0:00

I'm Dr Karl, coming to you from the lands of

0:02

the Gadigal people of the Eora Nation.

0:04

I acknowledge Aboriginal and Torres Strait Islander

0:06

peoples as the first Australians and

0:09

traditional custodians of the lands where we

0:11

live, learn and work.

0:15

G'day, Dr Karl, Shorelands of Science, University

0:17

of Sydney with Professor Geraint Lewis. Hi, G'day Karl,

0:19

how's it going? And you have been

0:21

holding out on me. You didn't tell me something I should have

0:23

known. What's that now?

0:25

You did educate me about the standard

0:27

candle. Yes. So that way you can

0:30

work out distances in

0:32

the universe. And so if there's

0:34

a light in the sky or on the ground, you don't know

0:36

whether it's really bright far away

0:38

or really dim close up. And

0:41

so if you've got standard candles, you can sort of work

0:43

out distances. But you did not tell me

0:45

there was a thing called a standard distance?

0:47

No, a standard ruler. A standard ruler. Yes.

0:50

You did not tell me this. And it's tied in with something called baryons

0:52

and baryon acoustic oscillations. I had to look

0:54

up baryons. And apparently they're a composite subatomic

0:57

particle which contains an odd

1:00

number of valence quarks.

1:03

So a neutron and a proton

1:06

would count as a baryon. Correct. Yes.

1:09

And then there's this thing called baryon acoustic oscillations,

1:11

which I had to look up in the font of all knowledge because

1:14

you weren't here. I had to go to Wikipedia. And

1:16

that tells us something about a giant bubble

1:18

that some of your colleagues have discovered recently.

1:21

Where do we start? I want to think of this like a

1:23

fossil.

1:24

A fossil? A fossil from the early universe. Let's

1:27

start at the beginning. Yep. Okay,

1:29

so Big Bang. Right? So universe

1:32

after the fiery part of the Big Bang,

1:34

right? So it's got a mix

1:36

of matter in there. So there's dark

1:38

matter, which is the dominant mass in the universe. Oh,

1:41

when do we think that cooled down? We don't know. Don't

1:43

even ask. It probably formed around the same time as normal

1:45

matter, but we don't know. It was very early on, maybe,

1:47

you know, fractions of a second after the Big

1:50

Bang. But the nuclei formed around three

1:52

minutes of hydrogen heat? Correct. We

1:54

won't even waste our time thinking about dark matter. The dark matter's part

1:57

of the equation. Oh, it's an important part of the equation. Very

1:58

important, okay, so. You've also

2:01

got hydrogen and helium but

2:03

as you said the universe is still very hot so

2:05

the nuclei are separated from

2:07

the electrons. And this

2:10

is at the three minutes until 380,000 and by the

2:12

way we're heading towards this giant

2:14

bubble of galaxies a billion light

2:16

years wide. Yes. This is late 2023. Yeah

2:18

so you've got dark

2:22

matter, you've got protons and

2:25

helium nuclei and your electrons buzzing around

2:27

and this is a state of matter known as a plasma.

2:30

Plasma you can think of as

2:33

a bunch of atoms where the electrons have

2:35

been ripped off. Yes. Is it a sea

2:37

of nuclei floating in a sea of electrons?

2:39

Yeah yeah but there's also light

2:41

radiation bouncing around.

2:44

So it's that light that stops the electrons

2:46

joining back with the atoms. Every time an electron

2:48

gets close to an atom and thinks oh I'm going

2:50

to join up and become a neutral atom along

2:53

comes some high-energy light smack and

2:55

hits the electron back off again. Okay so it's in a dynamic

2:57

situation. So it's a plasma

2:59

and plasma behaves somewhat

3:02

differently to normal matter. What

3:04

that means is because you've got these free floating electrons

3:07

it means that light can't travel long

3:09

distances in a straight line. It keeps bouncing

3:11

off electrons. And most of the matter,

3:14

regular matter in the universe is plasma which is stars.

3:17

Yes. Today. Yep. But it went

3:19

through a period of when it was neutral we've got to get

3:21

to that point first. Right but today stars

3:24

are plasma. Yeah. And then most of what we

3:26

call the regular matter. Is all the plasma.

3:28

You're saying it takes more than just

3:30

a few seconds for light to go from the center of the Sun

3:33

to the surface if it's a plasma. Oh yeah

3:35

it takes a hundred thousand years. A hundred

3:37

thousand years? Yeah. Because that's the bounce of all

3:39

of the electrons all the way through. So a

3:41

hundred thousand years to the surface and then eight minutes

3:44

to get to the Earth. Okay. So early

3:46

universe dark matter starts

3:48

to collapse. So it's not completely smooth. There

3:50

are places where there's a little bit more dark matter than other

3:52

places. So you start to get dark

3:54

matter gathering right. Gravity starts to pull

3:57

it together. We're very sure that

3:59

dark matter exists. We know that it interacts

4:01

via gravity. I don't know what

4:03

it's made of. It doesn't seem to interact with

4:05

electromagnetic radiation. Yes. But

4:07

it definitely exists. It exists. Okay,

4:10

right. Okay. So dark matter starts to

4:12

collapse down and forms the sites of the first galaxies and the first clusters.

4:15

That's where these objects are going to move. Dark matter, is that important?

4:17

Yes. It's the framework in which all galaxies are

4:19

formed. What? Yes.

4:22

You've got this region where you've got dark matter accumulated and of course that

4:24

pulls on the plasma. So the plasma

4:27

gets pulled as well. So the electrons and

4:29

the nuclei and because light

4:31

is bouncing off the electrons, light is being

4:34

pulled as well. And light is electromagnetic

4:36

radiation of any frequency radioed

4:38

together. Okay, right. Now the

4:40

dark matter collapses down. It collapses, it

4:42

collapses. It starts building up the sites of galaxies.

4:46

In comes this plasma. Now plasma

4:48

is like it can behave a bit like

4:50

a fluid. It can slosh. It

4:52

sloshes. It interacts, right? So

4:55

imagine it comes into this well and

4:57

you pour this material in and there's a slosh

5:00

and a splash and that splash radiates

5:03

as a sound wave back

5:05

out into the plasma. So a sound wave

5:07

is where energy is transmitted by

5:10

one particle hitting another. I kind

5:13

of think of people in a line or

5:15

a queue at a bus stop and one person

5:18

pushes the next two pushes the next two pushes the next. So

5:20

that's how sound waves transmit

5:22

energy from your lips onto

5:24

my eardrum. Individual molecules

5:27

bang into each other and carry the energy.

5:30

So this is acoustic sound. Faryon

5:33

acoustic oscillations. Keep going. The

5:35

sloshing of the plasma, you imagine like you drop a

5:37

stone in a pond, that sound wave ripples

5:40

out. Yep, right. Now this is happening

5:42

in lots of places in the universe at the same

5:44

time. So you imagine you throw a pile of stones

5:47

into a pond. You start off these ripples

5:49

which spread outwards in the plasma

5:52

and they spread out because the plasma is behaving

5:54

like this fluid until you get to 380,000 years. the

6:00

universe is just this plasma. And

6:03

it's sloshing around. Why is it sloshing? Is it they're

6:05

attractive and repulsive forces? Yeah,

6:07

yeah. What are the attractive forces? What are the repulsive forces? It's

6:10

all electromagnetic. It collides and bounces,

6:12

right? Going... It's always to be attractive

6:14

of gravity and repulsive of the similar charges.

6:17

Yeah, you can think about it that way. But it's

6:19

a large scale thing. Even though you know water

6:22

is made of molecules attracted to

6:24

each other by electrification, it sloshes, right?

6:26

Yep. On a large scale. Yeah, you set up

6:28

waves and you get the same kind of sloshing in

6:30

the plasma. So you get to 380,000

6:32

years. Yep. The universe is cooled

6:34

down to a point where the electrons

6:37

can join the nuclei. The

6:40

universe became neutral. The

6:43

electrons joined with the protons and

6:45

with the helium nuclei. The first

6:47

thing that happens is that light

6:49

can now just free stream. There's no free electrons about

6:51

it. It just off it goes into the universe. So the

6:53

universe becomes transparent? Really?

6:56

Yes. And it stops being

6:58

a plasma. We haven't got

7:00

stars yet. No, no, we haven't got stars yet. So what happens

7:03

is that sloshing is now

7:05

turned off because everything's not behaving like a fluid

7:07

anymore. Because it's only a fluid when it's a plasma.

7:10

Once it becomes neutral, it just becomes a gas and

7:12

just... That's it. So

7:14

what that means is the pattern, like

7:16

if you imagine that you take a picture of the

7:18

surface of a pond that you've thrown some stones in, that

7:21

pattern of ripples gets frozen

7:24

into the universe. Up

7:27

to 380,000 years, we had these sound waves

7:29

traveling through the universe. At 380,000

7:32

years, once it becomes neutral, those sound

7:34

waves can't travel anymore because they

7:36

can only travel in a fluid. And

7:39

that fluid, which was the plasma, no longer

7:41

exists. How does this

7:44

relate to the CMB, the cosmic microwave

7:46

background? The cosmic microwave background is the

7:48

light that's released at 380,000 years. The

7:50

light being any electromagnetic frequency. You're

7:53

going to have to live with this. I'm not sure... It bothers

7:55

me. Why people think light is only visible. Because

7:57

I spent two years of my life designing and building

7:59

a... machine to pick up electrical signals off

8:01

the human retina. As far as I was concerned

8:03

I was picking up light and light was 400 to 700 nanometers

8:06

and that was it. I've

8:09

got to get rid of that small-minded

8:11

approach in my brain. So the

8:14

CMB, the Cosmic Microwave Background,

8:16

do you pick that up with radio telescopes? It's

8:19

in the microwave radio region yes. So

8:21

there's a couple of centimeters wavelength. Yes. Today.

8:24

Today. Back then it was different. It was high energy

8:26

up until that point you could rip an electron off an

8:28

atom but the expansion of the universe has

8:31

cooled that light down and it's gone cooler

8:33

and cooler. There was a time when the universe was

8:35

blue and then it was green and then eventually

8:38

cooled down and now it's in the microwave part

8:40

of the spectrum. We've got to tie this

8:42

to firstly this bubble of galaxies a billion

8:44

light years white and how you've been holding out on

8:46

me that there is a standard length.

8:49

Yes. There's a standard candle. Alright.

8:52

But there's also in the universe a standard length

8:54

as you call it. Okay so 380,000 years. Yep.

8:56

So the gas is

8:59

smoothly distributed right? In the peaks

9:02

of the waves there's more gas than not

9:04

in the peaks of the waves. Sure. So when

9:06

that light is emitted, what we see

9:09

as the CMB today, in some

9:12

places it's come from regions with little

9:14

matter. Yep. In other regions it's come from

9:16

places with lots of matter and that gets imprinted

9:19

onto the cosmic microwave background. If

9:21

there's a lot of matter, yep, the photon

9:23

actually loses a tiny bit of energy climbing

9:26

away from that region because it's got a bit more gravity.

9:29

Ah. Yep. So when we look at the cosmic microwave

9:31

background we actually see a pattern. It's got a rippled

9:33

pattern on there. Now we understand

9:35

the physics of plasma, we understand

9:37

the physics of dark matter and

9:40

that means that we can predict

9:42

how big the ripples are in our cosmic

9:44

pond. They have a particular size

9:46

scale to them. So the

9:49

ripple, like if I throw a stone in a pond,

9:51

the ripple goes out to be a meter after

9:53

a second or so. I know

9:56

that the pattern written on the sky contains

9:58

circular effectively

10:01

of this particular size. We

10:03

don't measure those sizes directly,

10:06

we measure their angle, how big

10:08

are they on the sky in terms of degrees

10:10

on the sky. If

10:12

I know how big they really are,

10:15

they're a certain length which I can calculate from the

10:17

physics, and I take the angle

10:19

that I see them with, I can work out

10:21

the distance between me and

10:24

the ripple on the cosmic microwave background. Right.

10:27

In our cosmological equations, that

10:29

angular size depends upon

10:32

the makeup of the universe and how the universe

10:34

has expanded. So we can use that size

10:36

that we see the ripples on the cosmic microwave

10:39

background to tell us about the

10:41

evolution of the universe. So

10:43

this is this fossil information?

10:47

Yeah, what we are seeing is an imprint of the

10:49

universe as it was at 380,000 years. We

10:52

think we know how far things were apart

10:54

at that time, and so we can then

10:56

use that, measure the angle and calculate

10:59

how the universe has changed from 380,000

11:01

years to today. But

11:03

hasn't the universe expanded as well

11:06

in that time? Yep. So therefore we'd be,

11:09

how do you know what a standard size is? A standard

11:12

angle, because if it's expanded the angle would be

11:14

smaller back then and bigger now. No, no, no.

11:16

An angle is something that I measured today, Carl.

11:19

Right. But how do you know what the angle was back then? Because

11:21

I know the physics of how plasma sloshes

11:23

around for 380,000 years. Imagine

11:26

I plonked you down in the universe 380,000 years

11:29

and I asked you to hold up a meter stick. Yep. That

11:32

meter stick, I see that at a certain angle on

11:34

the sky. Where are you from? Today. From,

11:36

oh, okay. Yep. So you're looking back

11:39

to that radiation that was released at 380,000 years

11:42

to run free when the universe became transparent.

11:44

Right. Now, if I know that it's

11:47

really a meter stick you hold in and

11:49

I measure the angle, I can calculate the distance to you. Yes?

11:51

Trigonometry. Yep. Yeah, you familiar with trigonometry?

11:54

Yep. I love trigonometry. Okay,

11:56

good. It's one of my favorite things at school. I

11:58

can use the angle that I... see

12:00

that meter rule to tell me about how the universe

12:03

is expanded between the time

12:05

that the light left you, left the

12:07

meter rule, and arrived at me today. Okay?

12:11

Yep. Imagine I measure it and it's, I'll just make up

12:13

a number, one degree here. If

12:15

I was actually in a different universe with a different

12:17

expansion and different mix of energy and matter,

12:20

I might say, oh, that angle should be half a degree

12:23

or two degrees. The angle depends

12:25

upon the evolution of the universe. The meter

12:27

rule is still a meter rule. What

12:30

we're saying is that at 380,000 years, we can

12:32

calculate the length of the meter rule. That's the pattern

12:34

that's imprinted on the cosmic microwave background.

12:37

In this article from Wikipedia on baryonic acoustic

12:40

oscillations, they talk about the length of

12:42

this standard ruler, roughly 500

12:44

million light years or 170 megapar things in

12:48

today's universe. In today's universe. Right.

12:51

So remember, the gas that we left at 380,000 years is

12:54

not going to just sit there. Some of it's going

12:56

to start to collapse down into stars

12:58

and into galaxies and places

13:00

where there is more gas is going

13:02

to collapse down into more stars and galaxies

13:05

than places where there is less gas. The

13:08

pattern that we see written on the cosmic microwave

13:10

background gets turned into

13:12

a pattern on the distribution

13:15

of galaxies in the universe. That's like

13:17

the seed of today. Yeah. So the

13:19

pattern that we see in the cosmic microwave background turns

13:21

into the pattern of where the

13:23

galaxies end up. There will be more

13:25

in the peaks of the waves and less in

13:27

between. What does it mean, the standard

13:30

rule? Is that the diameter of the universe back then? No.

13:33

Again, I drop my stone in the pond, plop, the

13:35

ripple goes out and so there's a radius

13:37

out to that ripple. To the first peak, for

13:40

the center of the peak. Right. That

13:42

distance, which is our standard ruler, the

13:44

universe has continued to expand. So those ripples

13:47

have continued to get bigger. And

13:49

what this is saying is that today

13:52

those ripples would be spheres,

13:55

right? They're spheres in three dimensions with

13:57

a radius of around whatever this number was. Five hundred

13:59

million. I said that's half of

14:01

this billion light year wide thing. Yes.

14:04

Ah, now you get it. So what

14:06

these guys are saying is in this newspaper, which

14:08

is by Brent Talley, who's been doing galaxy distributions

14:11

forever, and my colleague, Colin

14:13

Howlett, at the University of Queensland, what

14:16

they've done is they've gone and looked at the distributions of

14:18

galaxies around us. Galaxies are

14:20

a little bit all over the place. There's lots of evolution

14:22

that's gone on since the Big Bang. But

14:24

what they've said is that they've found essentially

14:27

a shell of galaxies, a bubble,

14:30

which is roughly a million light

14:33

years across. A billion. A billion, maybe. A

14:35

million billion. Yeah, the astronomers factor

14:37

it. It's the same thing. So what they're saying is

14:40

that, oh, that shell

14:43

looks like it could be one

14:45

of the ripples. They've identified one of the ripples

14:47

in the early universe. So in the early universe, there

14:50

was a splash. When outwards, gas

14:52

was there. And then over the history of the universe,

14:55

that formed galaxies. And

14:57

what they're saying is this billion light

15:00

year bubble of galaxies, so the

15:02

shell of galaxies. And that shell

15:04

is a fossil that was started

15:07

back before 380,000 years because

15:09

one of those ripples in the plasma evolved

15:12

into these galaxies that we can see today. And

15:15

so we've got this kind of a peak

15:17

of galaxy formation around the

15:20

classic distance from the center of half a billion light

15:22

years. Yes. And it's not like zero

15:25

stuff inside. No, no, no. There's still stuff

15:27

inside that bubble. There is stuff inside. So what

15:29

we've seen is like an enhancement due

15:31

to this bubble. Remember, it's sound waves. So

15:33

sound waves, when they travel to the air, it's not like there's

15:35

a packet of sound in a vacuum behind it, right?

15:38

You have a peak and a trough, but there's

15:40

still material between the peaks. And

15:42

that's what we've got here. There's still galaxies formed

15:45

between the peak of that bubble that's

15:47

spread out due to this sloshing

15:49

of the plasma in the early universe. So

15:52

this newly found bubble of galaxies a billion

15:54

light years wide is a soft proof

15:57

of the concept of the baryonic

15:59

kind of oscillation or

16:01

that already proved in the past? There's an awful lot of evidence

16:03

for the barium acoustic oscillations. I mean

16:06

I could direct you to lots more reading. It's

16:08

not that we just predict a peak, but

16:11

as I say if you imagine we throw a bunch of

16:13

stones into a pond you predict a

16:15

whole range of peaks right because you get peaks

16:17

overlapping with peaks and so the barium acoustic oscillations

16:21

is more than one wave it's a bunch of wavelengths

16:24

and so that's what we see on the cosmic microwave

16:26

background and that's also what we sort

16:28

of see imprinted on the galaxies around us

16:31

as well is we've identified statistically

16:34

overall there's this peak but what

16:36

they've done is said right we have found this

16:38

in one particular object so rather

16:40

than a statistical average over everything and

16:42

finding the result they're saying ah look

16:45

this is where there's actually one of these bubbles

16:48

in its raw self basically. And

16:50

this is based on some sort of many observations

16:52

including some from the Sloan Observatory

16:55

where they looked at 47,000 galaxies. Yeah the Sloan

16:57

Telescope in New Mexico

17:00

is probably one of the most productive telescopes that's

17:03

ever been built. What? It was used to

17:05

undertake what was known as the Sloan Digital Sky

17:07

Survey. That survey looked at stars

17:09

in our galaxy to quasars at the edge of

17:11

the universe. They just did this huge survey

17:13

collected an immense amount of data and

17:16

they've generated so many results

17:18

on stars in the hail of the Milky Way to galaxy

17:21

distributions to quasars that are out there.

17:24

An immensely successful telescope.

17:26

And have you been to it? I have not been to it. It's not

17:28

particularly big either. I thought it was only a couple of meters across

17:30

or something. That's old. It was first

17:32

started in the I

17:34

think maybe late 80s early 90s. I

17:38

remember rightly I might get sorry. It was

17:40

built with philanthropists money

17:42

I think originally I think that's where the Sloan in the Sloan

17:44

Digital. There was a Sloan who was big in General Motors.

17:46

Yeah. They didn't need to

17:48

build a 20-meter telescope. They just

17:51

needed a telescope that they could use to

17:53

dedicate to a survey. A boring

17:56

survey. Not boring. It's important

17:58

the wrong way. a

18:01

methodical. This bubble of galaxies

18:03

a billion light years. Why well isn't the

18:05

Hubble limit of the universe where things

18:08

reach the speed of about 15 billion light

18:10

years and the observable universe about 43

18:13

billion light years away from us? It's

18:15

something like that. But isn't that a

18:18

significant percentage? Would

18:21

there be more of these bubbles

18:23

if we go looking? Yes, there should be. There should

18:25

be. I mean the reason

18:27

that we can see this one directly is

18:29

that it's relatively close by. Yeah,

18:32

a quarter of a billion light years from us. At the edges

18:34

a quarter of a billion. So it was well

18:36

surveyed using Sloan. Oh, it would

18:39

be hard if it was way on the other side of

18:41

the observable universe. Yeah, it's

18:43

nearby so it's that big size today.

18:45

In the past it would have been smaller. We will

18:47

find more once we have the next generation of telescopes

18:50

etc. But this is like the first one where they can go, look,

18:52

this has got all the properties of a

18:54

fossil bubble from the early universe. Oh

18:57

my God, so this is related to the standard

18:59

length of the universe. Standard

19:01

ruler. Standard ruler. So can you explain

19:03

for me just before we go the standard ruler again?

19:06

Standard ruler is something whose intrinsic

19:09

size you know. How tall are you Carl? Okay, 1.87.

19:14

Now if I took you and scattered you through the universe

19:16

I would know that everywhere I see a Carl you

19:18

would be 1.87 meters. Model copies of me.

19:21

Okay, yep. The way that we observe an object

19:23

depends upon the evolution of the universe. The

19:25

time that the light was emitted from one of the Carl's

19:28

to when it's received. So that means

19:30

that I would see all those Carl's

19:32

out there at different angles. And

19:34

the distribution of angles tells

19:37

me how the universe is evolving. In

19:39

the same way as the distribution of standard candles,

19:42

tells me how the universe is evolving because how bright

19:45

an object appears depends upon how

19:47

the universe is expanded between the

19:49

light being emitted and the light being received. All

19:52

this time there's been this thing of the standard ruler

19:54

and I didn't know it. It's

19:56

a tricky one to deal with because unlike

19:58

you 1.87. Most objects

20:01

don't come with the standard size written on them. There's

20:03

a famous sketch from Father Ted. Do you

20:05

know Father Ted? No. I'm

20:08

sure some of you listeners do. There's a famous one

20:11

where he's sitting in a caravan with another

20:14

priest, Father Dougal, who's not the brightest.

20:17

And he's got a little model cow. And

20:20

he's going, this one

20:22

is small. Those are far

20:24

away. Far away. And he's

20:26

trying to explain this concept, right? But we

20:29

have the same thing in the universe. I see an elliptical

20:31

galaxy on the sky.

20:33

How far away is it? Well,

20:35

I don't know how far away it is. I

20:37

need to know how big it is so

20:40

I can work out what angular

20:42

size I expect to see it from the Earth,

20:45

right? But the problem is, elliptical galaxies,

20:47

they can be small, medium,

20:50

large, and very large. And

20:52

they can appear very similar on the sky. Spiral

20:54

galaxies are the same. It's

20:56

very hard to nail down your standard

20:59

rulers because it's the standard

21:01

part that is difficult. So,

21:03

tell us about your books so they can find them as we head out of

21:06

here. There's A Fortunate Universe, The

21:08

Cosmic Revolution in His Handbook, and Where

21:10

Did the Universe Come From? and Other Cosmic Questions.

21:12

And I've got 47 books in

21:15

various places on Earth. Just go

21:17

look on my homepage, drkarl.com, D-R-K-A-R-L.com,

21:21

or Amazon, or Booktopia, or anywhere.

21:23

Just see what you can find. Thank you so much for

21:26

explaining. I'm beginning to slowly get it. Now,

21:28

dear audience, if you have to listen to this more than

21:30

once, do so. It's really worth it. And

21:33

why don't people send questions to you, Karl, and then I'll

21:35

have another go at answering them. Oh my God, that's a good idea.

21:37

Okay, so send them to

21:40

drkarl.com, D-R-K-A-R-L, and we'll protect

21:42

you from the answers

21:45

and not increase your email. Thank

21:48

you very much.

21:49

Thank you. Bye. Bye. Bye.

21:52

40 years after my very first story on climate

21:54

change, I'm still on the case. But

21:57

now I've decided to write a book

21:59

on it. It's Dr Karl's

22:01

little book of climate change science and

22:04

it will explain how we got into this

22:06

mess and how we can get out

22:08

of it. You'll find out who

22:10

did the early research into climate change

22:12

and then spend billions of dollars

22:15

trying to cover it up and why they

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did that. We'll find out how greenhouse

22:19

gases trap 400,000

22:22

Hiroshima atom bombs worth of heat every

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day and

22:27

how we can stop and even reverse

22:29

global warming. Dr Karl's little

22:32

book of climate change science. Get this book

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while it's not hot. We

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22:42

It's available as a paperback, e-book and

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audio book from your local bookshop,

22:47

library or online. Shirtloads

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aired by the University

22:53

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