This TED Talk features inventors, scientist, author, and engineer Danny Hillis, recorded live at TED 2017.

What if there was a way to build a thermostat that allowed you to turn down the temperature of the earth anytime you want it?

Now, you would think if somebody had a plausible idea

about how to do that,

everybody would be very excited about it

and there'd be lots of research on how to do it.

But in fact, a lot of people do understand how to do that,

but there's not much support for research in this area. And I think part of it is because

there are some real misunderstandings about it. So I'm not going to try to convince you today

that this is a good idea, but I am going to try to get your curiosity going about it

and clear up some of the misunderstandings.

So the basic idea of solar geoengineering

is that we can cool things down

just by reflecting a little bit more sunlight back in the space.

And ideas about how to do this have been around literally for decades.

Clouds are a great way to do that, these low-lying clouds. Everybody knows it's cooler under a cloud.

I like this cloud because it has exactly the same water content

as the transparent air around it.

And it just shows that even a little bit of a change

in the flow of the air can cause a cloud to form.

We make artificial clouds all the time.

These are contrails, which are artificial water clouds

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