Decarbonizing Aviation and Contrail Impact

One of the hardest parts of the economy to decarbonize will be

aviation. Aviation creates warming in two ways.

The first is CO2 emitted from the jet fuel that's burned.

To reduce that, battery-powered planes can come in with

limited range, and over time we'll develop sustainable

aviation fuels, that is plug-in fuels with net zero carbon

emissions. But the second part of

aviation warming comes not from the fuels, but

actually from the contrails. These are the clouds that you'll

sometimes see behind the plane as they fly.

Those are not emissions, they're clouds.

What's going on is that if a plane flies through an

area that the humidity, the water saturation of

the air in that area is high, then the particles that come out of

the jet engine allow ice crystals to form,

and that's what you see when you see those long white

clouds trailing behind a jet plane.

Those clouds, those human-made cirrus clouds,

are half of the temperature increase caused by aviation,

and they really trap the heat that's coming out of the earth.

If the path that the plane takes avoids those parts of the

sky where you have lots of water, where you have that humidity, then you

avoid forming the contrails. Figuring out in

advance where the contrail-forming areas are

and bringing data to the pilot, they can adjust

their altitude to avoid those areas.

They already do this to steer around thunder clouds or areas with high

turbulence. Small changes in altitude, either go below it or to go

above it, require the least deviation.

And the airline industry is engaged on this issue.

So it means that for a very modest cost, we can

eliminate almost 2% of all global warming.

I mean, it's really unbelievable, and it's also an example of

really great partnerships being built around this work.

And with the right cooperation, we can scale this

out and have a massive impact.