Astronomers can play an important role in explaining the causes and consequences of climate change, says astrophysicist

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Hello, and welcome to the Physics World Weekly

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podcast.

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I'm Hamish Johnston.

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In this episode, we're going to be talking

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about climate change.

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Coming up a bit later, I'm in conversation

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with the author of cloudy with a chance

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of warming,

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how physicists

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are studying

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the dynamical

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impact

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of clouds on climate change, and that's a

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feature article that has just appeared on Physics

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World.

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But first, we're going to explore how astronomers

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can better understand climate change and share that

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knowledge with their students

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and the wider public.

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The book Climate Change for Astronomers,

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Causes,

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Consequences,

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and Communication

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was published earlier this year by IOP Publishing,

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which also brings you Physics World.

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The book weighs in at 527

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pages

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and features 19 chapters

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that were contributed

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by 20 scientists.

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The book was edited by Travis Rechter.

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He's an astrophysicist

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at the University of Alaska

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Anchorage

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and an advocate for solutions to climate change.

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Living in Alaska, he's witnessed dramatic changes in

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his home state, and this led him to

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cofound

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Astronomers

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for Planet Earth.

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Travis joins me down the line from Anchorage

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to talk about what astronomers can do in

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response to the climate crisis.

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Hello, Travis.

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Welcome to the podcast.

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Hello, and thank you for, inviting me today.

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So, Travis, what motivated you to edit climate

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change for astronomers?

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Why should astronomers teach climate change and talk

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about it with the general public?

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That's a good question. People are often surprised

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to hear that as an astronomer. I'm

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actively involved in advocating for climate change.

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And the reason why is because there's a

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a big overlap in the science of climate

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change and the science of astrophysics.

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And so

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in our astronomy classes for many years, myself

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and other astronomers have been teaching climate change

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as part of our curriculum. When you talk

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about, like, the atmosphere of Venus and why

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it's the hottest planet in the solar system,

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that naturally leads to questions from students about

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climate change. And so we're talking about climate

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change in our classes, and

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our goal is is to help people understand

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the science of it because often people

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don't hear about climate change from scientists. They

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hear about it from the news and social

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media.

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And so often in astronomy classes, the last

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opportunity

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for people to hear from a scientist about

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the actual science of it.

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And, Travis, one aim of the book is

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to give

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astronomers themselves a better understanding of climate change.

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How do you do this in the book?

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What topics do you focus on?

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Yeah. So for many years,

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we have been running workshops to help astronomers

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be effective teachers of our climate change, and

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I'd say the the most common concern

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that my fellow astronomers have is they feel

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like they don't know the science well enough.

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I've had people say to me, oh, I

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didn't really

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fully understand radiator transfer in grad school. I'm

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not sure I can effectively convey the science.

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And the key thing that I want all

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astronomers to know is is that no matter

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what you know, you already know enough to

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be an effective advocate

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for climate change solutions.

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But what many astronomers feel is that they

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want to know more, particularly when it comes

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to topics like the geologic history of the

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earth.

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There's a common misconception

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that,

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that

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climate change is a natural consequence of just

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natural fluctuations in the earth's climate. And so

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one of the chapters on the book is

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devoted to the earth's climate system

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to help astronomers

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be better able to teach the difference between

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natural causes of climate change and the human

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causes that are creating the crisis we're in

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right now.

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And the book also gives advice and suggestions

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for how astronomers can incorporate

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climate change into university astronomy courses.

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Can can you talk about some of the

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strategies that that can be pursued?

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Yeah. So

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there's so many ways in which our astronomy

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and physics courses

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touch on key concepts that are really important

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for people

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to help understand

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the problem. So,

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for example,

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simply understanding

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how long a 1000000000 years is

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can give people an understanding

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of the difference between

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natural climate change and this the long time

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scales on which it occurs

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and

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the and and the short term climate change

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that we're causing right now by using fossil

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fuels. There's many other examples. So, for example,

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talking about different kinds of light, if you're

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discussing infrared light versus optical light or if

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you're talking about spectroscopy

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and absorption features.

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These are all topics that naturally lead themselves

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to people being in a better position to

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understanding

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what causes climate change. It can also lead

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to a better understanding of solutions. So, for

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example, in a physics class,

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energy is a essential concept in every physics

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class. And so

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if people have

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a a fundamental understanding of how energy works

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and how it can be transitioned from one

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source of energy to another,

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then they're going to be in a better

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position to understand

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the many different solutions that are out there,

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whether it be wind or solar or nuclear

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and how these different energy sources can work

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together.

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I see. And and climate change for astronomers

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also looks at how the community can better

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communicate

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climate change to the public.

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What's the best practice when doing climate change

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related outreach? How do you get the message

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out to the general public?

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I think one of the biggest challenges that

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astronomers face when communicating with climate change, whether

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it be with students or the public,

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is understanding and appreciating

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that

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there are many different places again where people

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are hearing about climate change. It's not just

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from scientists. And as astronomers, we're

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accustomed to people being interested

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in hearing what we have to say. They

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love hearing about black holes and exoplanets

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and,

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life, beyond the earth. But then when you

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start talking about climate change, there's an additional

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element to it. It's emotionally charged. It's politically

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contentious,

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and there's a lot of feelings in the

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room. And so as scientists,

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we're accustomed to just simply telling people what

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we know and anticipating that they're going to

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accept that.

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And so it's very important for us

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to be good listeners. It's not something that

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we're often accustomed to doing. We're accustomed to

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being in front of an audience and and

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talking to people rather than listening.

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But if you take the time to listen

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to the questions people have, it'll give you

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a better sense of

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how they're feeling, what their concerns are, what

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maybe they've heard elsewhere,

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and give you a better opportunity

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to give them information that can help them.

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The most important thing, I think, in any

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interaction is for people to feel like that

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they were heard and they were listened to

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and respected

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and that they'll be interested in in learning

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more about it in the future either from

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you or from others. So

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having a positive interaction where people felt feel

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good afterwards is very important.

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I see. And and the book also looks

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at,

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the I suppose the vexing question

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of how astronomers can advocate for action

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on climate change without compromising their roles

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as scientists.

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And and that must be very difficult in

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in what you say has become a very

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polarized debate.

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How how how can scientists

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do that?

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Yeah. That's another common concern I hear from

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scientists is that

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they feel like they shouldn't enter the fray,

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that we should essentially be in our ivory

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tower from which we give information to people,

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but it is for others

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to to solve the problem. And I don't

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think that's true. I think there's a long

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history of scientists being advocates.

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And the reason why it's important for us

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to do it is because

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we need to share what we know

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to help people understand not only the problem,

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but what solutions are out there.

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Examples, obviously,

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Einstein was

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a major advocate for

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solutions about nuclear warfare.

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Carl Sagan is actually one of the first

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scientists to testify in front of congress about

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climate change back in the eighties.

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So

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what we can do as scientists that is

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share what we know and share how we

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understand

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different solutions

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to make

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decision makers in a better position to make

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good decisions. And so I don't think, as

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scientists, we should advocate for specific solutions or

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sole solutions. I don't think, as scientists,

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we should say that, for example, just wind

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power or just nuclear or just this or

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that is going to have a solution. But

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but by providing

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the information we have

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about all the different solutions are out there,

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then I think we can we can do,

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good to help people understand the problem. So

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one of the chapters we wrote in the

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book

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is just the just describes the pathways

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towards solutions. That is how can we go

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from the energy we use

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now to the energy we want,

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and what are the different ways that we

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can do that?

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And, Travis,

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Jeffrey Bennett, who's at the University of Colorado,

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has written a chapter called

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Teaching with Inspiration,

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Not Only Fear.

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How can astronomers

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provide students and the public with a positive

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pathway

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to addressing climate change

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and building

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a better future. I think you you hinted

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at one way,

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just a minute ago. Yeah. So I think

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this is incredibly important for us to understand,

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especially with our our students who are younger,

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and that is there is a lot of

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fear.

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It's called climate doomism. It's the the sense

281
00:10:55,149 --> 00:10:57,389
that it's too late, that nothing can be

282
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done.

283
00:10:58,555 --> 00:11:00,634
And what's important I mean, I have students

284
00:11:00,634 --> 00:11:02,715
telling me that they aren't going to have

285
00:11:02,715 --> 00:11:05,595
kids because they don't wanna bring children into

286
00:11:05,595 --> 00:11:06,815
a a ruined world.

287
00:11:07,274 --> 00:11:09,595
And there is a recent study that found

288
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that 75%

289
00:11:11,220 --> 00:11:13,459
of people under the age of 25 are

290
00:11:13,459 --> 00:11:15,379
terrified of their futures. They're scared of their

291
00:11:15,379 --> 00:11:15,879
future.

292
00:11:16,339 --> 00:11:18,259
So one of the most important things that

293
00:11:18,259 --> 00:11:20,419
we can do for our students is to

294
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help them see that we can actually create

295
00:11:22,500 --> 00:11:23,159
a world

296
00:11:23,764 --> 00:11:25,684
that is gonna be good to live in.

297
00:11:25,684 --> 00:11:27,205
And one of the things that I really

298
00:11:27,205 --> 00:11:30,404
like about, Jeff Bennett's chapter is he talks

299
00:11:30,404 --> 00:11:30,904
about

300
00:11:31,365 --> 00:11:34,004
helping students understand what our world can look

301
00:11:34,004 --> 00:11:36,565
like after we solve the problem of climate

302
00:11:36,565 --> 00:11:38,725
change. So often, we don't even talk about

303
00:11:38,725 --> 00:11:39,225
what

304
00:11:39,659 --> 00:11:40,399
that could

305
00:11:40,700 --> 00:11:43,339
be. And, yes, climate change is serious. It

306
00:11:43,339 --> 00:11:46,059
is a terrible problem. Every day in the

307
00:11:46,059 --> 00:11:49,440
news, we're seeing stories about firestorms and flooding

308
00:11:49,740 --> 00:11:52,639
and people's lives being affected or destroyed.

309
00:11:53,125 --> 00:11:55,684
And we're not trying to sugarcoat the reality

310
00:11:55,684 --> 00:11:56,504
of the problem,

311
00:11:56,884 --> 00:11:58,404
but we do know that there is a

312
00:11:58,404 --> 00:12:01,144
path forward. We have nearly all the solutions

313
00:12:01,205 --> 00:12:03,225
we need to address climate change,

314
00:12:03,605 --> 00:12:05,925
but the biggest issue here is getting people

315
00:12:05,925 --> 00:12:06,425
motivated

316
00:12:06,920 --> 00:12:09,180
to actually want to work towards a future

317
00:12:09,639 --> 00:12:12,059
that they could be excited to live in.

318
00:12:12,759 --> 00:12:14,680
And you you mentioned that some of your

319
00:12:14,680 --> 00:12:17,259
students are, perhaps rightly so,

320
00:12:18,759 --> 00:12:21,674
have neg sort sort of negative thoughts about

321
00:12:21,674 --> 00:12:24,475
the the implications of climate change. But I

322
00:12:24,475 --> 00:12:26,634
mean, do you also find that that the

323
00:12:26,634 --> 00:12:29,215
people you teach, there's some positiveness

324
00:12:29,595 --> 00:12:32,154
in there that that people think, yes, this

325
00:12:32,154 --> 00:12:34,394
is something that that we can we can

326
00:12:34,394 --> 00:12:36,779
fix, we can address this, and if I

327
00:12:36,940 --> 00:12:39,759
if I study astronomy, if I study science,

328
00:12:39,899 --> 00:12:43,519
I can make a a major contribution to

329
00:12:43,820 --> 00:12:47,279
solving the problem. Well, I'll say every semester

330
00:12:47,420 --> 00:12:49,660
I'm really impressed with the students that I

331
00:12:49,660 --> 00:12:51,840
have. And so many of them are already

332
00:12:52,394 --> 00:12:55,615
motivated and involved in working towards solutions.

333
00:12:56,074 --> 00:12:58,894
And it doesn't have to be big solutions.

334
00:12:58,954 --> 00:13:02,174
It can be community level solutions working,

335
00:13:02,954 --> 00:13:05,995
within your neighborhood, working within your school or

336
00:13:05,995 --> 00:13:06,735
your classes.

337
00:13:07,279 --> 00:13:08,980
So many kids now understand

338
00:13:09,519 --> 00:13:11,279
the problems of the world in ways that

339
00:13:11,279 --> 00:13:12,259
I feel like that

340
00:13:12,720 --> 00:13:15,779
my generation did not. Our our students

341
00:13:16,240 --> 00:13:18,740
have access to social media and provides

342
00:13:19,360 --> 00:13:21,519
information to them in a way that,

343
00:13:23,125 --> 00:13:26,345
I don't think earlier generations had. I'm continually

344
00:13:26,404 --> 00:13:28,565
impressed with my daughter and her awareness of

345
00:13:28,565 --> 00:13:30,565
of the issues in the world. So this

346
00:13:30,565 --> 00:13:33,445
is a generation that unfortunately is inheriting a

347
00:13:33,445 --> 00:13:35,784
problem that was created by prior generations,

348
00:13:36,460 --> 00:13:38,799
but I'm also very impressed with how motivated

349
00:13:38,940 --> 00:13:41,179
many of them are to address it. And

350
00:13:41,179 --> 00:13:41,679
so

351
00:13:42,220 --> 00:13:44,940
one of the things that scientists often focus

352
00:13:44,940 --> 00:13:47,500
on is trying to convince people that climate

353
00:13:47,500 --> 00:13:49,674
change is happening. And I think what's more

354
00:13:49,674 --> 00:13:52,475
important now is convincing people that we can

355
00:13:52,475 --> 00:13:54,714
address the problem and that they can have

356
00:13:54,714 --> 00:13:55,214
a

357
00:13:55,514 --> 00:13:57,394
role in fixing it. And so so many

358
00:13:57,394 --> 00:13:59,595
of my students, the first question really is,

359
00:13:59,595 --> 00:14:01,355
well, what can I do? How can I

360
00:14:01,355 --> 00:14:02,894
be involved? And so

361
00:14:03,549 --> 00:14:06,129
giving students resources and information,

362
00:14:06,429 --> 00:14:09,309
like, for example, project drawdown is a wonderful

363
00:14:09,309 --> 00:14:09,809
resource

364
00:14:10,269 --> 00:14:12,429
that helps people see all the solutions out

365
00:14:12,429 --> 00:14:14,750
there. It gives them an opportunity to find

366
00:14:14,750 --> 00:14:16,944
the place where they are gonna be most

367
00:14:16,944 --> 00:14:18,004
interested in working.

368
00:14:19,024 --> 00:14:21,605
I see. Well, that that sounds very positive.

369
00:14:21,904 --> 00:14:22,884
And, Travis,

370
00:14:23,504 --> 00:14:25,584
if I can, I'd I'd like to ask

371
00:14:25,584 --> 00:14:26,324
you maybe

372
00:14:27,600 --> 00:14:30,320
something on a more personal level. I mentioned

373
00:14:30,320 --> 00:14:32,259
in the introduction that you've noticed

374
00:14:32,720 --> 00:14:35,379
changes in in your native Alaska

375
00:14:36,079 --> 00:14:38,019
that that have concerned you.

376
00:14:38,399 --> 00:14:40,264
Is it possible for you to to give

377
00:14:40,264 --> 00:14:42,398
us a a few examples of things that

378
00:14:42,398 --> 00:14:43,164
are changing,

379
00:14:43,945 --> 00:14:46,845
because of because of global warming climate change?

380
00:14:47,544 --> 00:14:50,024
Yeah. So I've been in Alaska for over

381
00:14:50,024 --> 00:14:51,725
20 years now, and

382
00:14:52,184 --> 00:14:54,345
in that time, we've seen quite a bit

383
00:14:54,345 --> 00:14:55,725
of change. The Arctic

384
00:14:56,159 --> 00:14:58,480
in general is warming at about 3 times

385
00:14:58,480 --> 00:15:00,159
the rate as the rest of the world

386
00:15:00,159 --> 00:15:02,799
due to the ice albedo feedback loop with

387
00:15:02,799 --> 00:15:04,419
the with the Arctic sea.

388
00:15:05,519 --> 00:15:08,159
I've seen glaciers recede to the point now

389
00:15:08,159 --> 00:15:08,659
where

390
00:15:09,535 --> 00:15:11,295
I have pictures of myself when I first

391
00:15:11,295 --> 00:15:12,735
got here that if I was standing in

392
00:15:12,735 --> 00:15:14,575
that same location and took a picture, you

393
00:15:14,575 --> 00:15:16,175
would not be able to see the glacier.

394
00:15:16,175 --> 00:15:18,975
In fact, there's a glacier near Anchorage called

395
00:15:18,975 --> 00:15:19,875
Portage Glacier

396
00:15:20,254 --> 00:15:22,254
that they built a visitor center for you

397
00:15:22,254 --> 00:15:23,870
to look at it, and you can't see

398
00:15:23,870 --> 00:15:26,190
the glacier from there anymore. It's receded so

399
00:15:26,190 --> 00:15:26,690
much.

400
00:15:27,149 --> 00:15:27,970
There's also,

401
00:15:28,350 --> 00:15:32,110
dire effects for, seafood. When off when often

402
00:15:32,110 --> 00:15:34,190
we think about climate change, we think about

403
00:15:34,190 --> 00:15:36,110
global warming. We think about how the earth

404
00:15:36,110 --> 00:15:37,009
is getting warmer.

405
00:15:37,625 --> 00:15:40,745
But another side effect of climate change is

406
00:15:40,745 --> 00:15:41,644
ocean acidification.

407
00:15:42,184 --> 00:15:44,445
The carbon dioxide releasing the atmosphere,

408
00:15:44,904 --> 00:15:46,904
about a quarter of that is being absorbed

409
00:15:46,904 --> 00:15:47,964
by the earth's oceans,

410
00:15:48,345 --> 00:15:50,904
and that is creating carbonic acid and making

411
00:15:50,904 --> 00:15:52,125
the oceans more acidic.

412
00:15:52,700 --> 00:15:55,179
The fishing industry is the largest employer in

413
00:15:55,179 --> 00:15:58,559
the state of Alaska, and, species like salmon

414
00:15:58,620 --> 00:16:01,100
and king crabs and Tanner crabs are not

415
00:16:01,100 --> 00:16:03,100
only a major part of our economy, but

416
00:16:03,100 --> 00:16:05,259
also part of our our culture and our

417
00:16:05,259 --> 00:16:05,759
identity.

418
00:16:06,379 --> 00:16:07,120
And so

419
00:16:07,774 --> 00:16:10,095
in recent years, we've had the collapse of

420
00:16:10,095 --> 00:16:13,215
several fisheries due to warmer waters and ocean

421
00:16:13,215 --> 00:16:13,715
acidification.

422
00:16:14,815 --> 00:16:17,055
And that's the part that's hardest for me

423
00:16:17,055 --> 00:16:18,675
to see, is to see how

424
00:16:19,055 --> 00:16:21,830
our lives and traditions here in Alaska are

425
00:16:21,830 --> 00:16:23,990
being affected by climate change. And it really

426
00:16:23,990 --> 00:16:26,629
is a major driver for the advocacy work

427
00:16:26,629 --> 00:16:27,450
that I do.

428
00:16:28,470 --> 00:16:30,470
Yeah. It is it is interesting. I mean,

429
00:16:30,470 --> 00:16:32,070
you know, from my point of view, I'm

430
00:16:32,070 --> 00:16:34,470
I'm from Canada originally, but I I've lived

431
00:16:34,470 --> 00:16:37,024
in the UK for for many, many years.

432
00:16:37,725 --> 00:16:39,504
And the the thing that,

433
00:16:39,965 --> 00:16:41,404
you know, I've I've I sort of had

434
00:16:41,404 --> 00:16:42,225
this emotional

435
00:16:42,924 --> 00:16:45,105
tie to to the concept of winter.

436
00:16:45,884 --> 00:16:47,644
And and it seems to me that, you

437
00:16:47,644 --> 00:16:49,485
know, if if whenever I get back to

438
00:16:49,485 --> 00:16:50,784
Canada in the winter,

439
00:16:51,289 --> 00:16:52,990
there seems to be less of it.

440
00:16:54,009 --> 00:16:54,169
And,

441
00:16:54,889 --> 00:16:55,949
you know, there there's

442
00:16:56,329 --> 00:16:57,629
culture and tradition,

443
00:16:58,730 --> 00:17:01,149
where I come from, you know, things like

444
00:17:01,529 --> 00:17:04,329
ice fishing or skating on a on a

445
00:17:04,329 --> 00:17:05,265
frozen lake,

446
00:17:06,144 --> 00:17:08,005
things that I really enjoyed doing

447
00:17:08,305 --> 00:17:10,085
when I was a child. And

448
00:17:10,625 --> 00:17:12,164
I realize now that,

449
00:17:13,025 --> 00:17:14,464
well, the last time I was there, you

450
00:17:14,464 --> 00:17:16,404
just couldn't do it. There was no ice

451
00:17:16,945 --> 00:17:19,424
on the lakes, which was a big shock

452
00:17:19,424 --> 00:17:20,085
to me.

453
00:17:20,539 --> 00:17:23,500
And I suppose I struggle to, to to

454
00:17:23,500 --> 00:17:24,859
not be sad about it.

455
00:17:25,419 --> 00:17:27,019
But it's great to, you know, to hear

456
00:17:27,019 --> 00:17:29,200
that astronomers like yourselves are

457
00:17:29,579 --> 00:17:31,740
are clubbing together to to try to make

458
00:17:31,740 --> 00:17:34,299
a difference, and also that that the young

459
00:17:34,299 --> 00:17:36,000
people that you teach are

460
00:17:36,355 --> 00:17:39,154
are positive that they want to do something

461
00:17:39,154 --> 00:17:41,575
about it. That's that's really nice to hear.

462
00:17:42,034 --> 00:17:44,115
Yeah. It's a it's a it's a mix

463
00:17:44,115 --> 00:17:46,534
of of sadness and optimism.

464
00:17:47,154 --> 00:17:49,075
As I've heard said before, hope is a

465
00:17:49,075 --> 00:17:49,559
choice.

466
00:17:50,200 --> 00:17:52,860
And I think it's important for us to

467
00:17:53,240 --> 00:17:53,740
acknowledge

468
00:17:54,200 --> 00:17:56,700
the the sadness that we feel. I I

469
00:17:57,000 --> 00:17:59,720
like you, I love winter. It's my favorite

470
00:17:59,720 --> 00:18:01,799
time of year. I love snow. I love

471
00:18:01,799 --> 00:18:02,539
ice skating.

472
00:18:03,240 --> 00:18:06,325
And it's been hard to watch how Alaska

473
00:18:06,325 --> 00:18:07,924
has changed in that way. Our winters are

474
00:18:07,924 --> 00:18:08,424
shorter.

475
00:18:08,805 --> 00:18:09,545
We're getting

476
00:18:10,085 --> 00:18:11,684
we get good snow, but we also are

477
00:18:11,684 --> 00:18:12,744
getting more rain.

478
00:18:13,285 --> 00:18:13,785
And

479
00:18:14,244 --> 00:18:16,565
I think every community in the world now

480
00:18:16,565 --> 00:18:19,230
is feeling the effects of climate change. Most

481
00:18:19,230 --> 00:18:20,690
everyone I talk with nowadays

482
00:18:21,390 --> 00:18:22,130
can identify

483
00:18:22,430 --> 00:18:23,089
an event

484
00:18:23,630 --> 00:18:26,450
that has happened that was climate change enhanced,

485
00:18:26,509 --> 00:18:28,130
whether, again, be a firestorm

486
00:18:28,430 --> 00:18:29,329
or flooding.

487
00:18:29,789 --> 00:18:32,269
So people understand things are different now, and

488
00:18:32,269 --> 00:18:35,944
there's sadness associated with thinking that our our

489
00:18:35,944 --> 00:18:37,484
lives and our world has changed.

490
00:18:38,025 --> 00:18:38,525
But

491
00:18:38,984 --> 00:18:40,744
the goal here, I think, is to help

492
00:18:40,744 --> 00:18:43,005
people see that we can still avoid

493
00:18:43,464 --> 00:18:44,605
the worst consequences.

494
00:18:44,984 --> 00:18:45,484
And,

495
00:18:46,769 --> 00:18:48,150
I've heard it quite recently

496
00:18:48,690 --> 00:18:51,089
that if you're not optimistic, you're not paying

497
00:18:51,089 --> 00:18:53,250
attention. There's a lot of good news out

498
00:18:53,250 --> 00:18:54,470
there right now about

499
00:18:54,849 --> 00:18:56,769
the solutions that are out there, and and

500
00:18:56,769 --> 00:18:58,785
they're taking effect. I mean, wind and solar

501
00:18:59,345 --> 00:19:01,924
has grown much faster than anyone,

502
00:19:02,305 --> 00:19:05,505
dared anticipate 10 years ago. So there's lots

503
00:19:05,505 --> 00:19:07,184
to be sad about, but there's also a

504
00:19:07,184 --> 00:19:08,005
lot to be

505
00:19:08,305 --> 00:19:09,285
excited about.

506
00:19:09,664 --> 00:19:11,664
Well, that's great, Travis. That's a great place

507
00:19:11,664 --> 00:19:14,330
to, to to leave it. Thanks so much

508
00:19:14,330 --> 00:19:17,529
for speaking to me today. And listeners, you

509
00:19:17,529 --> 00:19:19,950
can find climate change for astronomers

510
00:19:20,410 --> 00:19:21,470
on the IOPscience

511
00:19:22,090 --> 00:19:22,590
website.

512
00:19:30,375 --> 00:19:33,194
The central thesis of climate change is simple.

513
00:19:33,575 --> 00:19:34,234
A relentless

514
00:19:34,694 --> 00:19:37,515
increase in carbon dioxide in the atmosphere

515
00:19:38,055 --> 00:19:41,119
is reducing the amount of heat that earth

516
00:19:41,180 --> 00:19:42,720
radiates into space,

517
00:19:43,180 --> 00:19:45,279
and that's warming the planet.

518
00:19:45,980 --> 00:19:49,519
There are, however, myriad other factors that affect

519
00:19:49,579 --> 00:19:51,440
how the climate is changing,

520
00:19:52,059 --> 00:19:55,420
including the role that clouds play in both

521
00:19:55,420 --> 00:19:55,920
heating

522
00:19:56,515 --> 00:19:57,894
and cooling the planet.

523
00:19:58,674 --> 00:20:01,714
To talk about clouds and climate, I'm joined

524
00:20:01,714 --> 00:20:03,974
down the line by the science writer,

525
00:20:04,275 --> 00:20:05,335
Michael Allen,

526
00:20:05,795 --> 00:20:08,454
who has penned the Physics World article,

527
00:20:09,139 --> 00:20:11,240
cloudy with a chance of warming,

528
00:20:11,700 --> 00:20:12,519
how physicists

529
00:20:12,819 --> 00:20:13,639
are studying

530
00:20:13,940 --> 00:20:14,759
the dynamical

531
00:20:15,220 --> 00:20:16,679
impact of clouds

532
00:20:16,980 --> 00:20:18,279
on climate change.

533
00:20:18,819 --> 00:20:19,639
Hi, Michael.

534
00:20:20,019 --> 00:20:21,240
Welcome to the podcast.

535
00:20:22,035 --> 00:20:24,835
Hi, Hamish. Nice to be here. So, Michael,

536
00:20:24,835 --> 00:20:26,855
can you give us a a a basic

537
00:20:26,914 --> 00:20:27,414
idea

538
00:20:27,875 --> 00:20:30,835
of how clouds affect climate? I mean, we

539
00:20:30,835 --> 00:20:32,695
all know that when we're outside

540
00:20:33,394 --> 00:20:33,875
and,

541
00:20:34,195 --> 00:20:36,914
a cloud comes over, covers the sun, it

542
00:20:36,914 --> 00:20:37,815
cools down.

543
00:20:38,250 --> 00:20:40,589
Many of us are also aware that

544
00:20:40,970 --> 00:20:41,630
at night

545
00:20:42,089 --> 00:20:45,210
cloud cover can can sort of increase the

546
00:20:45,210 --> 00:20:45,710
temperature

547
00:20:46,089 --> 00:20:48,910
that we experience once the sun goes down.

548
00:20:49,049 --> 00:20:51,130
But I'm guessing that there's lots of ways

549
00:20:51,130 --> 00:20:53,070
that, clouds can impact

550
00:20:53,455 --> 00:20:54,195
the climate.

551
00:20:55,055 --> 00:20:59,075
Yes. But the basic issue is quite simple,

552
00:20:59,295 --> 00:20:59,795
really.

553
00:21:00,975 --> 00:21:01,475
Clouds

554
00:21:01,934 --> 00:21:04,595
essentially play a role in the Earth's radiation

555
00:21:04,734 --> 00:21:07,309
budget, so that's the balance between the amount

556
00:21:07,309 --> 00:21:09,570
of energy that comes in from the sun

557
00:21:09,630 --> 00:21:11,549
and the amount of energy that kind of

558
00:21:11,549 --> 00:21:14,049
is reflected out to space as thermal

559
00:21:14,589 --> 00:21:15,089
energy

560
00:21:15,390 --> 00:21:16,369
from the Earth.

561
00:21:16,910 --> 00:21:17,650
And, essentially,

562
00:21:17,950 --> 00:21:21,250
clouds play 2 simple roles in this. 1

563
00:21:21,424 --> 00:21:23,845
is they reflect some clouds are reflective,

564
00:21:24,544 --> 00:21:27,265
so they reflect the sun's energy back into

565
00:21:27,265 --> 00:21:27,765
space,

566
00:21:28,224 --> 00:21:29,204
cooling the earth.

567
00:21:29,585 --> 00:21:31,444
And then then some clouds

568
00:21:31,825 --> 00:21:33,284
act a bit more like a blanket.

569
00:21:33,630 --> 00:21:36,190
They absorb that thermal energy that's radiators from

570
00:21:36,190 --> 00:21:38,190
the earth, and then they radiate it back

571
00:21:38,190 --> 00:21:39,329
towards the earth.

572
00:21:39,869 --> 00:21:43,070
And the balance between this, you know, the

573
00:21:43,070 --> 00:21:44,829
cooling of the clouds and the warming of

574
00:21:44,829 --> 00:21:45,404
the clouds

575
00:21:45,805 --> 00:21:46,305
impacts

576
00:21:47,085 --> 00:21:49,505
how much heat reaches the Earth's surface.

577
00:21:50,045 --> 00:21:51,805
But as you pointed out, we can see

578
00:21:51,805 --> 00:21:53,984
clouds when we look up, and

579
00:21:54,845 --> 00:21:57,585
there are lots of clouds around. And researchers

580
00:21:57,644 --> 00:22:00,045
tell me that the basic problem is that

581
00:22:00,045 --> 00:22:01,289
a small shift

582
00:22:02,650 --> 00:22:03,789
in cloud amounts

583
00:22:04,250 --> 00:22:06,430
between these different clouds that are reflective

584
00:22:06,970 --> 00:22:09,369
or acting like a blanket can have quite

585
00:22:09,369 --> 00:22:10,670
a significant impact

586
00:22:11,450 --> 00:22:13,230
on the Earth's radiation budget.

587
00:22:13,625 --> 00:22:16,505
And, basically, climate change plays into this because

588
00:22:16,505 --> 00:22:17,164
it affects

589
00:22:17,705 --> 00:22:19,965
how clouds kind of form and develop.

590
00:22:21,065 --> 00:22:22,125
I see. And

591
00:22:22,664 --> 00:22:24,605
I suppose that there's lots of different

592
00:22:24,985 --> 00:22:26,045
types of clouds.

593
00:22:26,505 --> 00:22:29,059
I'm going to show my ignorance here by

594
00:22:29,059 --> 00:22:32,680
referring to high level clouds and low clouds.

595
00:22:33,140 --> 00:22:35,480
I'm sure that there's much more technical terms,

596
00:22:36,019 --> 00:22:39,640
available. But those clouds at at different

597
00:22:39,940 --> 00:22:40,440
altitudes

598
00:22:40,820 --> 00:22:44,285
play very different roles, don't they, in in

599
00:22:44,285 --> 00:22:45,184
Earth's temperature?

600
00:22:46,845 --> 00:22:49,025
Yes. I mean, I'm also fairly ignorant

601
00:22:49,404 --> 00:22:51,825
on the different types of clouds too. But

602
00:22:51,964 --> 00:22:53,644
I think, again, as you point out, on

603
00:22:53,644 --> 00:22:55,424
a relatively simple level,

604
00:22:56,170 --> 00:22:59,130
low altitude clouds, so the clouds that sit

605
00:22:59,130 --> 00:23:00,269
in the troposphere,

606
00:23:00,650 --> 00:23:02,029
the kind of lowest

607
00:23:02,410 --> 00:23:03,869
level of the Earth's atmosphere

608
00:23:04,970 --> 00:23:08,250
are generally reflective, so they are reflecting sunlight

609
00:23:08,250 --> 00:23:10,085
back out to space, while

610
00:23:11,105 --> 00:23:14,384
the higher altitude clouds, which again sit in

611
00:23:14,384 --> 00:23:16,724
the same part of the atmosphere, the troposphere,

612
00:23:16,784 --> 00:23:19,105
but right at the top of it tend

613
00:23:19,105 --> 00:23:21,765
to have more of this blanket warming effect.

614
00:23:22,650 --> 00:23:25,630
I see. And and so how are rising

615
00:23:25,769 --> 00:23:26,830
global temperatures

616
00:23:27,210 --> 00:23:27,710
affecting

617
00:23:28,330 --> 00:23:30,029
cloud cover and formation?

618
00:23:31,130 --> 00:23:33,710
Sure. So when it comes to these

619
00:23:34,090 --> 00:23:34,990
higher clouds,

620
00:23:36,055 --> 00:23:38,295
on a simple level, the heat into the

621
00:23:38,295 --> 00:23:41,275
atmosphere is causing the troposphere to expand

622
00:23:41,735 --> 00:23:44,375
and basically to rise higher. So that's this

623
00:23:44,375 --> 00:23:45,595
lower part of the atmosphere

624
00:23:46,134 --> 00:23:48,630
is rising to a higher altitude. So this

625
00:23:48,630 --> 00:23:52,150
means that those higher level clouds themselves can

626
00:23:52,150 --> 00:23:52,650
also

627
00:23:53,589 --> 00:23:54,490
rise higher.

628
00:23:55,670 --> 00:23:56,410
And then

629
00:23:57,109 --> 00:23:57,609
issues

630
00:23:58,230 --> 00:23:59,930
with rising temperatures

631
00:24:01,335 --> 00:24:03,015
and the effect of them on, like, the

632
00:24:03,015 --> 00:24:04,474
stability of the atmosphere

633
00:24:05,414 --> 00:24:07,994
is affected the kind of formation of clouds

634
00:24:08,375 --> 00:24:09,355
and how

635
00:24:09,815 --> 00:24:12,295
clouds in the lower atmosphere, particularly these lower

636
00:24:12,295 --> 00:24:15,740
level clouds that reflect sunlight back. Basically, kind

637
00:24:15,740 --> 00:24:16,880
of how they form

638
00:24:17,180 --> 00:24:19,019
and the kind of cloud fraction. That is

639
00:24:19,019 --> 00:24:21,200
the amount of kind of cloud in space.

640
00:24:21,740 --> 00:24:23,660
I see. And so so does that mean

641
00:24:23,660 --> 00:24:24,960
that in general,

642
00:24:25,595 --> 00:24:26,095
we're

643
00:24:26,795 --> 00:24:27,455
we're experiencing,

644
00:24:28,795 --> 00:24:30,894
less lower cloud cover

645
00:24:31,275 --> 00:24:33,855
and more higher cloud cover,

646
00:24:34,234 --> 00:24:35,615
which in itself

647
00:24:36,075 --> 00:24:36,575
is

648
00:24:36,955 --> 00:24:37,455
increasing

649
00:24:37,914 --> 00:24:38,654
the temperature

650
00:24:39,279 --> 00:24:41,759
of the planet? Or, I'm I'm I'm guessing

651
00:24:41,759 --> 00:24:43,839
it's not quite that simple. But is that

652
00:24:43,839 --> 00:24:45,779
sort of a a general trend

653
00:24:46,160 --> 00:24:46,660
that,

654
00:24:47,599 --> 00:24:49,380
climate scientists are seeing?

655
00:24:50,559 --> 00:24:53,674
So I think the evidence on low clouds

656
00:24:53,674 --> 00:24:54,894
is reasonably

657
00:24:55,194 --> 00:24:55,694
clear

658
00:24:56,234 --> 00:24:56,734
that

659
00:24:57,514 --> 00:24:59,294
rising temperatures are reducing

660
00:25:00,315 --> 00:25:03,034
the amount of low cloud cover, particularly over

661
00:25:03,034 --> 00:25:04,815
kind of tropic and subtropical

662
00:25:05,115 --> 00:25:07,670
regions. When it becomes to the higher level

663
00:25:07,670 --> 00:25:08,170
clouds,

664
00:25:08,710 --> 00:25:11,670
I think that the science is a little

665
00:25:11,670 --> 00:25:13,930
less clear at the moment. So these clouds

666
00:25:14,950 --> 00:25:15,609
are rising,

667
00:25:16,630 --> 00:25:19,049
and the assumption is that that also

668
00:25:19,350 --> 00:25:19,850
increases

669
00:25:20,230 --> 00:25:21,289
this kind of blanket

670
00:25:21,724 --> 00:25:22,625
blanketing effect,

671
00:25:23,005 --> 00:25:23,505
but

672
00:25:23,884 --> 00:25:26,285
it's not really clear, I don't think yet,

673
00:25:26,285 --> 00:25:28,605
exactly what else is happening to these clouds

674
00:25:28,605 --> 00:25:29,585
as they rise.

675
00:25:29,884 --> 00:25:32,464
So there could be other changes in them

676
00:25:32,684 --> 00:25:33,744
that also

677
00:25:34,529 --> 00:25:35,029
impact

678
00:25:35,650 --> 00:25:37,910
their impact on the Earth's radiation budget.

679
00:25:38,369 --> 00:25:40,210
Right. And I I think in your article,

680
00:25:40,210 --> 00:25:41,190
you do mention

681
00:25:41,570 --> 00:25:44,210
things like, you know, what percentage of a

682
00:25:44,210 --> 00:25:44,710
cloud,

683
00:25:46,529 --> 00:25:48,470
is made up of liquid droplets,

684
00:25:48,775 --> 00:25:51,335
and how much is ice, and how that

685
00:25:51,335 --> 00:25:53,275
is changing, and how that affects,

686
00:25:54,214 --> 00:25:56,134
climate. So it is it is a very

687
00:25:56,134 --> 00:25:57,994
complicated system, isn't it?

688
00:25:58,535 --> 00:26:00,295
So, yeah, now we are getting into what

689
00:26:00,295 --> 00:26:02,759
are known as mixed flay phase clouds, which

690
00:26:03,000 --> 00:26:05,559
exist in the northern and southern hemisphere, kind

691
00:26:05,559 --> 00:26:08,039
of outside of the tropical regions. And these

692
00:26:08,039 --> 00:26:09,660
are clouds that are a mixture

693
00:26:10,039 --> 00:26:11,180
of liquids,

694
00:26:12,119 --> 00:26:12,619
water,

695
00:26:13,160 --> 00:26:13,980
and ice.

696
00:26:15,160 --> 00:26:16,539
And the basic

697
00:26:17,515 --> 00:26:20,654
problem here is that as these clouds warm,

698
00:26:20,795 --> 00:26:22,335
they shift from being

699
00:26:23,595 --> 00:26:25,994
more ice to being more liquid, and thus

700
00:26:25,994 --> 00:26:27,775
they become more reflective.

701
00:26:28,394 --> 00:26:30,474
So they are bouncing more of the sun's

702
00:26:30,474 --> 00:26:32,039
energy back into space,

703
00:26:32,600 --> 00:26:35,240
and this has a dampening effect on climate

704
00:26:35,240 --> 00:26:35,740
change.

705
00:26:36,359 --> 00:26:39,480
But problems have arisen around how these clouds

706
00:26:39,480 --> 00:26:40,059
are modeled,

707
00:26:40,840 --> 00:26:41,900
so it appears

708
00:26:42,840 --> 00:26:45,005
well, research has shown that

709
00:26:45,944 --> 00:26:46,444
simulations

710
00:26:46,904 --> 00:26:49,305
have been modeling these clouds to to start

711
00:26:49,305 --> 00:26:50,204
off being

712
00:26:50,825 --> 00:26:53,384
having higher proportions of ice than they actually

713
00:26:53,384 --> 00:26:53,884
do.

714
00:26:54,424 --> 00:26:54,924
So

715
00:26:55,625 --> 00:26:57,625
that means that they can become

716
00:26:58,140 --> 00:27:00,299
there's a kind of bigger shift in their

717
00:27:00,299 --> 00:27:03,339
reflectiveness, and it's happening in reality. So that

718
00:27:03,339 --> 00:27:04,320
kind of affects

719
00:27:05,019 --> 00:27:06,559
how these climate models

720
00:27:07,579 --> 00:27:08,079
simulate

721
00:27:08,460 --> 00:27:10,960
the change in the radiation budget

722
00:27:11,259 --> 00:27:13,920
as these clouds move from ice to liquid.

723
00:27:14,275 --> 00:27:16,275
And one important part of this is that

724
00:27:16,275 --> 00:27:18,355
at some point, these clouds become kind of

725
00:27:18,355 --> 00:27:18,855
predominantly

726
00:27:19,714 --> 00:27:20,615
or entirely

727
00:27:20,994 --> 00:27:21,494
liquid.

728
00:27:21,954 --> 00:27:22,855
So that means

729
00:27:23,394 --> 00:27:25,654
they their their increasing reflectiveness

730
00:27:26,115 --> 00:27:26,615
stops.

731
00:27:27,289 --> 00:27:30,329
So whilst the earth is warming with climate

732
00:27:30,329 --> 00:27:30,829
change,

733
00:27:31,130 --> 00:27:32,970
to start with, the reflection this is this

734
00:27:33,049 --> 00:27:35,690
of these clouds is increasing, having a dampening

735
00:27:35,690 --> 00:27:37,230
effect, but then it slows,

736
00:27:37,849 --> 00:27:40,269
and then it stops increasing. So the reflectiveness

737
00:27:40,409 --> 00:27:41,585
is still there,

738
00:27:42,204 --> 00:27:44,845
but it remains at that level whilst the

739
00:27:44,845 --> 00:27:46,865
heat of the earth continues to

740
00:27:47,565 --> 00:27:49,664
increase. So you get a slowdown

741
00:27:50,924 --> 00:27:53,819
in this dampening effect that the clouds have.

742
00:27:53,899 --> 00:27:55,659
So, yeah, Michael. I mean, it sounds like

743
00:27:55,659 --> 00:27:56,960
it is a very complicated,

744
00:27:58,139 --> 00:27:59,919
relationship between clouds

745
00:28:00,299 --> 00:28:01,200
and climate.

746
00:28:01,819 --> 00:28:05,019
In your article, you also mention other sort

747
00:28:05,019 --> 00:28:07,440
of effects that humans

748
00:28:08,174 --> 00:28:10,914
are having on clouds, and and in particular,

749
00:28:11,214 --> 00:28:11,714
aerosols.

750
00:28:12,974 --> 00:28:15,134
It you you point out that,

751
00:28:15,774 --> 00:28:16,835
if we reduce,

752
00:28:17,534 --> 00:28:18,034
aerosol

753
00:28:18,335 --> 00:28:21,855
emissions, which is very important because aerosols can

754
00:28:21,855 --> 00:28:22,595
be lethal,

755
00:28:23,579 --> 00:28:24,539
in terms of,

756
00:28:25,019 --> 00:28:26,880
causing things like lung disease.

757
00:28:27,660 --> 00:28:30,400
That could actually lead to more

758
00:28:30,779 --> 00:28:31,279
warming.

759
00:28:31,819 --> 00:28:32,880
So why,

760
00:28:33,740 --> 00:28:35,440
our efforts to cut

761
00:28:35,740 --> 00:28:36,240
aerosol

762
00:28:36,700 --> 00:28:37,200
emissions,

763
00:28:38,755 --> 00:28:39,974
Why are they counterproductive

764
00:28:40,355 --> 00:28:41,815
when it comes to battling

765
00:28:42,195 --> 00:28:43,095
climate change?

766
00:28:43,954 --> 00:28:45,954
Yeah. Sure. I mean, you point to quite

767
00:28:45,954 --> 00:28:48,695
a dilemma here for kind of climate scientists.

768
00:28:49,315 --> 00:28:52,619
You know, we need to reduce aerosol pollutions

769
00:28:52,619 --> 00:28:53,980
because like you said, they have a huge

770
00:28:53,980 --> 00:28:55,359
health health impact.

771
00:28:55,980 --> 00:28:58,859
They're globally, something like 8,000,000 people die every

772
00:28:58,859 --> 00:29:00,000
year from air pollution.

773
00:29:01,099 --> 00:29:01,599
But,

774
00:29:02,380 --> 00:29:02,880
basically,

775
00:29:03,980 --> 00:29:05,359
when it comes to clouds,

776
00:29:06,455 --> 00:29:06,955
aerosols

777
00:29:07,654 --> 00:29:08,715
in the air pollution

778
00:29:10,215 --> 00:29:12,234
reduce the size of the cloud droplets,

779
00:29:12,535 --> 00:29:14,394
and this makes them more reflective.

780
00:29:15,095 --> 00:29:17,815
So they bounce again more of the sun's

781
00:29:17,815 --> 00:29:20,369
energy back out into space. So when we

782
00:29:20,369 --> 00:29:22,769
cut the amount of aerosols we're producing to

783
00:29:22,769 --> 00:29:24,630
tackle this dangerous air pollution,

784
00:29:25,570 --> 00:29:27,830
we make the clouds less reflective.

785
00:29:28,769 --> 00:29:31,170
So more of the sun's energy gets through

786
00:29:31,170 --> 00:29:32,390
and heats the earth.

787
00:29:33,015 --> 00:29:34,615
And so there you know, there's a bit

788
00:29:34,615 --> 00:29:35,994
of debate around this,

789
00:29:36,775 --> 00:29:39,414
but, you know, some people started to argue

790
00:29:39,414 --> 00:29:41,174
that actually if we were to cut all

791
00:29:41,174 --> 00:29:41,914
the aerosols

792
00:29:42,695 --> 00:29:43,994
and slash pollution,

793
00:29:44,455 --> 00:29:46,375
you know, in the way that some countries

794
00:29:46,375 --> 00:29:48,460
are trying to do, it could have a

795
00:29:48,460 --> 00:29:49,279
pretty significant

796
00:29:49,579 --> 00:29:51,900
impact on our chance of keeping global warming

797
00:29:51,900 --> 00:29:53,039
below 2 degrees.

798
00:29:53,339 --> 00:29:56,400
And other people I've spoken to suggested that,

799
00:29:56,539 --> 00:29:59,099
essentially, if we removed all aerosol pollution, we

800
00:29:59,099 --> 00:30:01,484
could create anywhere between an extra point 2

801
00:30:01,484 --> 00:30:03,904
to 0.6 degrees of additional warming.

802
00:30:04,365 --> 00:30:06,045
But, of course, we have to do it

803
00:30:06,045 --> 00:30:09,005
because we can't allow people just to be

804
00:30:09,005 --> 00:30:10,384
kind of dying from

805
00:30:10,845 --> 00:30:13,549
heart and lung disease because of pollution.

806
00:30:14,329 --> 00:30:16,329
Right. And I suppose the other thing is

807
00:30:16,329 --> 00:30:18,109
that some of that aerosol

808
00:30:18,649 --> 00:30:21,149
emission will will be related to

809
00:30:21,609 --> 00:30:22,429
carbon dioxide

810
00:30:22,970 --> 00:30:25,130
emission as well, won't it? So, you know,

811
00:30:25,130 --> 00:30:27,789
burning dirty fossil fuels, etcetera.

812
00:30:28,384 --> 00:30:31,264
So, I suppose in in some cases, you

813
00:30:31,264 --> 00:30:34,404
could you could reduce both aerosol emission

814
00:30:35,024 --> 00:30:37,764
and carbon dioxide emission at the same time.

815
00:30:37,984 --> 00:30:39,904
But I suppose that's you you have to

816
00:30:39,904 --> 00:30:42,784
be worried about the effect of reducing the

817
00:30:42,784 --> 00:30:43,284
aerosols.

818
00:30:44,880 --> 00:30:47,600
Yeah. Of course, these things are linked. They're

819
00:30:47,600 --> 00:30:48,900
they're not necessarily

820
00:30:49,200 --> 00:30:51,359
always the same sources, but they come but

821
00:30:51,359 --> 00:30:53,299
they do come from very similar

822
00:30:54,080 --> 00:30:56,500
industrial processes, fossil fuel

823
00:30:56,799 --> 00:30:57,700
burning processes.

824
00:30:58,085 --> 00:30:59,845
And I don't cover this in the article,

825
00:30:59,845 --> 00:31:02,164
but I think research has suggested that one

826
00:31:02,164 --> 00:31:03,684
of the best ways to deal with this

827
00:31:03,684 --> 00:31:05,224
really is just

828
00:31:05,845 --> 00:31:08,424
to slash both. So you are cutting the

829
00:31:08,724 --> 00:31:11,545
global warming element of the carbon dioxide emissions,

830
00:31:12,085 --> 00:31:12,585
and

831
00:31:13,230 --> 00:31:14,289
this kind of

832
00:31:15,390 --> 00:31:15,890
feedback

833
00:31:16,349 --> 00:31:17,250
from the aerosols.

834
00:31:18,509 --> 00:31:21,390
I see. And and I I suppose something

835
00:31:21,390 --> 00:31:23,009
that's related to aerosols

836
00:31:23,390 --> 00:31:23,869
is,

837
00:31:24,509 --> 00:31:26,130
the idea of cloud

838
00:31:26,509 --> 00:31:27,009
seeding.

839
00:31:28,055 --> 00:31:29,174
I suppose this is a

840
00:31:29,894 --> 00:31:31,755
is this called a a geoengineering

841
00:31:32,615 --> 00:31:35,914
technique where we we try to increase,

842
00:31:36,855 --> 00:31:39,734
the right kind of cloud cover in order

843
00:31:39,734 --> 00:31:40,234
to

844
00:31:40,694 --> 00:31:41,194
counteract

845
00:31:42,130 --> 00:31:42,630
climate

846
00:31:44,450 --> 00:31:46,069
change. Yes. So

847
00:31:47,410 --> 00:31:48,150
I guess

848
00:31:48,529 --> 00:31:49,910
the issue with the aerosols

849
00:31:50,289 --> 00:31:52,130
kind of opens up a question, which is

850
00:31:52,130 --> 00:31:52,630
basically,

851
00:31:53,009 --> 00:31:54,309
well, can we use

852
00:31:54,690 --> 00:31:56,470
aerosols that are perhaps nonpolluting

853
00:31:57,525 --> 00:32:00,005
to mitigate climate change? Can we make the

854
00:32:00,005 --> 00:32:01,625
clouds more reflective

855
00:32:02,724 --> 00:32:03,224
ourselves?

856
00:32:04,005 --> 00:32:06,404
And the idea behind this or the sort

857
00:32:06,404 --> 00:32:09,305
of idea that people proposed this is basically

858
00:32:09,605 --> 00:32:10,345
to use

859
00:32:11,045 --> 00:32:11,865
salt water

860
00:32:12,404 --> 00:32:12,904
spray

861
00:32:13,230 --> 00:32:15,549
as an aerosol. So I guess you would

862
00:32:15,549 --> 00:32:17,710
take a ship or something like that. You'd

863
00:32:17,710 --> 00:32:18,450
suck up

864
00:32:18,750 --> 00:32:19,250
seawater.

865
00:32:19,630 --> 00:32:21,650
You spray it out, and the idea

866
00:32:22,429 --> 00:32:24,910
is that this that this that the that

867
00:32:24,910 --> 00:32:26,049
it kind of evaporates

868
00:32:26,375 --> 00:32:27,994
and the fine haze of particles,

869
00:32:28,934 --> 00:32:30,535
the salt, and the other things in the

870
00:32:30,535 --> 00:32:31,035
seawater

871
00:32:31,975 --> 00:32:35,355
are transported into the clouds by air currents,

872
00:32:35,575 --> 00:32:36,555
and that reduces

873
00:32:37,015 --> 00:32:38,715
the droplet size in clouds

874
00:32:39,174 --> 00:32:39,914
and increases

875
00:32:40,215 --> 00:32:41,195
their brightness.

876
00:32:41,970 --> 00:32:43,890
I see. But I suppose the problem there

877
00:32:43,890 --> 00:32:46,769
is that if if country a is really

878
00:32:46,769 --> 00:32:47,269
suffering

879
00:32:48,289 --> 00:32:51,109
from climate change and decides to do this,

880
00:32:51,890 --> 00:32:54,450
aren't some of those clouds going to drift

881
00:32:54,450 --> 00:32:56,710
over, let's say, country b?

882
00:32:57,434 --> 00:32:57,755
And,

883
00:32:58,474 --> 00:33:00,714
you know, I suppose block out the sun

884
00:33:00,714 --> 00:33:01,694
and maybe affect

885
00:33:02,154 --> 00:33:03,214
its agriculture,

886
00:33:03,595 --> 00:33:06,234
or maybe country b is not suffering as

887
00:33:06,234 --> 00:33:08,875
much from from climate change. Maybe it's a

888
00:33:08,875 --> 00:33:12,029
bit further north or or something. There's aren't

889
00:33:12,029 --> 00:33:13,250
there huge geopolitical

890
00:33:13,710 --> 00:33:14,690
issues here

891
00:33:15,070 --> 00:33:17,470
when, when these sort of schemes are rolled

892
00:33:17,470 --> 00:33:19,950
out? Yes. I mean, obviously, we're moving beyond

893
00:33:19,950 --> 00:33:21,090
physics here and,

894
00:33:22,109 --> 00:33:23,650
there is something for

895
00:33:23,950 --> 00:33:24,450
politicians

896
00:33:24,830 --> 00:33:27,650
and society to discuss about how these

897
00:33:28,724 --> 00:33:31,305
technologies would be deployed. But exactly,

898
00:33:31,765 --> 00:33:32,505
you can't

899
00:33:33,365 --> 00:33:33,865
really

900
00:33:36,565 --> 00:33:37,625
just do this

901
00:33:37,924 --> 00:33:38,984
in one place.

902
00:33:39,845 --> 00:33:42,025
No. If you start if you just chose

903
00:33:42,679 --> 00:33:45,319
chose one location in the world to do

904
00:33:45,319 --> 00:33:47,319
this because you want to increase the reflection

905
00:33:47,319 --> 00:33:49,640
of the clouds there, that's gonna going to

906
00:33:49,640 --> 00:33:51,319
start to have kind of few, you know,

907
00:33:51,319 --> 00:33:53,799
it has the potential to have knock on

908
00:33:53,799 --> 00:33:54,940
effects to local

909
00:33:55,304 --> 00:33:57,224
circulation patterns and things if you're kind of

910
00:33:57,224 --> 00:33:58,984
cool in the air in that area. You

911
00:33:58,984 --> 00:34:01,484
know, it yeah. It it becomes really

912
00:34:01,865 --> 00:34:02,365
complicated.

913
00:34:02,984 --> 00:34:05,304
So a lot of research really is needed

914
00:34:05,304 --> 00:34:05,964
to model

915
00:34:06,585 --> 00:34:07,964
exactly how this

916
00:34:08,824 --> 00:34:09,964
such a technique

917
00:34:10,579 --> 00:34:12,679
would alter the clouds, but then

918
00:34:13,699 --> 00:34:15,880
going up to a much larger scale,

919
00:34:16,420 --> 00:34:18,579
how does that alter the clouds then affect

920
00:34:18,579 --> 00:34:19,719
the local climate

921
00:34:20,179 --> 00:34:23,380
and then a kind of larger, I guess,

922
00:34:23,380 --> 00:34:25,320
local climate and then the

923
00:34:25,699 --> 00:34:27,335
Earth's global climate.

924
00:34:28,034 --> 00:34:30,034
And then really, yes, I guess, as a

925
00:34:30,034 --> 00:34:31,494
society or societies,

926
00:34:31,795 --> 00:34:32,934
we need to decide

927
00:34:33,875 --> 00:34:35,715
whether or not we want to allow this

928
00:34:35,715 --> 00:34:37,795
technology to go ahead and how we manage

929
00:34:37,795 --> 00:34:39,175
it to ensure that

930
00:34:39,750 --> 00:34:42,230
everyone is getting the benefits from it rather

931
00:34:42,230 --> 00:34:43,929
than the situation like you suggest

932
00:34:44,309 --> 00:34:47,190
where some countries are doing this and benefiting

933
00:34:47,190 --> 00:34:47,690
themselves

934
00:34:48,070 --> 00:34:51,030
whilst having negative knock on effects for people

935
00:34:51,030 --> 00:34:51,530
elsewhere.

936
00:34:52,025 --> 00:34:54,664
Well, thanks for talking about clouds and climate

937
00:34:54,664 --> 00:34:56,925
change, Michael. It's, I mean, it's an it's

938
00:34:57,144 --> 00:34:57,724
an incredibly

939
00:34:58,105 --> 00:34:58,605
complicated,

940
00:34:59,704 --> 00:35:01,945
field of endeavor, and I'm sure there's lots

941
00:35:01,945 --> 00:35:05,550
of physicists and other researchers out there working

942
00:35:05,550 --> 00:35:07,570
very hard on improving

943
00:35:08,110 --> 00:35:10,430
our understanding of it. And if you'd like

944
00:35:10,430 --> 00:35:13,469
to, to read Michael's article, you can find

945
00:35:13,469 --> 00:35:15,570
it on the Physics World website.

946
00:35:16,030 --> 00:35:17,329
It's under the headline,

947
00:35:17,835 --> 00:35:21,295
cloudy with a chance of warming, how physicists

948
00:35:21,594 --> 00:35:22,335
are studying

949
00:35:22,635 --> 00:35:23,375
the dynamical

950
00:35:23,914 --> 00:35:25,135
impact of clouds

951
00:35:25,514 --> 00:35:27,994
on climate change. Thanks for coming on the

952
00:35:27,994 --> 00:35:30,655
podcast, Michael, and thanks for writing that article

953
00:35:30,715 --> 00:35:31,454
as well.

954
00:35:31,880 --> 00:35:33,559
No problem, Hamish. Thank you for talking to

955
00:35:33,559 --> 00:35:34,059
me.

956
00:35:41,160 --> 00:35:42,920
I'm afraid that's all the time we have

957
00:35:42,920 --> 00:35:44,219
for this week's podcast.

958
00:35:44,684 --> 00:35:48,125
Thanks to Travis Rechter and Michael Allen for

959
00:35:48,125 --> 00:35:49,184
joining me today.

960
00:35:49,485 --> 00:35:52,125
And a special thanks to our producer, Fred

961
00:35:52,125 --> 00:35:52,625
Ailes.

962
00:35:53,085 --> 00:35:55,565
We'll be back again next week when we'll

963
00:35:55,565 --> 00:35:58,144
be exploring the amazing properties

964
00:35:58,445 --> 00:35:59,344
of metamaterials.