May I have your attention please you can now book your train tickets on Uber and get

10% back in credits to spend on your next Uber ride so you don't have to walk home in the brain again.

Trains, now on Uber. T's and C's Science. I'm Suzanne Bard.

Airplane. Airplane's account for about 3% of the climate-altering carbon dioxide emissions

we add to the atmosphere, but planes are warming the planet in another way.

So if you look up in the sky, you probably see at some point an aircraft, and behind that aircraft

are white fluffy streaks, and that's what we call the Contrail.

Imperial College London engineer Mark Stetler.

Contrails are made up of ice crystals that form when aircraft engines emit exhaust that hits the cold air. The ice crystals reflect incoming light

from the sun back into space, which has a cooling effect on the atmosphere. But the contrails also

stop heat coming up from the ground from escaping into space.

It's reflected back down towards the ground and so that's a warming effect.

Stetler says on balance, Contrails warm the atmosphere more than they cool it.

And that's primarily because the cooling effect due to reflecting of sunlight can only happen during the day when the sun's shining.

Whereas the warming effect due to trapping of outgoing heat happens all of the time.

Some contrails can form clouds that last for up to 18 hours. During that time they spread out,

trapping even more heat. This process allows

Contrails to warm the planet about as much as the carbon dioxide emissions from

aircraft. But when Stettler and his team analyze flight data they obtained of Japan airspace,

they found that most contrail warming was caused by just 2% of flights,

and most of those flights originated in the late afternoon,

because as the sun goes down cooling

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