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1:01

we appreciate when you follow us and share our

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show with your friends. Okay, here's

1:05

our show. You're listening

1:07

to shortwave from

1:10

NPR. About

1:12

10 years ago, science writer Ferris

1:14

Jaber came across a fact he

1:16

never heard before that blew his

1:18

mind. The Amazon rainforest does not simply

1:20

receive the rain for which it is so

1:22

famous, it actually generates about half of the

1:24

rain that falls on its canopy every year.

1:27

It may seem straightforward that trees and other

1:29

plants pull water from their soil, then release

1:31

what they don't need into the air. But

1:34

Ferris says it's not that simple. That

1:38

the process actually involves the entirety of

1:40

life within the forest. So

1:42

the Amazon is continually spewing these

1:44

invisible plumes of tiny biological particles.

1:47

Think pollen grains, fungal spores,

1:49

microbes, bits of leaves. They

1:52

get swept up into the atmosphere and

1:54

they become the particles on which water

1:56

vapor condenses in order to form clouds.

2:00

Because they're continually lofting all of this

2:02

water vapor and all these biological

2:04

particles into the atmosphere, they're dramatically

2:06

accelerating the water cycle. So

2:10

the more the rainforest is growing and thriving, the

2:12

more rain it is stimulating, and then the more

2:14

rain that is falling back to the forest, the

2:16

more it can grow. And the

2:18

more it can influence ecosystems elsewhere.

2:22

When Ferris learned that the Amazon forest

2:24

actually changes the rain cycle, not only

2:26

above its canopy, but on other continents,

2:28

it started to change the way he thought about life

2:31

on Earth. Because I'd always been

2:33

taught that life is subject to its

2:35

environment, not the other way around. And

2:37

here we're living things, changing

2:39

the weather on the scale of an entire

2:41

continent. So he started looking for

2:43

other examples of how life changes its surroundings,

2:46

which led him to write his new book,

2:48

Becoming Earth, How Our Planet Came

2:50

to Life. It explores the idea

2:53

that life doesn't just live on Earth,

2:55

life is Earth. The basic concept

2:57

of the world being alive is truly ancient.

2:59

We see that in religion and mythology going

3:01

way, way back. From the Aztecs,

3:03

the ancient Polynesians, and many other

3:06

indigenous cultures. But within Western

3:08

science, this idea that we can think of

3:10

Earth as a living entity has been very

3:12

controversial for a long time. Since

3:15

the 1960s, when James Lovelock and

3:17

then later, Lynn Margulis developed their

3:19

versions of the idea. That

3:21

was severely criticized and ridiculed by

3:23

many mainstream Western scientists, especially with

3:26

an evolutionary biology, because they did

3:28

not like this idea of Earth

3:30

being alive and being conflated with

3:32

an organism. But now, that's starting

3:34

to change with new research that's come out

3:36

in the last few decades. It

3:39

suggests that... Wherever life emerges,

3:42

it inevitably transforms its home

3:44

planet. And that together,

3:46

life and the greater planetary environment

3:49

do form a single, highly intricate

3:51

interconnected system. Today on the

3:53

show, what it means to consider Earth

3:55

a living planet. From bacteria-caused

3:58

rainfall to the delicate balance of the

4:00

Earth, we're going to talk of wildfires

4:02

and oxygen, we look at how the

4:04

environment shapes life and how life shapes

4:06

the environment. I'm Regina Barber

4:08

and you're listening to Shortwave, the

4:10

science podcast from NPR. Okay

4:20

first, let's dig into this idea of a living

4:23

earth. Like what does it mean and how

4:25

is it different from a planet with life on

4:27

it? Right, so one

4:29

of the biggest revelations for me when

4:31

writing this book is to stop thinking

4:33

of life as something that simply inhabits

4:35

the planet or resides on the planet's

4:37

surface and to think of life as

4:39

a literal physical extension of the planet.

4:45

A tree is a beautiful metaphor for

4:47

our living planet because by mass or

4:49

volume the majority of a tree is

4:52

actually dead tissue. It's dead wood that

4:54

is structural but contains no living cells

4:56

and there's just thin strips of living

4:59

tissue here and there ringed and laced

5:01

throughout that dead wood. Well earth is

5:03

similar in that you know the majority

5:05

of it is inanimate rock and water

5:08

and air but it has this beautiful

5:10

flowering skin of life that in some

5:12

ways sustains this larger living system. All

5:17

life forms are by definition systems. They

5:20

are networks of smaller components some of

5:22

which are animate and some of which

5:24

are inanimate and so in that regard

5:26

the earth is no different. It's just

5:28

that it is the largest of all

5:30

of those systems. It's all the other

5:32

ecosystems combined into the largest known living

5:34

system. So

5:37

what we call life emerged from

5:39

earth, it is made of earth

5:41

and then life loops back to

5:43

profoundly transform the larger planetary environment

5:46

and we can recognize that system

5:48

itself as the largest known living

5:50

entity because it demonstrates what seems

5:52

to be the most fundamental characteristic

5:54

of life at all scales which

5:56

is a capacity to regulate itself

5:59

to preserve itself. to endure. Somehow

6:01

we have to account

6:04

for Earth's incredible resiliency through time.

6:06

The fact that Earth has remained

6:08

alive for more than 4 billion

6:11

years is truly astonishing. Right,

6:13

and to illustrate kind of like how

6:15

this feedback is happening, you go through

6:17

a bunch of examples in your book.

6:19

One that really stuck out to me

6:21

is how bacteria can cause rain. Like,

6:23

how does this work? Yeah, I'm

6:26

fascinated by this capacity of

6:28

microbes to change the weather

6:31

and to stimulate rain and snow and

6:33

hail, in fact. So, you

6:35

know, there's microbes all over the surface

6:37

of the planet, both on land and

6:40

in the ocean, and they're continually swept

6:42

into the atmosphere by powerful winds, by

6:44

storm currents. And in addition

6:46

to the living microbes themselves, there's also all

6:48

kinds of, you know, bits and pieces of

6:51

life. Just biological confetti, you know, gets up

6:53

in the atmosphere and they become

6:55

seeds for both clouds and then

6:57

for ice crystals within the clouds.

6:59

And there's one microbe that's particularly

7:01

special, Pseudomonas syringae.

7:04

It has on its surface,

7:07

on its cell surface, proteins

7:09

that act as a template

7:11

to organize water molecules into

7:13

a solid ice crystal. And

7:15

it's the most effective so-called

7:17

ice nucleator that we've ever

7:19

discovered. It's so effective that

7:21

it's actually used worldwide on

7:23

ski slopes to create artificial

7:25

snow. So, yeah, we spray water into

7:27

the air with the proteins from these

7:30

microbes and they freeze the water, you

7:32

know, they help freeze the water and

7:34

turn it into snow. That's so

7:36

cool. Another cool example is how

7:38

life died the sky

7:40

blue. I love that imagery. Like, what did

7:42

the sky look like before it was blue?

7:45

Right. So if we go back

7:47

into Earth's ancient history, you know,

7:49

more than three billion years ago,

7:51

Earth probably had a hazy orange

7:54

sky. You know, it was probably

7:56

full of carbon dioxide and methane

7:58

and it had essentially no

8:00

free oxygen in it. And

8:03

so Saturn's largest moon, Titan, has

8:06

a sort of, yes, it has a

8:08

smoggy orange atmosphere that maybe resembles what

8:10

Earth's ancient atmosphere used to look like

8:12

for similar reasons. Cool. Okay,

8:14

but tell us why it's blue then. Right.

8:16

So when life started to

8:18

oxygenate the atmosphere, and this began maybe

8:21

two and a half billion years ago

8:23

with cyanobacteria, inventing

8:25

photosynthesis, you know, using sunlight and

8:27

water and then releasing oxygen as

8:29

a byproduct, and then later continued

8:32

with algae and land plants. So

8:34

this long process of oxygenating the

8:36

atmosphere completely revolutionized the chemistry of

8:38

the entire planet. And

8:41

in doing so shifted the color of the

8:43

sky towards the blue end of the spectrum.

8:47

So, you know, most times today when somebody

8:49

asks, why is the sky blue, the most

8:51

common answer you hear is, well, it's because

8:53

the atmosphere most effectively scatters the shortest wavelengths

8:56

of light. It's called Rayleigh

8:58

scattering. It's something I taught many,

9:00

many, many times. Well, there you go. You

9:02

probably know much more about it than I do. And

9:04

so, you know, my understanding is like that is why

9:06

when we look up the sky, we see blue because

9:08

it's those shortest wavelengths that are getting scattered. Yes. But

9:11

that depends entirely on the chemistry of the

9:13

atmosphere. If you have a different proportion, different

9:15

concentrations of different molecules in there, they're going

9:17

to scatter different wavelengths of light. And that

9:20

was the case back in Earth's ancient atmosphere

9:22

until life changed the picture. Let's

9:24

give the planetary scientists something too. It has also

9:26

a lot to do with volcanoes, but, you know.

9:29

Yes, that's true. My book

9:31

is kind of, you know, really focused on life. But

9:34

of course, geology is the second half of that picture.

9:36

It is always there as well. Right,

9:38

right. Okay. The next one that

9:41

we're going to talk about is this like

9:43

relation between like fire and life. So like

9:45

this coevolution of wildfire and plant life. I

9:47

can kind of see how these two are

9:49

connected, but can you like break it down

9:51

for me? Absolutely. So

9:54

for a long time in Earth's

9:56

history, the level of oxygen in

9:58

the atmosphere flushes. really

10:01

wildly. For example, if we go

10:03

back roughly 300 million years,

10:05

the level of atmospheric oxygen was somewhere between 30

10:07

to 35 percent compared to about 21 percent today.

10:09

And back then,

10:13

we had massive raging wildfires

10:15

unlike anything we've seen. And

10:17

so, something seemed to have shifted

10:19

about 200 million years ago, and especially in

10:22

the past 50 million years, where the level

10:24

of atmospheric oxygen is a lot more stable

10:26

than it used to be. It's hovering

10:28

around that 21 percent. And

10:31

so, scientists have long struggled to explain

10:33

that stability, and what they're converging on

10:35

now as a possible answer is the

10:38

co-evolution of fire at terrestrial plant life.

10:41

So, the basic idea is that if

10:44

oxygen levels get too high and

10:46

you have these raging wildfires, they're

10:48

going to burn down huge tracts

10:50

of terrestrial vegetation. So, when that

10:53

happens, oxygen levels start to

10:55

dip back down again, right? So, it's

10:57

the stabilizing feedback built into the system.

10:59

So, with all of these examples happening all at

11:01

the same time, what makes

11:04

Earth living? How do we

11:06

put all of these things in a conversation? What's the

11:08

sum of all of these? Right.

11:11

So, the way I think about

11:13

it is life is looping back

11:15

to change the planet really profoundly.

11:17

So, together, Earth and life are

11:19

forming this single system, this tightly

11:21

interconnected, tightly coupled system. And

11:24

this system as a whole demonstrates a

11:26

capacity to regulate itself, to

11:28

regulate the planet's climate, to

11:30

endure, to have resilience. These are the characteristics

11:34

that we associate with living things.

11:36

So, we can think of this

11:39

system as a whole as the largest

11:41

known living entity. Yeah, I'm

11:43

really intrigued by this idea

11:45

that Earth will balance its system out,

11:47

but like how the fire example took

11:49

millions of years, humans may not be

11:51

around for that balancing act, like to

11:53

see what happens. Absolutely.

11:56

Yeah, so the planet seems to have

11:58

this innate capacity to regulate its... climate

12:00

to some extent. It can pull itself

12:02

back from these extreme hot house states

12:04

or these deep freezes. But the process

12:06

by which that happens is so

12:08

slow that it is simply not

12:11

relevant to human societies or even to

12:13

any particular species most of the time.

12:15

We definitely cannot rely on that planetary

12:18

balancing act. We have

12:20

to intervene and

12:22

correct the severe imbalance that we've

12:24

introduced. But it is astonishing that

12:26

the planet, that the Earth system

12:28

as a whole, kind of has

12:30

this innate, albeit very slow and

12:32

limited, capacity to keep itself in

12:35

a more temperate climate and a more habitable zone. What

12:38

do you think the implications of

12:40

changing this mindset will

12:43

be? Like if we do start thinking about Earth

12:45

as a living thing? I

12:47

think there are some really important implications

12:49

of this kind of conceptual shift. I

12:51

think the first thing to recognize is

12:53

that in some ways we're like all

12:55

other life. Life changes its environment all

12:57

the time. So we're the most recent

12:59

chapter in this really long co-evolutionary saga.

13:02

But in other ways, we're highly unique

13:04

compared to other life forms because we're

13:06

really the only creatures on the planet

13:08

that can consciously understand and deliberately

13:10

change the entire Earth system as

13:13

a whole. And so all life

13:15

is participating in the system, but

13:17

we're actually aware of our actions and

13:19

their consequences. That gives us a

13:21

unique privilege and responsibility. And I would

13:23

even argue a moral obligation, not just

13:25

to each other as people, as humans,

13:27

but to the larger living entity, the

13:29

larger system that we are a part

13:31

of. I think there's an

13:34

immense difference between thinking of ourselves as

13:36

inhabitants of the planet or quote, passengers

13:38

on spaceship Earth, versus being

13:40

literally continuous with the planet. So

13:43

to save the planet is literally to

13:45

save ourselves. We

13:49

are all extensions of Earth and everything we

13:51

do is looping back to change the planet

13:53

in some way. So we are empowered in

13:55

that sense. Ferris,

14:00

thank you so much for talking to us

14:02

today. I've started to think about Earth differently

14:04

just in this conversation, so thank you so

14:06

much for sharing your book with us. Thank

14:09

you so much. It's a pleasure to be here. Ferris'

14:12

book, Becoming Earth, How Our Planet Came

14:14

to Life is out tomorrow, June

14:16

25. See our episode

14:18

notes for a link to the book. This

14:20

episode was produced and fact-checked by Burleigh

14:23

McCoy, edited by our showrunner, Rebecca Ramirez,

14:25

and the audio engineer, Wes Quasey Lee.

14:28

Pat Donovan is our senior director and

14:30

Colin Campbell is our senior vice president

14:32

of podcasting strategy. I'm Regina

14:34

Barber. Thanks for listening to

14:36

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