This TED Talk features climate innovation activist Kelly Wanzer, recorded live at TED Summit 2019.

I'm here to talk to you about something important that may be new to you.

The governments of the world are about to conduct an unintentional experiment on our climate.

In 2020, new rules will require ships to lower their sulfur emissions

by scrubbing their dirty exhaust or switching to cleaner fuels.

For human health, this is really good.

But sulfur particles in the emission of ships also have an effect on clouds.

The streets in the clouds are created by the exhaust from ships.

Ships emissions include both greenhouse gases which trap heat over long periods of time,

and particulates like sulfates that mix with clouds and temporarily make them brighter.

Brighter clouds reflect more sunlight back to space,

cooling the climate.

So, in fact, humans are currently running two unintentional experiments on our climate.

And the first one, we're increasing the concentration of greenhouse gases

and gradually warming the Earth system.

This works something like a fever in the human body. If the fever remains low, its effects are mild.

But as the fever rises, damage grows more severe and eventually devastating.

We're seeing a little of this now.

In our other experiment, we're planning to remove a layer of particles that brighten clouds and shield us from some of this now. In our other experiment, we're planning to remove a layer of particles

that brighten clouds and shield us from some of this warming. The effect is strongest in ocean

clouds like these, and scientists expect the reduction of sulfur emissions from ships next year

to produce a measurable increase in global warming.

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