal forest for tar sands.
Of course, in the long run oil prices are likely to go back up.
It's just a question of how much environmental damage gets done before that happens.
Your minute is up, for Scientific American 60-Second Earth. I'm David Biello.