Latest / Saving the World From Bad Ideas / Bad Idea #49 "We can stop worrying about the climate" with Zeke Hausfather

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Bad Idea #49 "We can stop worrying about the climate" with Zeke Hausfather · Saving the World From Bad Ideas

0:00
So our best estimate removing sort of natural variability is
0:04
that the current rate of warming due to human activity is
0:07
somewhere in the order of .27 C, So about a 40% increase in the
0:12
rate of warming compared to what we saw since 1970.
0:15
And that's attributed primarily to reductions in planet cooling
0:20
aerosols on top of continued emissions of, of CO2, another
0:23
greenhouse gas. Get rid of sulfur dioxide
0:25
emissions completely in other aerosols and keep other
0:29
greenhouse gas concentrations. You would end up at about two
0:32
degrees of warming rather than the 1.5 or 1.4.
0:35
If you go back to Al Gore's An Inconvenient Truth, you know,
0:38
back in 2006, he had this great skit from Futurama, the the
0:42
classic sci-fi show where they're talking about climate
0:45
change and they come up with a solution, which is to drop a
0:47
bigger and bigger ice cube in the ocean every year, thus
0:49
solving the problem once and for all.
0:51
And all of these geoengineering approaches we're talking about
0:53
marine cloud brightening, sulfate aerosol injection, etc,
0:56
are literally that right for where we're at today.
1:00
Welcome to saving the world from bad ideas.
1:02
I'm Mark Linus, and I've had a few bad ideas in my time.
1:06
I used to go out in the night time to destroy GMO crops, and I
1:09
also opposed nuclear power. But then when I looked at the
1:11
science, I found I got it wrong. Oops.
1:14
I've learned the hard way that none of us are right all the
1:16
time. So now I'm here to challenge the
1:18
assumptions that we all too often take for granted because
1:21
the future depends on us getting it right.
1:24
My guest today is Zeke Housefather whose climate
1:26
research lead at the financial companies Stripe Lights on
1:31
Carbon Brief has been an IPCC lead author and also has a sub
1:35
stack called the Climate Brink. Zeke welcome.
1:39
Thanks. Great to be on.
1:41
Well, thank you for being with us.
1:43
Of course we need to have a bad idea.
1:45
This is all about saving the world from bad ideas.
1:47
And there's a couple of of bad ideas that occurred to me.
1:52
I thought one that we might attribute to you or that you can
1:55
combat, which would lead into a whole discussion, which I really
1:59
want to have about aerosols and how much the planet is heating
2:02
up as a result of air pollution controls.
2:05
So the bad idea actually could be pollution controls on
2:08
shipping. So I'll leave you to ponder that
2:11
and we'll get into the discussion.
2:13
Then we'll come back and see whether that's actually the
2:15
right, the right direction to go in, because there's one or two
2:17
other things that we could propose as well.
2:18
But give us a sort of broader context at the moment of how bad
2:25
that global warming is getting, how rapidly is, is the planet
2:29
heating up? Because I think there's a sense,
2:31
certainly I have the sense that things have got worse and
2:34
there's been a real acceleration in the warming trend in the
2:37
last, well, maybe year or two. Yeah.
2:40
So if you look at the period since 1970, which is really the
2:44
the time frame over which, you know, our emissions of CO2 and
2:46
other greenhouse gases picked up substantially, the world had
2:50
been warming at about .2°C per decade or about two C per
2:54
century. In the last 15 years that has
2:56
started to change. You know, if you draw a straight
2:59
line through the last 15 years, it's actually twice as fast
3:01
point 4C per decade. But that's a little misleading.
3:04
There's a big El Nino event in 2023-2024 that bumps that up a
3:08
bit. And so our best estimate
3:10
removing sort of natural variability is that the current
3:14
rate of warming due to human activity is somewhere in the
3:17
order of .27 C. That's about a 40% increase in
3:21
the rate of warming compared to what we saw since 1970.
3:24
And that's attributed primarily to reductions in planet cooling
3:29
aerosols on top of continued emissions of of CO2 and other
3:32
greenhouse gases. If we're just continuing our
3:34
greenhouse gas emissions, the world would be warming still
3:37
around .2 C per day, maybe a tiny bit more.
3:39
But a good chunk of the bump above that appears to be due to,
3:42
you know, cutting the pollution that had been masking a fair bit
3:45
of our historic warming. Yeah, I'm, I really want to get
3:48
into this because I think it's something that people in general
3:51
have absolutely no idea about. There's literally no public
3:55
discussion. I mean, we all talk about it
3:56
because we're Climate wants you more than anyone, which is why I
3:59
want to talk to you about this because I think it's such a
4:02
critical issue that we are removing the, the masking
4:07
effects of aerosols and revealing this underlying rapid,
4:12
rapid global warming. And let let's kind of drill down
4:15
into the details. What's how much cooling were
4:18
these pollution? What was this pollution giving
4:21
us in the past and what's changed?
4:23
So to back up a little bit, aerosol is the sort of a wonky
4:26
term that we use to cover a small particles that are
4:30
suspended in the atmosphere. The one that really matters from
4:33
a climate cooling perspective is sulfur dioxide.
4:36
And sulfur dioxide has two primary effects on the climate.
4:39
1 is that it itself is quite reflective, so it scatters a
4:42
certain amount of incoming sunlight back out to space
4:45
before it gets absorbed by the planet's surface.
4:47
That's what we call the direct aerosol effect.
4:50
And the other more important one is its role in cloud formation.
4:53
Now, if there's too few particles in the air, it's a lot
4:56
harder for clouds to form. It's one of the reasons
4:59
naturally we have more clouds over at the oceans is because
5:01
the amount of sea salt aerosols that are sort of naturally
5:04
present. So that can increase cloud
5:06
formation. And so humans, by emitting lots
5:08
of sulfur dioxide as a byproduct of burning fossil fuels, have
5:11
been increasing the prevalence of low lying clouds that
5:15
themselves are fairly reflective and bounce more light back to
5:17
space. So same ultimate mechanism of of
5:20
reflectivity, but a more indirect effect on cloud
5:23
behavior. And so the combination of those
5:25
factors has led to about half a degree CA centigrade of cooling
5:30
that's gradually ramped up over the 20th century, sort of peaked
5:35
in its magnitude around the year 2000 and then has been declining
5:39
in more recent years as we've cut sulfur dioxide pollution and
5:42
other aerosols. Yeah, and that's that, that
5:45
figure of .5 degrees, half a degree of centigrade is, is
5:50
really quite extraordinary because given that we're already
5:53
1.5° above pre industrial, which is the Paris Agreement limit, if
5:59
we were to continue removing all of the remaining pollution
6:03
that's in the atmosphere, all of these aerosols are the
6:05
byproducts of fossil fuel burning and other things, then
6:09
that half a degree would manifest and we'd be straight at
6:11
2°. Am I wrong about that or is
6:14
there a reason to be concerned? So that's roughly right.
6:17
If you were to get rid of sulfur dioxide emissions completely
6:21
and, and, and other aerosols and keep other greenhouse gas
6:25
emissions or concentrations, I should say the same as they are
6:28
right now, you would end up at about two degrees of warming
6:31
rather than the 1.5 or 1.4 we're at today.
6:34
And and again, that's because we would have been at that anyway,
6:38
except for these aerosols are masking some of the historic
6:41
warming from greenhouse gases. Now, in reality, it ends up
6:45
being a little bit more complicated than that because
6:48
not all greenhouse gases are created equal.
6:50
So aerosols are very short lived.
6:52
If I stop emitting sulfur dioxide from a coal-fired power
6:55
plant, most of that sulfur falls out of the lower atmosphere in a
6:59
couple weeks. CO2, the main greenhouse gas
7:01
driving warming is very long lived.
7:03
It takes the the lifetime of CO2 in the atmosphere is
7:06
complicated, but let's just say it takes, you know, many
7:07
centuries for, for CO2 to dissipate and and millennia for
7:10
the warming of CO2 to avoid dissipate.
7:12
But there's the intermediate greenhouse gases, things like
7:15
methane that aren't quite as short lived as sulfur dioxide,
7:20
but it's still a pretty short lifetime.
7:21
So methane amid today is most of that is going to oxidize the
7:25
next 10 to 12 years through a chemical sink interactions with
7:28
the OH radical in the atmosphere and turn into water vapor and
7:33
carbon dioxide. And so it turns out that the
7:36
warming from methane in particular is close to, but not
7:41
quite as big as the cooling we get from sulfur dioxide and and
7:46
other aerosols. And this if you add in some
7:48
other short lived climate pluton some some types of like
7:51
hydrofluorocarbons and nitrous oxide, which is not super short
7:55
lived, but it's, it's much shorter lifetime than CO2.
7:58
Essentially what we find is that if we actually were to get
8:00
greenhouse gases and aerosols to 0, temperatures would remain
8:05
fairly flat. And the reason for that is
8:07
because the warming from these shorter lived greenhouse gases
8:10
would roughly counteract the cooling from the aerosols that
8:14
we're getting rid of. So that maybe that's another bad
8:18
idea, which I was also going to suggest, which is that the, this
8:22
idea that the Earth will continue to warm the decades to
8:26
come, even if we stop all the emissions tomorrow or even if we
8:28
get to net zero. It's that's a very prevalent
8:30
idea. People use it as a basis for
8:33
being extremely pessimistic about the future.
8:35
And it sort of, you know, implies that if you what it sort
8:39
of implies there's not much money, you're doing anything
8:41
because all this warming is already in the pipeline.
8:43
We're already committed to to passing tipping points and to
8:46
getting to extreme levels of heating.
8:47
So just repeat this perhaps in well a bit more slowly.
8:52
Like why does does getting to net zero stop warming or not?
8:57
So our best estimate is that getting to net 0 emissions of
9:02
all greenhouse gases and aerosols would lead to roughly
9:06
flat temperatures. Similarly, just getting to net
9:08
zero CO2 emissions and holding everything else constant would
9:11
also get you to roughly flat temperatures.
9:13
And the reason for this and the reason why there's some
9:16
confusion in the public about this fact, it actually has a
9:19
fairly interesting back story. So if we go back 20 years, it
9:23
was, you know, the earlier days of climate modeling.
9:26
And most climate models, almost all climate models back then
9:29
didn't have biogeochemistry. They didn't have a dynamic
9:33
carbon cycle. They weren't representing the
9:35
growth and death of vegetation and sort of ocean CO2 uptake and
9:39
all these other complicated things.
9:40
They were, they're primarily atmospheric models.
9:42
And so the way that those models were often tested is if you
9:45
double the amount of CO2 in the atmosphere in the model, you
9:49
look at what happens and that's a good metric for the warming
9:52
you can expect. And it turns out if you do that,
9:55
if you double the amount of CO2, say we're at, you know, 420
9:59
today. If you double that to 840, you
10:01
end up getting pretty rapid warming, but then continued
10:05
warming for a couple centuries after that until the system
10:07
reaches a new equilibria. And because of that continued
10:10
warming, if you hold the amount of CO2 in the atmosphere
10:12
constant, there was this assumption that, you know, well,
10:15
there's warming in the pipeline because at a certain level of
10:17
CO2 concentrations, it takes a while for the Earth's system to
10:21
catch up. Why that's wrong is because
10:24
holding the amount of CO2 in the atmosphere constant is not a
10:28
very logical thing to expect in the real world.
10:31
So if I wanted to hold the amount of suit to constant just
10:33
at today's levels at 420 per million, I'd have to pretty
10:37
rapidly ramp down emissions. You know, not instantaneously
10:41
overnight, but ultimately get to somewhere around, you know, 20%
10:46
of current global emissions after five years and then very,
10:50
very slowly reduce that after that point.
10:52
But it'd still be emitting a, you know, giga tons of CO2 per
10:55
year just to maintain current concentrations at 400 point.
10:59
Just explain that a bit. Is that that's because the
11:01
oceans and the biosphere are removing carbon dioxide from the
11:05
atmosphere all the time, right? So to hold exactly, still have
11:07
to be emitting some. Yeah.
11:09
So about 60% of the CO2 that we emit today gets absorbed over,
11:12
you know, a century time scale by the land in Ocean 6 that's
11:15
built into all of our climate models and, and these scenarios.
11:18
But what that means is that the amount of CO2 in the atmosphere
11:21
doesn't stay constant. It decreases over time if our
11:24
emissions get low enough and if they get to 0 at least up to a
11:27
point, right, Eventually for a particular pulse of emissions,
11:31
the land in the ocean suck up all they can.
11:33
And that last 40% takes, you know, 10s of thousands or even
11:37
hundreds of thousands of years to fully remove.
11:39
But a decent amount happens quickly.
11:40
And because of that, if you actually get to net 0 emissions,
11:44
which is the target that, you know, we've set for ourselves
11:46
globally, then atmospheric CO2 declines.
11:51
Now, that by itself would actually cool the planet.
11:54
However, as we recall from, you know, holding CO2 concentrations
11:58
constant, there's this warming in the pipeline as the Earth
12:01
gets closer to equilibrium as the ocean, which absorbs 90% of
12:04
our heat today, continues to warm up.
12:06
And it turns out, somewhat conveniently, that the warming
12:09
in the pipeline and the cooling from falling atmospheric CO2 at
12:12
net 0 roughly cancel each other out.
12:15
And so in most models, you end up with pretty flat warming
12:19
after you get to net 0 emissions, which is good news,
12:21
right? It means that there's not
12:23
necessarily a lot of future warming.
12:25
But, and this is the bad news, it also means the planet doesn't
12:28
cool itself down for, you know, many centuries, if not millennia
12:32
to come because the oceans are continuing to absorb heat.
12:35
So just getting to net 0 emissions is not going to
12:38
reverse global warming. To do that, emissions have to go
12:41
negative. I mean, I'm not too fussed about
12:42
what happens in centuries and millennia to come because I'm
12:45
sure that's someone else's problem, but at least in the
12:48
short term, we are already approaching, well, we're beyond.
12:54
Are we actually definitively beyond 1.5 as we said, having
12:57
this conversation today or not? What's your?
12:59
View. So our best estimate is that as
13:03
of 2025, the world was at roughly 1.4°.
13:07
We had an individual year 2024 that passed 1.5°, but that was
13:12
driven in part by a strong El Nino event that contributed, you
13:16
know, a bit more than 1/10 of degrees C to global
13:18
temperatures. So our our sort of expectation,
13:20
if you remove natural variability due to El Nino and
13:23
La Nina cycles, is that the world should be about 1.4° above
13:27
pindristoral level due to human activities today, which still is
13:30
really close, right. If the world is warming at, you
13:34
know, .27 C per decade, that means, you know, we have a
13:40
couple years, maybe three years or four years before we get to
13:45
1.5° firmly. Well, in a couple more decades
13:48
and we'll be at 2:00. Degrees, if we don't, you know,
13:52
cut emissions pretty significantly.
13:54
You know, that .27 C per decade is roughly what we get with
13:58
emissions being flattish today and aerosols being cut.
14:01
You know, if we reduce emissions, the rate of warming
14:03
slows down. If we increase emissions, it
14:06
speeds up. And so it's sort of up to us.
14:09
Yeah, I mean, it seems like cutting aerosols from shipping
14:13
is sort of the dumbest air pollution control measure ever.
14:16
Did they not think through the impact this would have on global
14:20
warming? Was it?
14:21
Was that just not considered at all?
14:23
Well, to be clear, it's not just shipping, right?
14:24
Shipping is one part, an important part, but certainly
14:29
not the biggest part of the cooling from these aerosol
14:31
emissions. You know, shipping itself is
14:33
something like 10% of global sulfur emissions.
14:36
It has a bit of an outsized impact on the climate because
14:38
it's happening in in regions with less background pollution.
14:41
So maybe say 20% of the cooling from aerosols is coming from
14:45
shipping. The other 80% is, is other
14:47
sulfur emissions, which are primarily associated with
14:49
burning fossil fuels, particularly coal, diesel fuels
14:53
that have higher sulfur content, things like that.
14:55
I mean, shipping is from burning fossil fuels too.
14:57
It's bunker fuel burned in the ships.
14:59
And so part of the big unmasking we've seen of, of aerosol
15:02
cooling is shipping. The part is also what's been
15:05
happening in China. So China has reduced its sulfur
15:09
dioxide emissions by 75% in the last 15 years, which is a huge
15:14
change. You know, 75% reduction is, you
15:17
know, in some ways as rapid or more rapid than we saw in the US
15:20
after the passage of the Clean Air Act here.
15:22
And so that itself has, you know, probably contributed as
15:25
much to recent warming as the shipping reductions.
15:29
And it's not because they're not burning coal, it's because
15:31
they've put fluid desulfurization technology on
15:33
their coal-fired power stations, right?
15:35
Exactly. And, and the reason they're
15:36
doing it, of course, is because, you know, outdoor air pollution
15:39
is killing millions of people a year.
15:40
And that outdoor air pollution, the particular matter of of 2.5
15:43
microns is largely driven by emissions of sulfur dioxide and
15:47
nitrous oxide. You know, these are precursors
15:49
to, you know, the, the, the same aerosols that are suspended in
15:52
the air that are reflective are also not great things to breathe
15:55
into our lungs. And so the impetus for these
15:57
cleaner regulations is, is public health and even the
15:59
shipping stuff, you know, there was estimates of upwards of, you
16:03
know, you know, 200, three, 100,000 people here are dying
16:05
prematurely associated with port pollution from these ships.
16:08
So I don't think there's necessarily like there's not a
16:13
world where we want to purposefully increase ground
16:16
level air pollution as a way to cool the planet.
16:19
You know, it's, it's a particularly ineffective way of
16:22
doing that because the pollution is so short lived.
16:24
It all falls out in a week or two.
16:25
And it's one that has enormous public health costs, you know,
16:28
if you wanted to get cooling from sulfur.
16:32
And again, you know, this is getting into a little bit of
16:34
controversial territory. You.
16:36
Get something you're about to say.
16:37
Put it in the stratosphere, aren't you?
16:38
Well. You get something like 50 times
16:40
the the cooling effect per ton of sulfur in the upper
16:42
atmosphere compared to the lower atmosphere.
16:44
I don't personally think that it's a slippery slope to do
16:47
anything that purposefully cools the planet like this, But if you
16:50
were to just try try to decide between purposely putting sulfur
16:53
back in shipping fuels or purposefully putting sulfur
16:56
somewhere else in the system, there are ones that give you a
16:59
much bigger cooling effect with a much smaller human health
17:01
impact than shipping. Yeah, I want to get into a whole
17:05
debate debate about that. I do.
17:07
I do actually want to get a hold face about that because I think
17:09
it's a really important issue to talk about.
17:11
But just before we leave the the aerosol shipping pollution
17:14
controls thing, Mindy, as you say, the death toll significant.
17:17
I looked at our world and data and it's what 3-4 some something
17:20
million deaths per year statistically from, from this.
17:23
So of course it's essential to do it because that's a high
17:26
death toll and from climate damages I imagine by any, any,
17:29
any stretch. So it's it's critical, but at
17:31
least. Short term you're comparing, you
17:33
know, climate change integrates over very long periods of time.
17:36
You know, the sulfur pollution is very short lived.
17:38
So it's, it's sort of a little bit of apples Darren, just to
17:40
compare it. So certainly to date, the
17:42
impacts of air pollution have been much more severe than the
17:44
impacts of climate change. Yes, absolutely.
17:47
There are some more outlier type estimates on this though.
17:50
Jim Hansen wrote a great long paper probably last year where
17:54
he estimated that. I'm not sure exactly what the
17:57
exact figure. Probably like several tenths of
17:59
a degree were coming from the removal of aerosols.
18:02
What's your what was your take on his his more pessimistic
18:05
view? So I think he in particular said
18:07
that shipping alone could be up to .2 C additional warming from
18:11
the the shipping pollution reductions.
18:12
So in the last two years there's been eight different papers
18:16
published in the academic literature, most.
18:19
So what you're using, you know, state-of-the-art couple climate
18:21
models that give regional representations of, you know,
18:24
the the effects of aerosol pollution and the background
18:26
state and all these other things.
18:28
Seven of those eight found values that are below .1 C Most
18:31
of them it was somewhere between like 3 hundredths of a degree
18:35
and eight hundredths of a degree was sort of the range in the
18:37
literature. And then Hansen's was, you know,
18:39
3X bigger than any of the other estimates, roughly, or two to
18:43
three X bigger. So it's hard to know for sure.
18:46
You know, aerosols are one of these really tricky parts of the
18:48
climate system and that the process is really complicated
18:51
and there's some disagreement among models and the uncertainty
18:53
is quite large. But I think that Hansen's is is
18:56
very much an outlier among the other published estimates in the
18:58
literature. So I think this is an area where
19:00
we need to do more work, and it's useful to have assessments
19:03
of what the worst case might look like.
19:05
But again, it's also a bit hard to reconcile Hansen's, the
19:07
magnitude of Hansen's estimate with the amount of warming we've
19:10
seen today, right? If that alone was responsible
19:12
for .2 C warming, that seems a bit too much compared to how
19:16
much the world has warmed. And if Hansen is right, then
19:19
we'll see a really big divergent in the next few years compared
19:22
to the historic warming, right? So give it a few more years and
19:25
we'll have an answer. Right.
19:26
Well, I'm glad. Yeah, I'll wait for that.
19:28
Do we understand though what the components of the rapid
19:30
acceleration warming are in that case?
19:32
Is it, is that well enough constrained that you can say,
19:34
well, certain proportion comes from aerosol unmasking, certain
19:37
proportion comes from additional CO2, greenhouse gases, El Nina,
19:40
whatever. Is all of all of those factors
19:42
tied down? South, it's not fully tied down,
19:45
but we have a much better sense of the, the relative
19:47
contributions now than we did, you know, back in 2023 when
19:50
everyone was freaking out about temperature spiking.
19:52
So, so Gavin Schmidt at NASA and I LED a session at the AGU last
19:57
year or the year before last actually on this topic and, and
19:59
published a piece in the WMS state the climate where we sort
20:02
of broke down all the different factors contributing to 2023 and
20:05
2024 exceptional warmth. 2023 is still a little complicated.
20:09
I'll get to that in a second. But 2024, which was the the
20:12
first year above 1.5° in most record.
20:15
A big part of that was El Nino. You know, is, is a fairly strong
20:17
El Nino event, not quite as big as what we saw in in 1998 or
20:20
2016, but enough to add, you know, maybe 1/10 of a degree or
20:25
a bit more to global temperatures .15 C for example.
20:29
Another contributor was the solar cycle.
20:31
So there's a roughly 11 year solar cycle that occurs
20:34
naturally that contributes up to about .1 C between the the
20:38
through and the peak of the solar cycle to global
20:40
temperatures. But it's cyclical so it doesn't
20:42
accumulate, right? It's just up and down, up and
20:44
down. And the most recent solar cycle,
20:46
solar cycle 25 has been a bit stronger than the last three or
20:49
four we've seen. This will contributed a little
20:51
bit more to temperatures. And so we estimate that again,
20:53
you know, maybe 5-7 hundred degree C from the solar cycle.
20:58
Aerosols are part of it. You know, again, estimates vary
21:00
between most of the ones, the literature about 5 hundreds of
21:03
degrees C Hansen's is much higher, but those were a factor.
21:07
And then there is just some year to year variability that's not
21:11
fully forced. And we see this even when we
21:13
account for solar, volcanic factors, all these other things.
21:16
And so if you Add all those up, you can pretty much exactly
21:20
explain what happened to 20/24/2023 is still a little
21:24
weirder. And the reason for that is that
21:27
historically, El Nino has had its main warming impact on
21:32
surface temperatures globally in the year after El Nino
21:35
conditions peak in the tropical Pacific.
21:37
So El Nino conditions usually peak around November or so and
21:42
then it's the year after that, you know, the January March of
21:46
the next year that see the really big spike in global
21:48
temperatures. And so we saw this in 1990,
21:50
seven, 1998, where the El Nino developed in late 19971997 was
21:54
a, you know, a warm year, but not a crazy warm year.
21:56
And the 1998 blew things out of the water, you know, 2015 and
21:59
2016 with the exact same pattern.
22:01
In 2023 though, we saw a much rapid, more rapid warming before
22:06
El Nino fully peaked than we've seen in the past.
22:09
Now, there's been a number of papers published since then that
22:13
suggests that because the El Nino of 2023-2024 occurred after
22:19
a unusual extended period of La Nina activity, there's what we
22:23
call a triple dip La Nina event between 2020 and 2023 where it
22:27
just kept sort of cycling in and out of La Nina conditions.
22:30
That might have primed the system for more rapid warming
22:32
than we typically see during El Nino events.
22:34
It's still a little speculative. You know, Nino is, is hard to
22:38
fully assimilate in models and grasp all the nuances of it.
22:42
But there certainly are a couple periods in the the more distant
22:45
past where we see these very big spikes in temperature.
22:47
There's one of the late 1800s associated with a 2 year old
22:50
Nino. And so there's some suggestion
22:52
that this might be similar to that.
22:55
But I do think there's still some mystery remaining about
22:57
2023 and and again, 2025 was more or less in line with what
23:00
we expected. If you add up the, the various
23:02
factors and, and continued warming, you know, because
23:05
again, here there's still warming every year to, to the
23:08
CO2 and other greenhouse gases. So I personally don't think
23:11
that, you know, once you include aerosols, our best estimate of
23:15
aerosols and, and these other things, there's a huge mystery
23:17
remaining. But there's enough variability
23:21
year to year that it's, it's hard to know for sure at this
23:24
point, which is why I think another few years will, will
23:26
really help answer this question of have we captured the
23:30
magnitude of the aerosol signal? Is it in line with what we
23:33
expect and what models expect, or is there something else going
23:37
on? Could just tell us something
23:38
that the climate is more sensitive than we thought, as
23:40
Hansen argues. And so I think this is just, you
23:42
know, it's a good scientific debate.
23:44
Yeah. And how concerned should we be
23:46
about different tipping points? Obviously this is always for a
23:50
long time has been a big aspect of the climate debate and quite
23:53
rightly so. And it seems to me that it's not
23:57
very well constrained where different tipping points might
24:00
lie. We just don't know at what level
24:03
the Amazon rainforest might collapse, let's say.
24:06
And the typical points to have a feedback effect on the climate
24:08
by releasing a lot more CO2 or methane.
24:11
If it's the melting of Arctic permafrost, perhaps, you know,
24:15
those are the those are almost more concerning than, say, the
24:17
loss of the world's coral reef, which has a huge impact on
24:19
biodiversity but isn't sort of a carbon cycle feedback.
24:23
What do do we know? How much do we know about where
24:26
tipping points might lie in the climate system, and how rapidly
24:29
we might therefore cross them? I might be a little
24:31
controversial in saying this, but I'm not a big fan of the
24:35
idea of tipping points or the framing of things as tipping
24:37
points. And why I say that is I think it
24:39
causes a lot of public confusion.
24:41
You know, when people think about tipping points, they think
24:43
of, you know, what Malcolm Gladwell was referring to in his
24:47
book Tipping Points that like, everything's fine, everything's
24:49
fine, everything's fine. And suddenly, you know, you flip
24:52
a switch and the system falls off a Cliff to a completely new
24:55
state. And there are a handful of
24:58
things in the climate system that might be characterized like
25:01
that. But the vast majority of what
25:02
people call tipping points are really just feedbacks with
25:06
hysteresis. And, and that's a complicated
25:08
technical term, but essentially a, a change that's proportional
25:12
to warming that's hard to reverse that you can't get back
25:14
to if you just undo that warming.
25:15
It would take a lot more cooling to to undo it.
25:17
And so things like permafrost thawing, you know, ice sheets
25:21
loss, even, you know, say what might happen with the Amazon
25:25
rainforest turning into a more Savannah type ecosystem.
25:28
Those are all gradual processes that, you know, don't occur
25:34
every the whole Amazon doesn't suddenly disappear, right?
25:36
You know, regions that have higher rates of deforestation
25:38
that might be, you know, more dry, become more Savannah like
25:41
systems in some parts of the forest but not necessarily
25:44
others. And so the more warming you get,
25:46
the more would convert to that sort of thing.
25:48
Even coral reefs, which are sort of the classic, you know, the
25:52
coral bleaches and dyes or doesn't a tipping point on
25:55
aggregate are still more characterized as, you know,
25:59
temperature dependent. By that I mean that reefs like
26:01
the Great Barrier Reef that are more tropical are more sensitive
26:05
at a particular warming level to bleaching, whereas reefs that
26:07
are more temperate, like in Hawaii, for example, to have a
26:10
bigger difference between summer and winter.
26:11
Sea surface temperatures are more resilient to warming.
26:14
And so even coral reefs are going to see some die at 1.5°
26:18
and some not necessarily die until we get closer to 2°.
26:22
Permafrost is, yeah, similar. Well, what about the, the
26:25
Atlantic current, the the Gulf Stream or the a mark?
26:28
I can't remember what that stands for, but you you can tell
26:30
us. But is is that a classic tipping
26:32
point? We don't think it is.
26:34
So. The AMOK stands for Atlantic
26:36
meridional overturning circulation.
26:38
And most climate models expect a gradual weakening of the amok
26:43
with warming over the course of the 21st century, but not
26:47
necessarily a rapid shutdown. And the the mechanism here is,
26:50
as you know, Greenland in particular starts melting more
26:53
and more freshwater pours into the North Atlantic.
26:55
That slows down the thermal healing circulation that's
26:58
driven by, you know, evaporation of, of water creating more salty
27:02
water in the surface. Salty water is denser, it sinks
27:04
down. That sort of drives it
27:05
comparable to the ocean. So if you add a bunch of fresh
27:07
water to that system, the water gets less salty at the surface,
27:10
it's less dense, it doesn't sink anymore.
27:11
There are some periods in the more distant past, you know, at
27:14
the end of the last Ice Age, for example, where we think there
27:16
was a, a, a rapid shutdown of the thermohalene.
27:18
But that occurred because a, you know, continent sized lake
27:21
leftover by retreating ice sheets, all drained into the
27:24
North Atlantic at once. In this particular case, you
27:26
know, Greenland high sheet loss is rapid by by any standards,
27:31
you know, historically and in the paleo climate, but it's not
27:34
a dam burst and you know, a lake of freshwater gets poured or an
27:38
ocean of freshwater gets poured into the North Atlantic.
27:40
It's it's a process that increases over time.
27:42
That being said, there's certainly some models, most of
27:45
them not pure climate models, but more empirical models that
27:48
do suggest it could be a bit more nonlinear in its dynamics.
27:52
So I don't want to say it can't be, but I think that it's it's
27:55
not necessarily a clear cut, you know, all or nothing type
27:58
tipping point. And I interrupted you when you
28:00
were explaining about Arctic permafrost, so finish that
28:02
thought. Yeah, Arctic permafrost, I think
28:04
of all the sort of tipping points, is the most clearly
28:07
feedback 1. You know, if you think about how
28:10
permafrost thaws, you know, there is a huge range of
28:13
temperatures across the Arctic. It's much cooler at the North
28:16
Pole than it is in in city, northern Canada or even mid
28:18
Canada. The Arctic Circle, Canada state,
28:20
the Arctic Circle starts halfway through the country.
28:23
And so the lower latitude permafrost is going to thaw
28:25
before the higher latitude permafrost S facing surfaces are
28:29
going to thaw before an earth facing surfaces because they get
28:31
more sunlight. And so with every additional
28:34
incremental forming, you get greater amounts of permafrost
28:36
thaw and potentially nonlinearly, right.
28:38
You know, we expect much more rapid increase in thought at say
28:43
3° and we'd see at 2°. But it still ends up being a
28:47
emission response to warming that is modelable proportionate
28:51
to warming. It's it's not a process that
28:52
like runs away with itself. There's not a world where
28:55
permafrost warming creates so much additional emissions that
28:59
it drives more warming that causes more emissions.
29:01
You know, it's, it's sort of on top of whatever else is
29:04
happening. And, and so that is something
29:06
that is broadly included in our models today.
29:08
You know, and, and we have these sort of nonlinear relationships
29:11
between temperature and permopus thaw included in the emission
29:14
scenarios that drive the IPCC models.
29:17
We might get it wrong. You know, it's, we don't
29:19
actually know how quickly it's going to happen because we can
29:22
model it, but we don't have a, a separate planet to run
29:24
experiments on. And so I think that does add
29:27
uncertainty and how much warming is going to happen in the
29:28
future. But I think that's less of a
29:31
tipping point, more of a feedback response to the warm
29:34
you've experienced. We we just classified as a
29:36
tipping point because it would take an enormous amount of time
29:39
and cooling to reform that permafrost.
29:41
You can't put the genie back in the bottle, so to speak.
29:43
What what about albedo type tipping point?
29:45
So if you lose the whole of the Arctic Ocean's cover of sea ice
29:50
in the summer, then you don't reflect all of the sunlight and
29:54
it gets absorbed by the ocean. How how significant is that?
29:56
And, and also maybe cloud disappearances.
29:59
There was, I remember there was a study these very low stratus
30:03
cloud, marine cloud sheets or something and they could not,
30:06
not disappear, but reduce a lot certain warming levels and so
30:10
on. I mean, is any of that worth
30:11
worth a significant account of the deprivation of night time
30:15
sleep? I mean it, it, it certainly is
30:17
important. You know, broadly we expect
30:19
declines in snow and ice cover to contribute to more warming.
30:21
We're already seeing that in in some sort of southern more
30:23
regions of the Arctic where there has been a consistent loss
30:26
of of sea ice in a summer months and even winter months.
30:29
And in some regions, we've seen much or pretty big increases in
30:33
in effective sea surface temperature associated with
30:35
that. And certainly areas like boreal
30:37
forests where we see reductions in snow cover, you know, snow is
30:40
very reflective. And so less snow, darker tree
30:43
surfaces being revealed leads to more absorption of heat that is
30:48
broadly in our models today. So it's not sort of a, an
30:50
unexpected thing. In terms of Arctic sea ice loss
30:54
more broadly, there is no world in the 21st century at least we
30:59
lose winter sea ice. And so even if we lose summer
31:02
sea ice, the ocean is absorbing more heat because it's not
31:05
reflective anymore. You know, that heat is mostly
31:09
going away in the winter when sea ice regrows in, in the
31:13
northern world latitudes, you, you, you are going to have
31:15
increasing loss in the southern parts of the Arctic where sea
31:19
ice doesn't always grow in the winter as temperatures increase.
31:22
But I think where you really start to get.
31:24
Lost sorry when I am trying to get exactly a crucial point, but
31:27
you said the sea ice gets what the heat gets lost.
31:30
Does it get radiated back out to space in the winter or something
31:33
like it just disappears from, well, you're?
31:35
Reforming ice there so you're bouncing, you know, sunlight
31:38
back to space in the winter. It's not being absorbed again.
31:40
It is still going into the deeper oceans.
31:42
You know, the heat that's absorbed in the summer still
31:44
goes somewhere, right? It does have an effect on global
31:47
temperatures, but nowhere near as big if as if you know the
31:50
Arctic was ice for a year round. Right.
31:52
And carry on where I let my interrupted you for a second
31:54
time. Sorry.
31:54
I don't want to minimize this, right?
31:56
You know, these processes all do involve positive feedbacks in
31:59
the climate system. They are all contributing to
32:01
additional warming. You know, you get something
32:03
like, I don't recall the number exactly.
32:05
We had a big review paper we published a couple years ago on
32:08
tipping points, but I think it's something like 1/10 of a degree
32:10
C increase in 2100 temperatures associated with, you know,
32:15
albedo changes in the Arctic more broadly and, and, and snow
32:18
covered regions. So it's, it's an important
32:20
factor. You know, I, I don't want to
32:21
minimize it, but it's not a, you know, sudden dramatic change.
32:26
The cloud cover 1 is interesting.
32:28
It's one where that's probably on the more speculative side of
32:32
of the mechanisms I've been talking about.
32:34
But there have been some high resolution climate modeling work
32:36
done by Tapio Schneider down at Caltech, for example, that shows
32:39
that if you get to really high CO2 concentrations, we're
32:42
talking like 1200 parts per million here, you could have
32:45
rapid stratocumulus cloud deck evaporation.
32:47
These are the low lying clouds that cover much of the oceans
32:50
and, and coastal regions in particular.
32:52
And so in in his models at least, those start disappearing
32:55
very quickly and, and you end up with, you know, an additional
32:58
like 4° warming globally. And over the course of a few
33:00
decades, that would be the the most clear cut example of a
33:03
global sort of Gladwellian tipping point, you know, where
33:06
you have a sudden state change. The good news, though, is that
33:09
at least in his modeling, that only happens at very, very high
33:13
CO2 concentrations. So it might help explain some of
33:15
these previous periods. And there's history like the
33:17
Emian, where the Earth is in some ways warmer than we'd
33:21
expect given the amount of CO2. But it doesn't seem like a
33:23
particularly likely thing to happen in the next century or
33:26
two. And other scientists are a bit
33:28
more skeptical about that mechanism.
33:30
So we don't know watch the space.
33:32
I mean, I think this kind of comes back to my, the way I
33:35
broadly think about tipping points, which is that we have an
33:38
analog 120,000 years ago of, you know, a climate that was about
33:42
as warm as today during the last interglacial.
33:45
You know, it's a bit warmer than most the Holocene, maybe degree
33:47
or two. So comparable to what what we're
33:49
at right now. And we didn't see big runaway
33:52
changes in the climate system at that point.
33:54
But once we push past that, once we get above, you know, 2°
33:58
warming or so, we're going back to a climate that the Earth
34:01
hasn't experienced for, you know, 3,000,000 years or so.
34:04
And the more we push that up, the more there might be climate
34:09
Dragons, you know, the more we're getting into the world of
34:11
unknown unknowns. Because we do know that if you
34:13
go further back in, in time, you know, 10s of millions, 20
34:17
million years, there are some periods of the paleo Theo suit
34:21
thermal maximum is a good example where there's these
34:23
very, very big changes in the climate that happened relatively
34:26
quickly over, you know, millennial time scales, which by
34:28
geologic time is, is a blink of the eye that we don't have good
34:32
explanations for. And so we don't really want to
34:34
run that experiment if we can avoid it.
34:36
Well, it might be methane hydrates or something truly
34:38
scary. Are there any tipping points
34:40
I've not mentioned which we should be lying awake at night
34:43
worrying about? Or is that does that more or
34:44
less cover that? I mean, I do think there's a lot
34:46
of important regional effects and regional tipping points that
34:50
may not have a big impact on global mean surface temperature,
34:53
but could have a really big impact on most people rely on,
34:56
you know, the Amazon, it's one we talked about.
34:58
You know, even coral reefs have a big impact on fisheries.
35:00
You know, there's a lot of of ecosystems that themselves are
35:03
very temperature sensitive or, or species that live in
35:05
particular ecological niches. You know, those are regional
35:08
effects that are global, but they're still important.
35:10
And then the other global one that is probably worth
35:12
mentioning here is ice sheets, because again, ice sheets
35:16
experience a lot of hysteresis and there are potential
35:18
nonlinear loss patterns in ice sheets.
35:21
You know, you, you end up with loss of buttressing sort of ice
35:27
that leads to glaciers flowing much faster.
35:29
You know, you could pass a point at which the collapse of a
35:32
particular ice sheet, you know, not not a Greenland size ice
35:35
sheet, but a, a part of an ice sheet, you know, like you see in
35:37
parts of Antarctica becomes inevitable at a current warming
35:40
level. It's still going to take
35:41
centuries for it to result in, you know, very large amounts of
35:46
civil rise. But we could be in a world
35:47
where, you know, temperatures have increased by two degrees,
35:50
and we're committed to the loss of the 20 Thwaites glacier or
35:54
some of these other big ice shelves in Antarctica that could
35:57
themselves contribute to, you know, meters of civil rise over
36:00
the next few centuries. Yeah.
36:01
So I want to rewind a bit and take us back to the conversation
36:04
that we almost got got got started with on the issue of
36:10
pollution control and the obvious thing to do.
36:14
And you propose this yourself with, I think it was David
36:16
Keith, wasn't it? And the New York Times last
36:19
September is, I don't think you weren't as far as actually
36:22
proposing it, but you sort of you, you posited as a thought
36:25
experiment that why don't we maybe move the at least a
36:28
portion of the sulfate aerosols that people are breathing in
36:31
the, in the troposphere. So in the air that we actually
36:33
breathe where the weather is, why don't we take them and put
36:36
them in the stratosphere where there'd be a lot longer lived
36:38
and they'd still have the same cooling effect.
36:40
And that's known as SRM solar radiation management.
36:43
And I've covered this with different guests in the podcast,
36:45
but I wanted to to talk to you about it because you've probably
36:48
gone further than the most climate experts in putting this
36:52
forward. What was the response to that
36:55
New York Times piece and where do you see the conversation
36:58
going with SRM? So to be clear, we, the New York
37:01
Times piece was trying to take a nuanced position.
37:03
It wasn't necessarily saying that this is something that we
37:05
should do, but was saying that if we end up in a world where
37:09
climate impacts get bad enough that countries do decide to go
37:13
down this path, it's really important to strictly limit it.
37:16
And the reason for that is because, and, and I see people
37:19
get this wrong all the time, you know, solar radiation management
37:23
or any sort of geoengineering of, of, of the shape doesn't
37:29
actually solve the underlying problem of climate change.
37:32
You know, if you go back to Al Gore's an Inconvenient Truth,
37:36
you know, back in 2006, he had this great skit from Futurama,
37:40
the, the classic sci-fi show where they're talking about
37:43
climate change and they come up with a solution, which is to
37:45
drop a bigger and bigger ice cube in the ocean every year,
37:47
thus solving the problem once and for all.
37:49
And all of these geoengineering approaches we're talking about
37:51
marine cloud brightening, sulfate aerosol injection,
37:54
etcetera, are literally that, right?
37:56
You're putting a bigger and bigger amount of sulfur in the
37:58
atmosphere every year, thus solving the problem once and for
38:01
all. And because, as I mentioned
38:04
earlier, the warming of CO2 in particular is so long lived, the
38:09
only way to solve the problem by geoengineering is to keep doing
38:13
it for a thousands of years. And if you ever stop doing it,
38:17
you know, within a couple years, you have this enormous spike of
38:21
temperatures back to pretty much where it would be if you never
38:23
started doing it in the first place.
38:25
And so once you go down that path, particularly once you
38:27
start masking significant amounts of warming with
38:30
geoengineering, you're really committing future many, many,
38:34
many future generations, you know, 10s of future generations
38:37
to this path of global scale interventions that I think are
38:40
problematic. And the only way again, to to
38:43
stop that without waiting thousands of years is to suck up
38:46
all the carbon that you've added to the atmosphere since you
38:48
started doing it. And that itself ends up being
38:50
enormously expensive, you know, at $100 a ton of, of carbon
38:54
removal, which is, you know, something that the, we all hope
38:57
to get to 1 day, it's like 500 today, you end up spending about
39:00
$22 trillion to cool the planet, 1/10 of a degree C.
39:03
So to put that another way, every 10th of a degree C you're
39:07
masking with geoengineering is a $22 trillion debt you're passing
39:10
down to future generations if they ever want to stop doing it.
39:13
And so for that reason, you know, we were making the case
39:15
that if we do go down this path and there could be a world where
39:18
the impacts of climate change get bad enough that we need a
39:21
stopgap, we need to break glass in case of emergency option.
39:24
But if we do do that, we should put some strict limits on how
39:27
much we do because it does become easy to justify, you
39:33
know, minimizing costs for people alive today by punting
39:36
the can down the road and putting those costs in future
39:39
generations. Maybe, but the future
39:41
generations will have presumably higher like standards of living
39:46
and more technological options to to deal with it.
39:49
And they may have got Cdr technologies down to a, a more,
39:53
a more manageable level in terms of their cost.
39:55
But so let me put a modest proposal to you.
39:58
How about we all just sit there and say, right, we're not going
40:01
to allow the planet to go over to let's say 2.5°.
40:04
That's intolerable. I mean, obviously the Paris
40:06
limits were 1.5 and 2°. But didn't we say, right, we, we
40:11
should deploy full scale solar radiation management at 2.5?
40:15
We should. Get deployment ready at 2:00 and
40:18
we should be doing significant field work and research where we
40:21
are currently today at 1.5. What?
40:23
What would you say to that? I think setting a specific
40:26
temperature level is premature, I think because we don't really
40:30
know what the impacts of climate change are going to be at 2.5°.
40:33
Like we, we can model it, sure, but you know, the, the real
40:37
world is complicated. The impacts on all the different
40:39
human and natural systems are really complicated.
40:40
And, and we've learned, you know, just in the last few
40:42
decades that some of the impacts that we thought would be small
40:45
under say 1.5° or, or bigger than we initially expected.
40:48
So I'm a little cautious about setting a particular level.
40:52
But that being said, you know, I, I do support research on how
40:57
it works. You know, I think that we should
41:00
think about a world where we might have to use it.
41:03
I think what I worry about is this issue of moral hazard
41:07
again, because you could spend, I don't know, $10 billion a year
41:10
to do an equivalent of a pinotubo of solar radiation
41:13
management, you know, say half a degree C cooling.
41:16
Just just rewind and tell people what a Pinotubo is.
41:19
And also, and you said it's actually so, and this is really
41:22
critical, critically important as well, is that it doesn't cost
41:25
very much when you fly a fleet of planes in the stratosphere
41:27
and you release a bit of sulfur, I mean, that costs billions
41:29
rather than the 10s of trillions that you're talking about
41:32
before. So yes, back to the Pinatubo.
41:34
So Pinatubo was the biggest volcanic eruption in recent
41:37
history in terms of its climate effects.
41:39
It was big volcano that dropped in 1992.
41:41
It put. I'm trying to remember the exact
41:44
number, I think in the order of. A lot, 50 million tons or
41:48
something, I don't know. It was, it was a yeah, I don't
41:51
want to make, I think 50 is just 50.
41:53
I think is a little high, but 50 is roughly what humans are
41:56
emitting today to to the lower atmosphere.
41:57
But to say 15,000,000 tons of of sulfur dioxide into the upper
42:01
atmosphere, which lasted for a couple of years and you know
42:04
before dissipating and and caused some temporary cooling.
42:06
It was temporary again because it was a one time eruption and
42:09
then the sulfur fell out of the upper atmosphere, eventually
42:12
settled back down on the surface.
42:14
You could do an equivalent of that every single year for not
42:18
an enormous amount of money. And so again, the problem with
42:22
that thinking though, is that you then have to do it again the
42:24
next year and again the next year, again the next year
42:27
forever. And if you Add all that up, it
42:29
does become an enormous amount of money.
42:30
And so there there is this tendency to, you know,
42:35
particularly in a world where our politics and our business
42:40
decisions and everything heavily discounts the future and is is
42:42
very short term focused that it will be a good fit for as as a
42:49
as that sort of solution, but then sort of stick us in this
42:51
massive of having to clean it up in the future.
42:54
It certainly is arguably better than a world where we do nothing
42:57
about climate change and everyone suffers.
42:59
But I worry that by embracing it as a solution, it might, at
43:03
least in some quarters, reduce the impetus to to actually
43:06
reduce emissions and deal with the underlying problem.
43:09
Yeah, I mean, I'm just attracted to the idea because I wrote a
43:12
book called 6° and everything above 3 was frankly terrifying
43:17
and got more and more apocalyptic as you've got higher
43:19
up. And we could, with SRM,
43:21
literally just sit here and say we're never going to see any of
43:23
that. We have the the technology isn't
43:25
that difficult. Yeah, though though it is worth
43:28
mentioning that there are side effects, particularly as you
43:30
start getting more and more SRAM, right?
43:32
You know, the what we're doing is sulfur dioxide in lower
43:34
atmosphere today, half a degree C or so of cooling.
43:37
You could do that in the upper atmosphere likely without huge
43:40
effects. But once you start getting much
43:42
above that, once you start talking about a degree of
43:44
cooling or, you know, 2° of cooling, suddenly you're
43:47
starting to have pretty negative effects on the ozone layer.
43:50
You're impacting crop growth because again, you're scattering
43:52
a bunch of sunlight that would otherwise hit the surface.
43:54
The whole world becomes dimmer at really high levels.
43:57
You turn the sky white. You know, it ends up becoming a
44:01
little dystopian by itself. So it's so I do think we should
44:03
account for the impacts of it as well, which is again, still
44:07
probably then much lower impact than the impacts of climate
44:11
change at those warming levels. But we also don't know, we
44:13
haven't run these experiments. The only analogs we have are
44:16
volcanic eruptions, but those are very short lived.
44:18
You know, we haven't really experienced a period of
44:21
sustained volcanic aerosol injections over decadal time
44:24
scales, you know, at least since the mid 1800s or early 1800s.
44:30
But how, how about we use it just to cut the top off the
44:32
overshoot graph then? So it's going to take time to
44:36
transition to net 0, but I think we're we're already headed in
44:40
that direction. You can see the rapid uptake of.
44:43
So, so if I were the, you know, the ruler of the world and could
44:47
decide exactly what the optimal path is for everyone to reduce
44:50
emissions and, and deal with overshoot and deploy large
44:52
amounts of Cdr, like I, I think I would have very little
44:58
reluctance to, to shave off that peak with, with SRM, right?
45:01
You know, you're minimizing suffering.
45:03
You're not changing the overall trajectory of, of mitigation or
45:06
carbon removal. You know, you're just taking
45:08
what would be a period of around 2° and keeping things at 1.5°
45:12
until we, we suck out enough carbon to actually bring
45:15
temperatures back down to that level without the SRM.
45:17
And then you stop doing the SRM, everything is great.
45:20
The challenges, of course, that we don't live in that, you know,
45:23
optimally utilitarian world. In reality, you know, there's a
45:27
bunch of different factors that drive the actual levels of
45:29
mitigation that we have. And again, what I, what I worry
45:31
more about is a world where SRM becomes a crutch that reduces
45:35
the impetus for mitigation. And then suddenly we're relying
45:37
on it more and more and more and more every year, and it becomes
45:39
too expensive to ever stop doing.
45:42
But I don't think we're doing mitigation for the sake of the
45:44
climate anyway. I mean, we're now at the stage
45:46
where it's, yeah, but I think it's cheaper to put in solar and
45:51
batteries than fossil fuels in a lot of the developing world now.
45:54
And that process is only going to accelerate.
45:56
So you've got a kind of technological tipping point
45:59
which is possibly pushing the economics now in the right
46:02
direction that we will eventually get to at least
46:04
towards a lot closer to net zero in a space of two or three
46:08
decades potentially. But we can't separate that
46:11
technological tipping point from the underlying policy drivers,
46:16
right? You know, the reason why solar
46:19
became cheap was a huge amount of federal investments in the US
46:22
in the 70s. You know, Germany spending what
46:25
it was, to be honest, a stupid amount of money subsidizing it
46:28
in a place that's not great for solar.
46:29
But getting those economies of scale, China deciding to go big
46:32
on it, you know, in part because of concerns about climate
46:35
change, but also because they thought other people would be
46:38
concerned about air pollution and climate change, these other
46:41
things and want to buy large scale clean energy.
46:43
And you know, as that happens, realizing that it might get so
46:47
low cost, it would just went out on the merits purely.
46:49
So, you know, I, I think that technology and, and policy are
46:53
inherently entertained in a lot of ways.
46:55
And the driver of technological declines over time is impart
47:02
these policy decisions that folks have made.
47:04
And you mentioned carbon removal a few times.
47:06
Can we look at some of the options here?
47:08
Because I know this is something you focus on at a strike, right?
47:10
Well, what are what are the most promising options and how much
47:14
do they look like they're going to cost?
47:16
So when I think about carbon removal, I sort of break it into
47:20
two categories. And again, here I'm talking
47:22
about the more durable stuff, because if we're talking about,
47:25
you know, the lifetime of, of CO2 warming in the atmosphere,
47:27
you can't just suck it up for a decade and put it back in.
47:30
It doesn't actually it, it cools things temporarily, but it
47:32
doesn't actually do that much. And in fact, temporary carbon
47:34
removal is conceptually actually quite similar to geoengineering,
47:38
right? You're you're not solving the
47:40
underlying problem. But if you look at the more.
47:42
Sorry, what's temporary carbon? I'm like what?
47:44
It's not like planting some trees that then get burned in 10
47:46
years or something or what. Yeah.
47:47
So temporary carbon removal will be like soil carbon work that
47:50
requires active management to keep there.
47:53
That is probably not going to happen forever or you know,
47:56
planting trees in areas that are fire prone.
47:58
You know, like California's seen its hundred year buffer pool for
48:02
its carbon forestry projects all burned through in the last
48:04
decade, things like that. That's not to say that all
48:07
biosphere carbon storage is impermanent, right?
48:09
You could in theory, you know, protect forests over the long
48:13
term. It's just hard to guarantee.
48:15
Methane abatement is actually another sort of temporary thing.
48:18
But but on the durable side, you know, the, the essentially
48:21
taking carbon and, and turning it back into coal or otherwise
48:25
carbonate, fossilizing it, carbonating it or injecting it
48:28
into geologic storage. There's sort of two categories
48:32
that I like to think of Cdr. There's the stuff that is
48:35
probably cheaper near term, but limited, you know, because of of
48:40
various reasons. I'll get to them in a second.
48:41
And then there's the stuff that's more expensive today, but
48:44
could potentially grow to, you know, 10s of billions of tons
48:48
per year scale. So I'll start with the the first
48:50
category, the stuff that is relatively relatively cheap,
48:53
it's still expensive today, but probably has limits to scale.
48:57
And those include biomass based carbon removal approaches.
49:00
So, you know, most expensive part of carbon removal is
49:04
getting the carbon and nature turns out to be pretty good at
49:08
taking carbon out of the air and and fixing it into a biomass.
49:11
The problem with that is that you don't want to take biomass
49:15
that would otherwise be storing that carbon and just stick it
49:17
underground, because then you're just moving the carbon from one
49:20
place to another. You're not permanently you're,
49:22
you're not necessarily, you know, you don't want to cut down
49:25
forests to do carbon removal and so, or you don't want to
49:29
displace food production because then, you know, people are
49:31
suddenly cutting down the rainforest to grow more, you
49:33
know, soybeans because you're using US firm land for energy
49:36
crops, as we've seen with corn ethanol.
49:38
Like there, there's a lot of reasons why once you start doing
49:40
dedicated biomass growing for, for biofuels or carbon removal,
49:45
it, it messes up the math. So if we limit the world of
49:48
carbon removal to waste and residue biomass, the stuff that
49:52
doesn't necessarily have a valuable use today and would
49:55
otherwise be rapidly released to the atmosphere through
49:57
decomposition, you're talking about forestry residues, things
50:00
like, you know, sawdust or you know, emissions from pulp and
50:03
paper plants of biogenic CO2 from black liquor or crop
50:08
residues like corn stover or rice husks.
50:11
You're talking about manures, human wastes.
50:14
You know, there's a a couple billion tons per year of waste
50:17
and residue biomass that you could potentially turn into
50:20
carbon move well, either through burning it for bioenergy and
50:22
capturing the carbon from that or through directly injecting
50:25
the biomass into geologic storage like vaulted deep is
50:28
doing. They're injecting a human bio
50:30
solids that are P fast contaminated into geologic
50:32
formations that would otherwise be incinerated.
50:35
There's a whole slew of different ways to take do carbon
50:37
move with biomass, but they are fundamentally limited by the
50:39
amount of of available waste and rescue biomass.
50:43
So that's one that's probably the cheapest option today,
50:45
coming in at around $200 a ton. If you're talking about like
50:49
retrofitting a big European bioenergy plant with CCS, for
50:52
example, 202 fifty, somewhere in that range.
50:55
Another promising one that again, can scale, but only so
50:59
far is enhanced rock weathering in agricultural fields.
51:01
So over geologic time, the biggest driver of the carbon
51:05
cycle is the balance between volcanic eruptions that emit CO2
51:10
and the weathering of volcanic rocks like basalt or olivine
51:14
that absorbs CO2. So essentially the volcano
51:16
liberates the carbon from the rock and then as the magma
51:21
releases, eventually breaks down and weather is in the rocks
51:24
weather, they reabsorb that carbon the the volcano emitted.
51:28
And so naturally about a billion tons per year of carbon dioxide
51:31
is absorbed by silicate rock weathering.
51:33
And so enhanced rock weathering is a method of speeding up that
51:35
natural process, you know, grinding up the salt to to find
51:39
powder or using waste powders from quarries and spreading it
51:41
on firm land where it breaks down in the acidic soils,
51:44
absorbs CO2, forms bicarbonate, and eventually ends up in the
51:47
ocean. There's probably on the order of
51:50
a billion tons per year of potential of farmland with
51:55
acidic soils. That's close enough to quarries
51:57
where you don't have to transport the rock over long
51:59
distances, which kills the life cycle viability of, of the
52:02
process. There's a bunch of uncertainties
52:04
and the verification of it because it's hard to measure.
52:07
I don't want to get too far into the weeds into that.
52:08
You can listen to a podcast they did with David Roberts on Fox or
52:12
not Box Anymore Volts, where we dive really deeply into this
52:15
particular topic. And, and that's, you know,
52:17
somewhere in the order of 250 to $350.00 a ton today.
52:20
And there's a couple other variations of that, you know,
52:24
putting alkaline rocks into wastewater treatment plants or
52:28
into acidic rivers like carbon run is doing in Canada.
52:31
Those are also in the same price range, also have some limits.
52:35
You know, there's only so many wastewater treatment plants,
52:37
there's only so many acidic rivers.
52:38
You're probably talking about couple 100 million tons,
52:41
probably less than a billion tons for each of those pathways.
52:44
So that's the sort of more limited side, cheaper today, but
52:48
could only scale a certain amount.
52:50
If we go to the other side, the stuff that could be more
52:52
backstop technologies that could really undo a lot of warming,
52:55
you know, half a degree of warming, a degree of warming in
52:57
in a more distant future. There we're talking about 3
53:00
technologies, a director capture, ocean alkalinity
53:03
enhancement and superficial mineralization.
53:06
And I'll start with director capture.
53:07
So director capture is probably the longest standing Cdr
53:12
technology aside from Bax Bio interview with carbon Capture
53:14
and Storage. And if people think of Cdr, they
53:17
probably think of a giant rack of fans at a director capture
53:19
plant. Essentially the idea there is
53:21
you use some sort of solvent or sorbent that binds with CO2 in
53:26
the air and forms and and sucks up that carbon.
53:29
And then you heat up that sorbent to a pretty high
53:31
temperature to release the carbon in a pure stream of CO2
53:35
and sort of recycle it through the system.
53:37
That could be as simple as just using limestone as heirloom
53:39
does. Or you put the limestone out in
53:42
trays, it absorbs CO2 in the air, you throw it in a calciner,
53:44
get a pure stream of CO2 and put the limestone back in the trays
53:47
and just do that over and over again.
53:48
Or much more complicated chemical sorbents and solvents.
53:51
The problem of course is the heating part, right?
53:54
You're heating, you're both moving a lot of air through
53:56
mechanical means in most of these cases and you're then
54:00
heating up the resulting a carbon rich material to get that
54:03
pure stream of CO2. And that takes an enormous
54:05
amount of energy. And so for that reason, director
54:07
capture today is upwards of $500 a ton, you know, could fall, but
54:12
is still probably going to be more than $200 a ton for the
54:14
receivable future and uses an enormous amount of energy at a
54:17
time when we really want to be using clean energy to
54:21
decarbonize the rest of our economy.
54:23
And so there's a concern around competition at together.
54:26
You also need geologic storage of CO2 like old wells you can
54:30
put it in. There's enough of that globally
54:32
for probably at least a trillion and a half tons of storage, but
54:36
you might not always have the, you know, ideal set of
54:39
circumstances where you have low cost clean energy that overlaps
54:42
with geologic storage. The other two technologies, and
54:45
I'll go quickly so I'm going very deep in the weeds here, are
54:47
ocean alkaline enhancement or ocean lining as we call it.
54:50
And there you're essentially taking limestone, which is
54:52
ubiquitous, which has carbon dioxide in it.
54:54
You're heating up that limestone, similar to what you
54:56
do for DAC to release the carbon content of it and injecting that
54:59
in geologic storage and then taking the resulting calcium
55:02
oxide or or magnesium oxide if you use magnesite and putting
55:06
that in the ocean where it rapidly dissolves makes the
55:09
ocean less acidic, which then causes the ocean to absorb RCO
55:12
2. The benefit of that over DAC is
55:14
that by putting in the ocean, you're forming bicarbonate
55:17
instead of carbonate, so you get, well, theoretically up to
55:20
twice as much storage per unit of alkalinity.
55:23
In reality, it's like 1.6 X versus forming carbonate because
55:27
of various lost terms and inefficiencies in in that are
55:30
function of salinity anyway. But the point is that can
55:33
potentially be cheap and and scalable.
55:34
Today, folks are figuring out ways to use industrial waste
55:37
that are alkaline rich as as a cheaper option without having to
55:40
do the sort of purpose creation of of alkaline materials.
55:44
But certainly if you wanted to scale this up to billions of
55:46
tons, you'd have to do something like large scale Cal signers
55:50
with CCS and then, you know, truck it on shifts and dump it
55:54
in here, spread it in the ocean. The final one is what we call
55:57
surficial mineralization. And that's very similar
56:00
conceptually to some of these other pathways taking an
56:02
alkaline rock. But here you're focusing on very
56:05
reactive rocks, things like serpentinites, Christa teals,
56:07
Bruce sites. You quarry them up, off out of
56:10
the ground, you grind them up coarsely or otherwise figure out
56:15
a way to make them accessible to for carbon to bind to.
56:18
You add a little bit of moisture and they form a carbonate.
56:22
Essentially have them naturally absorb CO2 and then you just
56:25
create a big pile of that resulting carbonate somewhere.
56:27
There are trillions of tons of alkaline rocks that you could
56:30
quarry up that are near the surface.
56:31
Could potentially become cheap in the future, but you do end up
56:34
having to deal with these giant piles of carbonated rocks.
56:38
And some of the most reactive substances like crystal teal
56:41
contain things like asbestos, which maybe if it's contained to
56:44
a specific site is fine, but you wouldn't want to like truck it
56:46
around or, you know, use it anywhere where people could be
56:50
exposed to it. You haven't mentioned ocean line
56:53
fertilization, been sort of semi persuaded that survival option
56:58
by growing oceans. I don't know if you've come
57:01
across them, but the, what's really interesting is they, they
57:05
suggest that there's quite a high ratio between the amount of
57:07
iron you put in, the amount of carbon you sequester.
57:10
So some of these, you know, the enhanced rock weathering is
57:12
probably, I don't know, ton ton for ton or something.
57:15
You have to move a lot of material around and grind up a
57:17
lot of material to get a ton of carbon out.
57:18
But with the iron and the ocean stuff, apparently you can put a
57:22
ton of iron in and get, you know, 10s of thousands of tons
57:26
potentially of carbon sequestered by the resulting
57:29
bloom in phytoplankton. If if the the work is to be
57:34
relieved, have you have you looked into that at all?
57:37
I have, so that one is, has much higher scientific uncertainties
57:42
and some of these other pathways and a lot of practical policy
57:47
challenges. And, and some of this comes from
57:48
the unfortunate legacy of a fellow named Russ George, who,
57:52
you know, did a sort of rogue geoengineering experiment to
57:56
dump a bunch of iron off the coast of Galapagos, you know, 2
57:59
decades ago and sort of led to a bunch of this activity being
58:02
formally banned under the London Convention.
58:04
So there there's a pretty big barrier to practically doing
58:06
those experiments today in part because of that.
58:08
There's also bigger questions around the durability.
58:11
So it it, if you add a bunch of iron to the ocean, it will
58:15
create a big bloom of, of phytoplankton.
58:17
You know, that's pretty straightforward in regions that
58:19
are iron deficient, But how much of that actually sinks to the
58:23
deep ocean versus, you know, decays in shallower water and
58:26
releases the CO2 is very much an open question.
58:29
And the effect that has on so the secondary effects that has
58:33
on other phytoplankton growth is also complicated.
58:36
So for example, if you add iron to a region, you trigger a
58:39
bloom, those phytoplankton absorb a bunch of other
58:42
nutrients that are not ironed from the water as part of that
58:44
growth, which then depletes those and potentially could
58:46
inhibit growth that would otherwise occur in other
58:48
regions. And so the the secondary effects
58:50
of these end up being fairly complicated.
58:52
So I'm not trying to say that that's never an option, but it's
58:55
one that isn't being pursued much at scale today, at least
58:59
in, you know, government support and and volunteer carbon
59:02
markets, in part because of the scientific uncertainty and in
59:05
part because of the than SC politics around it.
59:07
So which one is your money on? Because you know, at the
59:11
consensual level, it might be cheaper if you want to
59:14
decarbonize aviation, let's say. And no one's invented an easy
59:18
substitute for jet fuel to remove the carbon elsewhere.
59:20
If it's actually cheaper to do that, then then make some
59:23
incredibly expensive synthetic jet fuel using, you know, some
59:27
sort of carbon source. So like is, are any of these Cdr
59:31
technologies, carbon removal technologies looking promising
59:33
enough that they can actually be kind of cost competitive in a in
59:37
a meaningful way? Yeah.
59:38
I mean, I, I think the biomass based stuff is, is cost
59:41
competitive today with a lot of these other things like it.
59:44
If you're looking to produce sustainable aviation fuel with
59:46
biomass, which most projects doing that today are, it
59:49
actually is in most cases cheaper just to use the same
59:53
biomass for carbon removal and burn jet fuel than to turn that
59:57
biomass into sustainable aviation fuel and burn it, you
1:00:00
know, similar. That's.
1:00:01
The same? That's the same thing, is it?
1:00:03
I'm trying to get my head around this.
1:00:04
Is that the same thing? Aren't you still taking fossil
1:00:07
out of the ground and putting it in the atmosphere or no, because
1:00:10
you're you're removing an equivalent amount of carbon,
1:00:12
aren't you through the biomass? And yeah.
1:00:13
So, so if you have a particular unit of biomass, right, you
1:00:16
could put it in a fermentor to produce some sort of biofuel
1:00:20
that you use for sustainable aviation fuel.
1:00:22
You lose say 60% of the carbon content of the biomass in that
1:00:25
fermentation process. So it's not very efficient.
1:00:28
But then you you're not burning the diesel fuel anymore, you're
1:00:30
just burning the biomass. Or you could take all of the
1:00:35
carbon content that biomass and just inject it underground or,
1:00:38
you know, use it for to produce electricity and capture all the
1:00:41
carbon on the back end through or 90% of it through a CCS
1:00:43
process and burn jet fuel. One way the carbon from the
1:00:47
biomass goes back to the atmosphere, but it's carbon
1:00:49
neutral. Another way the carbon from the
1:00:50
biomass goes into geologic storage.
1:00:52
So it's carbon negative, but fossil carbon is coming out of
1:00:54
the ground. My point is that it's generally
1:00:56
cheaper to do the latter to just capture the carbon content to
1:00:59
the biomass than to turn into something.
1:01:01
There's actually a something called the Ames principle named
1:01:03
after Roger Ames, who's a a senior researcher at Lawrence
1:01:06
live from our labs that essentially says that the carbon
1:01:08
value of biomass will in a future carbon constrained world
1:01:14
be much more valuable than the energy potential of that
1:01:16
biomass. So, but but stepping back a
1:01:19
little bit, the the biomass stuff is pretty cost competitive
1:01:22
today with hard to decarbonize parts of the economy like
1:01:24
aviation. And we're already seeing, you
1:01:27
know, multi billion dollar deals being struck by folks like
1:01:29
Microsoft for biomass based Cdr pathways, you know, big projects
1:01:33
to retrofit. You know, for example, we, we
1:01:36
and Microsoft both are supporting the retrofit of the
1:01:38
big district heating facility in Stockholm, Sweden.
1:01:41
You know, it's a a giant facility that burns all the
1:01:43
residuals of the forest, the Swedish forestry system, all the
1:01:46
like wood chips and branches and stuff that can't be used for
1:01:49
commercial timber goes to this big facility in the middle of
1:01:52
Stockholm, gets burnt, produces heat that get gets pumped into
1:01:56
the district heating system and all the homes and releases all
1:01:58
the CO2 from the biomass. And So what we're doing is just
1:02:00
sticking a carbon capture unit on that existing bio energy
1:02:03
facility and shipping it off to Norway to inject in the Northern
1:02:06
Lights project in the North Sea. So that sort of thing, that's
1:02:09
what was that $1.5 billion project.
1:02:13
Those sort of things, you know, are already pretty cost
1:02:15
competitive today and being developed today at a pretty big
1:02:18
scale. You could Drax as well in the UK
1:02:20
because that's a big biomass plan.
1:02:21
I mean, are there various other ones you could?
1:02:23
Yeah, Drax. Drax has had some historical
1:02:26
challenges around the sustainable sourcing the
1:02:28
biomass, which has led to to folks being a little more
1:02:30
skeptical of funding that one for carbon removal projects.
1:02:32
But there certainly are a bunch of similar things to that,
1:02:34
particularly, you know, because you, you do want to make sure
1:02:36
that, you know, any of these projects, even if it's an
1:02:40
existing facility, are still not causing other ecological harms.
1:02:44
The last thing you know a tech company wants is pictures of the
1:02:47
boreal forest, you know being clear cut associated with their
1:02:50
carbon removal project. But you've got scalability
1:02:52
challenge. If you're just using off cuts in
1:02:54
Sweden, you're not going to get very far to towards
1:02:56
decarbonizing. Well, but that's one of many
1:02:58
examples, right? You know, we're doing a project
1:03:00
in Norway that's taking a municipal solid waste
1:03:02
incineration facility because waste energy is a big thing all
1:03:05
across Europe and putting a capture carbon capture unit on
1:03:07
that. You know, about half of the
1:03:09
waste is fossil carbon, but about half is biogenic carbon.
1:03:12
And so the fossil carbon half gets sold in the UETS, the
1:03:14
biogenic half gets sold to private sector buyers.
1:03:18
And that, you know, is another million tons or half a million
1:03:20
ton project for that. And you could scale out to all
1:03:22
the waste energy plants in Europe and you're suddenly
1:03:24
getting to, you know, high 10s of millions of tons, you know,
1:03:28
pulp and paper in the US, biggest biogenic emitter of CO2
1:03:31
in the entire country, 300 million tons per year just from
1:03:34
pulp and paper mills. There's a company called CO280
1:03:38
that's doing a huge amount of work in retrofitting pulp and
1:03:40
paper mills with post combustion capture from, you know, because
1:03:44
essentially they take all the parts of the tree that aren't
1:03:46
used to print paper and burn it to produce the energy to power
1:03:48
the mill. So there's a lot of biogenic CO2
1:03:51
emissions today that could be captured for a relatively low
1:03:54
cost. Never even knew that.
1:03:55
It's amazing. And, and is the CCS technology
1:03:58
advanced far enough that it's actually viable?
1:04:01
Because I've always been a bit of a skeptic.
1:04:02
There's been talk of CCS carbon capture storage for a long, long
1:04:05
time, billions going into it and then never quite seems to
1:04:08
happen. So where, where, where are we at
1:04:10
with that? So at 200 to $250 a ton, it is
1:04:15
viable. Some of that is storage from
1:04:17
transport costs. So, you know, practically, so
1:04:19
say 150 to $200 a ton, you know, there are operating units for
1:04:25
like Heidelberg Cement for example, that have been
1:04:27
capturing carbon for quite some time at you know, 80 to 90%
1:04:31
efficiency. There's a bunch of companies now
1:04:33
making modular capture units of like 400 or 800,000 tons per
1:04:37
year that are being deployed. So I do think that it will be
1:04:41
nice to see more of these operating over longer periods of
1:04:43
time, but we've started seeing some some promising numbers.
1:04:46
I think one of the challenges historically is that it still
1:04:49
requires a decent amount of energy use.
1:04:51
So for example, you know, if you were retrofitting something like
1:04:54
a coal-fired power plant with that post combustion capture
1:04:56
unit, you end up using something like 15% or 20% of the plants
1:05:00
power output just to power the capture process, which ends up
1:05:03
being pretty prohibitive cost wise, especially for something
1:05:06
like coal which already struggles to be cost competitive
1:05:08
with other fuels. But for some of these industrial
1:05:11
processes where there's not good other options, it it is probably
1:05:16
the cheapest way to to reduce emissions in those sectors.
1:05:19
Like is this your job right? Is this your job at striped then
1:05:21
to just keep across all of this stuff and to make
1:05:24
recommendations to the board? Like, I don't really understand
1:05:26
why financial payments company, if that's what Stripe is, to my,
1:05:29
to my knowledge is, is employing, you know, a climate
1:05:32
scientist. Yeah, so the the Stripe story is
1:05:35
actually kind of an interesting 1.
1:05:36
And so Stripes Co founder and CEO Patrick Collision read
1:05:40
because he's a gracious reader. He read the 2018 IPCC report on
1:05:44
1.5° and when it came out and that report had a huge focus on
1:05:49
carpet removal because if you want to limit warming to 1.5°,
1:05:52
you need a lot of carpet removal.
1:05:54
And when he read it, he was like, well, wait a minute,
1:05:56
everyone says we need this thing that doesn't actually exist in
1:05:59
the real world because, you know, in 2018-2019, it didn't,
1:06:03
there was no carbon removal. And so he thought it would be an
1:06:06
area where a relatively small amount of resources could go a
1:06:09
long way and, and helping kick start what seemed to be an
1:06:12
industry that that would be needed in the future but wasn't
1:06:14
happening today. And so Stripe initially started
1:06:16
a thing where people who sign up to use the payment processing
1:06:19
can opt in to donating, you know, half a percent or 1% of
1:06:22
the revenue they transact to fund the development of
1:06:24
permanent carbon rule technologies.
1:06:26
You know, you know, that raised, you know, $25 million or so a
1:06:30
year going into the early 2000 twenties, but wasn't a big
1:06:35
enough scale by itself to really kick starting industry, right?
1:06:38
You know, 15, twenty $25 million a year is, is not nothing, but
1:06:42
that's, you know, revenue for one small to medium sized
1:06:45
company. And so there is this idea of
1:06:47
like, how do we take what we're doing at this very early stage
1:06:51
and make it a big enough scale that it can actually shape an
1:06:54
industry? And so Patrick called up, you
1:06:57
know, the CEO of Google, the CEO of Meta, McKenzie, JP Morgan,
1:07:03
Salesforce, Shopify, and sort of convinced them all to pool
1:07:07
resources into what we call an advanced market commitment.
1:07:10
And so advanced market commitments or AMC's was an idea
1:07:13
that was originally pioneered in the public health space where
1:07:16
you have a similar chicken and egg problem with vaccines for
1:07:18
tropical diseases like new mem, new Memococcal, where you know,
1:07:23
there's a huge need for it, but there's not a clear market for
1:07:25
it because the people who need it can't afford to pay for it.
1:07:28
And so in the vaccine space, you know, the Clinton Global
1:07:31
Initiative and others had pioneered this idea of putting
1:07:33
together a big pool of money. So new memococcal vaccine I
1:07:35
think was 1.5 billion, where they said, OK, we're going to
1:07:38
put together this pool of money. If you build a vaccine that
1:07:40
works, we will guarantee we're going to spend at least a
1:07:42
billion and 1/2 on it. And that worked really well
1:07:45
because drug companies were like, great, there's a
1:07:46
guaranteed market that de risks. I mean, there's still always a
1:07:50
risk in creative vaccines that may not work, but it, it de
1:07:52
risks a big part of the drug development process for diseases
1:07:56
like this where there's not a clear big consumer demand of, of
1:07:58
people who can afford to pay for it.
1:08:00
And so for carbon removal, there's a very similar problem,
1:08:02
right? You know, carbon removal is
1:08:03
valuable, but no one is willing to pay for it because it's a
1:08:06
public good. And so by putting together, in
1:08:08
our case, a billion dollars into an advanced market commitment
1:08:11
and saying we are going to spend this money by 20-30, that was
1:08:14
enough to create a demand pull for a market.
1:08:16
You know, companies could go to VCs and say, hey, we have an
1:08:19
idea for this carbon removal project.
1:08:20
There's this billion dollar market that we can sell into and
1:08:23
get revenue, you know, fund us. And they did.
1:08:26
And then, you know, folks like Microsoft pulled into the market
1:08:28
and Microsoft now spends a billion dollars on a single
1:08:30
carbon removal contract. You know, they're spending many,
1:08:32
many billions of dollars on this.
1:08:34
And so it's it really has over the last few years become, you
1:08:37
know, not a mature market, but a real market.
1:08:40
And what we really aim to do with to work at Stripe and and
1:08:43
Frontier, which is this coalition of companies is to use
1:08:46
this decade to figure out what works and what can scale.
1:08:48
Because we know we're going to need this at billions of tons
1:08:51
scale in the 20 forties, twenty 50s, twenty 60s.
1:08:54
And that's only going to happen if we can test it in the real
1:08:57
world at thousands and hundreds of thousands of tons scale today
1:09:01
and hopefully figure out what doesn't work right.
1:09:03
Like in some of these pathways just don't work.
1:09:04
Like algae sinking was a great example that was everyone was
1:09:07
very, very obsessed with it like four or five years ago.
1:09:10
There's a bunch of X prize stuff around it and what not.
1:09:12
And then people tried to do it and turns out algae really
1:09:15
doesn't grow in the open ocean and it's really expensive to
1:09:17
grow on the coast. And the durability is a little
1:09:20
uncertain and it has a bunch of impacts on nutrient competition,
1:09:22
these other things. And so now no one's really doing
1:09:25
that anymore because it was a pathway that for various reasons
1:09:28
didn't work out. And so success for us is both
1:09:31
figuring out what which of these pathways are the most promising,
1:09:33
but also hopefully figure out which ones are dead ends and not
1:09:37
sinking too much more resources in them.
1:09:39
What so, well, will we ever see a world where carbon dioxide
1:09:42
removal is priced to, I don't know, $10 a ton or something
1:09:46
where you you can stick it on your aviation fuel and it
1:09:49
doesn't price people out of being able to fly on holiday?
1:09:52
I mean, it's, it's never going to be $10 a ton, right?
1:09:54
I mean, if you, if you buy an offset on, you know, the
1:09:57
exchanges today, you can get an offset for $4.00 a ton.
1:09:59
But that's not worth anything in the real world because it's not
1:10:02
real. It's paying someone to cut down
1:10:04
a forest they were never going to cut down in the 1st place.
1:10:06
You know, real durable carbon removal is always going to be
1:10:08
pretty expensive. Now our goal as a field is to
1:10:10
get it down to $100 a ton. You know, then it's maybe
1:10:13
increasing the the cost of your flight by 25%, which is still
1:10:17
not great. Maybe some of these pathways
1:10:19
like sufficient mineralization at at billion ton scales could
1:10:21
get down to $50 a ton. But it, it ultimately is just a
1:10:25
really big challenging thermodynamic process to get
1:10:29
diffuse carbon out of the atmosphere into a durable form
1:10:32
at large scales. And again, even even at $50 a
1:10:35
ton or $100 a ton, you know, places that have had real carbon
1:10:39
prices, EUETS is a good example. It's the price there now is $70
1:10:43
a ton. Like that's not that different
1:10:45
from what we could get the cost of durable to Cdr down to.
1:10:48
And then these carbon prices are going to increase as we pick the
1:10:51
Lohini fruits and as it gets harder to decar, decarbonize
1:10:54
some of these things. Yeah, I've always worried about
1:10:57
the thermodynamics because you're essentially reversing all
1:11:00
of that energy that's been released and built modern
1:11:02
civilization. That's why it's cheaper not to
1:11:04
put the CO2 up there in the first place.
1:11:06
Right, right, right, right. Well, this has been an amazing
1:11:09
conversation, Zeke, and I just want to say thank you so much
1:11:12
for for sharing your time and, and, and expertise with us.
1:11:15
I, I feel, I don't know, do I feel more a little bit more
1:11:19
cautiously optimistic than when we started?
1:11:21
I think I possibly do. But I'm also daunted by the
1:11:24
scale. I mean, even, you know, there's
1:11:27
some of these technologies, they sound terribly promising.
1:11:29
You think, wow, this is going to solve the problem.
1:11:31
And then you, you know, you, you in the cold light of day, OK,
1:11:34
right. That's going to be, you know,
1:11:36
10th of a thousandth of 1%. It's probably still worth doing.
1:11:41
Well, you know, as, as my friend Bill Mckimmon once put it,
1:11:43
there's, there's no silver bullet, but there's silver
1:11:45
buckshot when it comes to climate change, right?
1:11:47
And, and we, we also just don't know at this point what is going
1:11:50
to be the most promising thing, right?
1:11:52
It reminds me a lot of YASA, the famous International Energy
1:11:55
modeling group back in the 1980s had this set of very prominent
1:11:59
projections saying that the world is going to be 80% nuclear
1:12:01
powered by the year 2000. It's going to be the technology
1:12:03
that, you know, takes over the world and, you know, maybe we'll
1:12:06
be 80% nuclear fusion powered by the year 2080, who knows?
1:12:10
But I think, you know, the the past is littered with the bones
1:12:13
of failed energy projections. And so we should be pretty
1:12:16
ecumenical where we place our bets today.
1:12:18
That's a good place to end. Let's be ecumenical.
1:12:21
Thank you, Zeke, and love to have you.
1:12:23
Have you back on the show in in a few months time to give us the
1:12:26
update about where things are because this is a rapidly moving
1:12:29
space and that's one of the things that makes it so
1:12:31
interesting. So anyway, thanks again for
1:12:32
joining. US Thanks, Mark.
1:12:37
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1:12:40
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