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Home » How Aerosols Brighten Clouds — and Cool the Planet: Sarah J. Doherty (Transcript)

How Aerosols Brighten Clouds — and Cool the Planet: Sarah J. Doherty (Transcript)

Here is the full transcript of atmospheric scientist Sarah J. Doherty’s talk titled “How Aerosols Brighten Clouds — and Cool the Planet” at TED 2024 conference.

Listen to the audio version here:

TRANSCRIPT:

So I’m a climate scientist, and based on that, I bet you think I’m here to tell you about all the ways that we’re making the climate warmer. But I’m not actually going to do that today because I think you already know that part of the story. I want to tell you instead a story about unintended consequences.

For many of us, it’s really easy to forget that in addition to emitting a lot of greenhouse gases, humans have been adding a lot of particulate pollution to the atmosphere. These small particles, which we scientists call aerosols, are responsible for the death of between four and 10 million people a year around the globe. For much of the world, this remains a major public health crisis.

And because of that, there are significant efforts underway to clean up the source of these emissions, which is fantastic. But here’s the thing. The unintended consequence of doing that is that we might actually be accelerating climate warming.

The Cooling Effect of Aerosols

And that’s because most of these aerosols actually cool climate. I spent my career as a climate scientist studying how aerosols in the atmosphere around the globe absorb sunlight in the atmosphere and increase the reflection of sunlight away from our planet. Aerosols directly scatter sunlight back to space, and when they mix into clouds, they can make clouds brighter or more reflective.

And both of these effects act to cool the climate by reducing the amount of sunlight that’s available to heat the surface. We estimate that right now, aerosols from human activities are cooling climate by about half a degree Celsius. In other words, if it weren’t for these climate effects, we would already be experiencing significantly worse climate impacts than we already are.

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