I am a geoscientist who thinks about energy systems and climate policy, and while I have some general knowledge of energy systems, I do not claim any policy expertise, so this is just me thinking out loud and in public …

WARNING: This blog post is more prescriptive than most things I write.


There are many people who put a lot of faith in the operation of markets who like to see governments do as little as possible.

Often, these people are OK with government action if someone can demonstrate that there is a market failure that government can address.

For the climate challenge, the most well-known market failure is the failure of markets to reflect future costs of climate damage in current prices. Where there is no price signal from future climate damage, markets continue to operate as if the operation of markets will not cause any climate damage — and this is driving us to dangerous climate change.

Economists often conclude that the most efficient way to represent this “unpriced externality” — an external cost that is not represented in market prices — is to have a carbon tax (or fee, if you prefer). A problem with this approach is that taxes are politically unpopular. A basket of policy approaches have been tried instead: carbon-trading markets, subsidies, regulations, etc.

These policies that drive technology deployment are addressing the “cost pricing failure” — the failure to represent costs of future climate damage.

“Unpriced future climate damage” is a market failure that is impeding deployment of clean energy technologies, but there is another market failure that is impeding development and improvement of energy technologies.

Horseshoe crab

Think of all the benefits of technology that we have today. Right now, you are using a computer and staring at a monitor screen. You have a cell phone. You’ve ridden in cars and flown in airplanes.

When these technologies were developed, some proprietary knowledge was generated and patented and this is a mechanism by which investors got rewarded for investing in innovation.

However, such innovative efforts also produced a lot of knowledge of a sort that is not patentable and where the benefits were not privatizable.

People watch each other.

When people see someone try to do something and fail, that gives people ideas on what they could do differently to succeed.

When people see someone try to do something and succeed, that gives people ideas on what they could do even better to out-compete them in the market.

Look around yourself right now: Can you find a single product in your field of view that was not informed by non-privatizable knowledge generated by private investment?

One of the things in my field of view is my DSLR camera.

This is a Canon camera, but the camera looks very similar to a Nikon or a number of other brands. Camera makers have converged on similar designs because there is non-privatizable knowledge about what works, what can be manufactured cost effectively and what can be sold into a market at what price.

Billboard in Wyoming, 2010

Economies and societies benefit from the non-privatizable benefits of private investment.

In most areas, we just accept that investment will be motivated only by privatizable benefits of an investment, and the entirety of non-privatizable benefits will go to other individuals or society-at-large. But the urgency and scale of the climate challenges warrant addressing this market failure specifically in climate tech innovation.

We can accelerate development and deployment of energy technologies that can help us attain net-zero emissions as soon as is practicable.

It is of course important to publicly fund the basic research that is the seed corn for long-term economic growth. But it takes risk-accepting investors to provide resources to develop the best ideas of scientists and engineers to the point where there is a product that can compete in the marketplace.

If the main reason we want private investors to invest in clean energy technologies is to benefit society, wouldn’t it make sense for society to provide incentives to generate that societal benefit?

The failure to adequately incentivize people to rapidly generate shared knowledge about better energy systems is a “benefit pricing failure” — a failure to provide a price signal to investors that reflects non-privatizable benefits of energy innovation.

Nearly everyone will benefit from cheaper clean energy technologies, especially-when those technologies can be nearly as cheap or cheaper than their CO2-emitting alternatives .

Ochopee, FL

In addressing climate challenges, one important market failure is the failure of markets to price social costs of future climate damage. Another important market failure is the failure of markets to price the social benefits of future cheaper clean energy technologies.

Policies that address the failure to price widely-shared benefits of energy innovation can be complement policies that address the failure to price widely-shared costs of climate damage. These policies address different market failures but are aimed at achieving the same goal.

And these two sorts of policies are complementary. Whatever the policy is that is aimed at driving deployment, having cheaper technologies will make that deployment-driving policy even more effective. With cheaper technologies, more clean energy technologies can get deployed faster and at lower cost — enabling earlier and deeper reductions in emissions.

We are not in an “either/or world”. The climate challenge is daunting enough that we need to live in an “and/and world”. We need policy drivers that promote deployment of clean energy technologies and we need policy drivers that promote development of better and cheaper technologies that are ready to be deployed.


We do not have to choose between policies that drive deployment of existing technologies and policies that drive development of better technologies.

We can do both and we should do both.

Hydrogen production from curtailed generation


There has been a lot of talk about making electrolytic “Green Hydrogen” using electricity from wind and solar power that would otherwise be curtailed. Less climatically helpful, there is also potential to use electricity from natural gas generators that would otherwise be idled.

Tyler Ruggles set out to answer the questions:

1. How much additional flexible load could we put on electricity systems before we would need to add more generating capacity?
2. In an economically efficient system, how would the fixed generation costs be allocated across fixed and flexible loads?

This study was published in Advances in Applied Energy under the title, “Opportunities for flexible electricity loads such as hydrogen production from curtailed generation”.

Tyler H. Ruggles, Jacqueline A. Dowling, Nathan S. Lewis, Ken Caldeira, Opportunities for flexible electricity loads such as hydrogen production from curtailed generation, Advances in Applied Energy 3, 100051, 2021.

The system considered by Tyler is represented by the following figure:

The system considers several generators, a fixed (i.e. specified and unchangeable) electricity load, and a flexible electricity load, here represented as electrolytic production of hydrogen gas. The dispatchable generator can be thought of as something akin to natural gas, but is left unspecified.

The basic results are summarized in this figure:

The last column (Renew+Storage) is perhaps the most relevant to ongoing discussions of “Green Hydrogen”. In this case, all electricity is produced with wind and solar power. Because of the high cost of storage, with low amounts of flexible load, it is economically efficient to build extra wind and solar generation and then discard some of this potential generation much of the time (curtailment).

However, if we have a lot of excess wind and solar capacity, that means there should be times when there is some excess generation capacity that is going unused. Tyler showed that, with a system sized to meet peak demands, there is some underutilized capacity nearly all the time. Because this underutilized wind and solar capacity has effectively zero variable cost, this excess electricity generation can be offered for free.

Because systems are sized to meet peak demand and there is almost always some underutilized generating capacity, a small amount of flexible load can be added to the system at effectively zero electricity cost and operate at high capacity factors.

The problem is, as additional flexible load is added, there is less and less unclaimed free electricity to go around, and so additional flexible loads need to operate at lower capacity factor, or additional generating capacity would need to be added to the system.

Both of these things cost money.

As can be seen from the above figure, flexible loads can be added to the system with effectively zero additional generating capacity to the point where the flexible load is about 20% of total load.

In other words, if a system is built to satisfy firm loads, it is likely that an additional 25% of that fixed load can be used to satisfy flexible loads with out any additional capacity expansion.

Between about 0.2 and 0.8 (20% and 80% of total load) in the above figures, there is a transition zone, where adding more flexible load would motivate building additional generating capacity, and so the flexible load would need to contribute to this capacity expansion.

When the flexible load is already representing over 80% of the total load, additional flexible load basically requires 1-for-1 expansion of generating capacity and so the flexible load bears the full cost of capacity expansion.

The figure above illustrates this transition. Below a flexible fraction of total load equal to 0.30 in this example, the flexible load draws primarily on capacity that was built to help meet peak electricity demands. Thus the flexible load can largely be a free rider.

But at a flexible fraction of total load equal to 0.40, additional capacity must be added to meet this flexible load. In this case, the flexible load would need to pay for that capacity expansion.

Tyler created this graphical abstract in an attempt to summarize the findings of this study.

As an aside, Tyler has training as a high energy physicist and was working at CERN when I hired him as a postdoctoral research scientist in our group. His most highly cited paper is about Higgs bosons.

My experience is that the most valuable qualities in a scientist include things like creativity, intelligence, work ethic, ability to complete projects, ability to work well with others, writing skills, math skills, etc. These are qualities that Tyler has in abundance.

Our goal is to do simple analyses to highlight fundamental principles. Smart people can learn domain knowledge quickly. This is the kind of analysis for which physicists are well suited.

This study has come to conclusions that are likely to stand the test of time:

  1. In systems designed to meet variable fixed loads, there is almost always some excess generating capacity and so almost always some electricity available to power flexible loads at the variable cost of the generator.
  2. As this excess capacity is increasing utilized, typically when flexible loads exceed 20% of total demand, additional flexible loads will require some additional generating capacity, and in an economically efficient system this cost will be shared between fixed and flexible loads.
  3. When flexible loads exceed about 80% of total demand, nearly every increase in flexible load requires a corresponding increase in generating capacity and so the flexible load would bear the full cost of this capacity expansion.

Replenishing the wind


People sometimes presume that when scientists set out to test a hypothesis, they are engaged in motivated reasoning and want to show that the hypothesis is correct.

While there might be some merit in that presumption, it is also the case that there are few things more pleasurable to the working scientist than being presented with evidence that your beliefs are false.

Working with Enrico Antonini, I recently had just such a pleasurable experience.

Like many other energy system researchers, I thought kinetic energy removed by wind turbines in large wind farms was replenished primarily by downward transport of kinetic energy from the overlying free troposphere.

For the first row of wind turbines, most of the kinetic energy transport is horizontal with the winds. However, each wind turbine can remove more than half the kinetic energy that passes through the disk swept by its rotors. The wind does not have to pass through many wind turbines before horizontal transport of kinetic energy is largely depleted. A source of kinetic energy is therefore needed to explain why wind turbines can still generate energy even when they are not in the first several rows of wind turbines.

Many energy researchers, including me, thought the wind energy was maintained by downward transport of kinetic energy from the overlying free troposphere. For example, in a 2017 paper published in PNAS, with Anna Possner as lead author, we wrote:

However, it remains unclear whether these open ocean wind speeds are higher because of lack of surface drag or whether a greater downward transport of kinetic energy may be sustained in open ocean environments.”

I believe many people held this view. For example, a paper was published in Geoscientific Model Development with a nice illustration of this mental model, showing a downward flux of kinetic energy


Enrico Antonini did some nice work in a paper published in PNAS this week that expands on a paper published in Applied Energy earlier this year. The Applied Energy paper showed how maximum power densities in regional scale wind farms are limited to a few watts per square meter, and are related to the Coriolis parameter times the pressure gradient.

In these papers, Enrico provides compelling evidence that the kinetic energy removed by wind turbines is replenished primarily by acceleration of air masses within the boundary layer by large-scale pressure forces (which are no longer balanced by apparent Coriolis forces due to the slowing of winds caused by the wind turbines).

Below is a schematic diagram of how things seem to work. Normally, large-scale pressure forces are balanced by apparent Coriolis forces resulting in what is known as “geostrophic flow”. However, as wind turbines remove kinetic energy from the winds, the apparent Coriolis forces weaken, and the unbalanced pressure gradient forces accelerate the air within the boundary layer.

Very little of the replenishment of wind energy is associated with downward transport of kinetic energy from the overlying free troposphere. The dichotomy we presented in our 2017 paper was a false dichotomy. Open ocean wind speeds are higher, but not primarily because there is less drag and not because there is substantially more downward transport of kinetic energy. The explanation for higher wind speeds over the ocean has to do with higher horizontal pressure gradients.

In the supporting material to the 2017 paper, Anna and I showed how wind power potential was closely related to heat fluxes at the planetary surface (blue are ocean areas, green is land; top to bottom is northern latitudes, tropics, and southern latitudes).

We presented this result without firm theoretical foundation. But now it seems that wind speeds over the ocean are high largely because ocean heat fluxes are high, and they can produce large temperature gradients, and these large temperature gradients can produce large pressure gradients, and large pressure gradients can drive strong winds.

Additionally, the theoretical understanding that Enrico developed predicts a length scale for recovery of winds downstream from a regional-scale wind farm. This length scale is the product of a time scale related to the Coriolis parameter times the geostrophic wind speed. The theoretical prediction of a length scale of several tens of kilometers is nicely supported by a recent study of wind speeds near large wind farms in the North Sea that which found a similar length scale in detailed simulations.

It is a real pleasure to be able to work with nice, smart, and productive people like Enrico Antonini. It is a privilege to be able to hire a bright early-career scientist who can show me my beliefs were wrong. And it is really nice to be working in a community where there is no great stigma to being wrong, if you are willing to adjust your beliefs in the light of new evidence.

On a final note, Enrico is on the job market. For his Master’s work, he worked at the scale of the turbine blade. For his PhD work, he worked at the scale of optimizing wind turbine positions within a wind farm. For the first part of his postdoc work, he worked at the transition between wind farm scale and what we might call the mesoscale. Now, he is engaged with a study on placement of wind farms in the context of continental-scale optimization.

Very few postdocs develop a fundamental theoretical understanding that makes testable predictions and has real world implications for energy system transition. (Enrico’s understanding can help people make a quick estimate of how closely wind farms can be spaced without them interfering with each other too much.)

If your department is would benefit from hiring somebody who understands scale-transition issues related with wind power development, you need look no further than Enrico.

High Energy Planet: Interview transcript

This is an edited transcript of an interview I did with Katie Auth and Rose Mituso for their High Energy Planet podcast. They were kind enough to allow me to reprint the transcript of our discussion here. Originally distributed on 7 June 2021.

I did some copy editing to improve infelicities of verbal expression, but tried not to change meaning. [Bracketed clauses were appended to two sentences a little too unqualified for my liking.] You can go to the High Energy Planet podcast for a more literal transcript.

I thank everyone at Energy for Growth Hub who helped make this a productive and enjoyable experience.


KATIE:  Ken, welcome to High Energy Planet.  It’s so wonderful to have you here.

KEN:  Thanks for inviting me.

KATIE:  So we’re just going to dive in with a pretty big question, which is a couple of years ago you tweeted, “Imagine it’s the year 2100 and the poorest parts of the world are prosperous and carbon-free.  What had to be true to make that happen?”  And I’m curious how you yourself would answer that question.

KEN:  I’m not an energy-systems engineer, and so I’m a little reluctant to make very specific predictions about future trajectories of energy systems.  But to my mind, while wind and solar and a lot of these other technologies have a lot of nice properties, they require a real transformation of how our whole electricity grid works.  It’s much simpler to have centralized power generation and distributed consumption. 

There are very few energy sources that can provide huge amounts of power in concentrated forms with proven technologies without emitting carbon dioxide into the atmosphere.  Nuclear power is one of the very few technologies that could potentially meet those requirements.  And so if you would ask me, like, what’s the most likely way we can have a prosperous future with low carbon emissions I would guess it’s going to depend a lot on nuclear power.  That’s not to say over the course of the rest of the century a lot of other technologies could be invented and developed.  So I’m not making a prediction.  But if you’re asking for my sense of what’s the most likely path to be successful given what we know today I would guess a heavy reliance on nuclear power.

KATIE:  Not an uncontroversial position to take at the moment.

KEN:  One of the things – and this is actually in many different contexts – I’ve found that often it’s better to argue for good process than to argue for specific outcomes.  And so I don’t pretend I know what’s going to be the best technology mix in 2100. 

But I do know that if we prematurely push things off the table and don’t subject various technologies to a fairly objective analysis that we might end up building some things that aren’t so good and overlooking things that could be very helpful.  My focus is on trying to get good process and open, transparent, inclusive processes with obviously democratic and local determination for people [i.e., respect national sovereignty].

ROSE:  So Ken, continuing this theme of prosperity and climate and balancing those two things, you authored a paper last year that found that if poor countries waited to decarbonize until they reached about $10,000 per capita GDP, it would cause less than .3 degrees Celsius’ additional warming.  And that suggests that we should just leave poor countries to develop and kind of take down the climate pressure on that side.  But on the other hand you’ve also returned a paper finding that less-wealthy countries shouldn’t be allowed to get locked into long-term fossil-fuel infrastructure.  So how do we reconcile those two things?

KEN:  Well, first of all to push back a little bit on your language, I probably wouldn’t have said “shouldn’t be allowed,” because I don’t think it’s my responsibility to tell others what they can and can’t do.  And so…

ROSE:  Very fair point.  [CROSSTALK] You pass the Energy for Growth Hub Climate Justice Test.

KEN:  [LAUGHTER] And so, the question is: How can we help make it in everyone’s self-interest to behave in ways that are also good globally? 

If you look historically, the amount of emissions that have come out of sub-Saharan Africa is climatically negligible.  It’s a little odd for the West, who’ve developed based on fossil-fuel emissions, to say to other countries, “Well, you can’t develop the same way we did.” 

If you’re developing on a fossil-fueled economy what could we do to make it an easier transition off of that?  And this is, again, coming back to this nuclear issue. 

Let’s say you build a natural gas plant and it’s centralized.  Maybe later you’ll replace that with a nuclear power plant and you still have a hub and spoke kind of electricity system.  But if you think the future’s going to be wind and solar then you might want to build a different kind of electricity grid now even if it’s fossil fuel, in anticipation of this distributed system later.

ROSE:  I think then this for me naturally leads to this question of, well, the people who are actually locked in are the rich people.  How do we square that circle?  You know, you’ve advocated for hard zero-emissions targets and you’ve likened this kind of hilariously to we need to seek to fully eliminate muggings of older ladies, rather than setting a rate for muggings that we can live with, you know?  So basically we can’t live with old ladies being mugged, and we shouldn’t live with old ladies being mugged, and we shouldn’t live with more carbon in the air.  But then you’ve also expressed a lot of skepticism about the viability of (coupled removal) at scale, which is central to many of our climate models and to this world that we live in that is fossil-based now and into the foreseeable future.  So how do you reconcile these two positions if, okay, putting poor countries to one side you have some breathing room?  What do we say to the rest of the world?

KEN:  I’ve been a climate scientist, biogeochemist and climate physicist and so on, for my whole career.  And then over the last years – more recently switched to trying to focus more on energy systems and solutions.  With that was the recognition that most people most of the time operate in what they perceive to be their self-interest, and that you’re going to solve this problem when you align people’s self-interest with a more global interest.  One of the ways you do that is by making the better energy sources even better and cheaper so that it’s the least cost approach. 

In the same way that there is a portfolio of energy technologies that will be used, there’s a portfolio of political strategies.  I find this somewhat disturbing, that…  Some people should be working to pass legislation through Congress.  And that means you need to – for the way the Senate is now that you need to get Republican votes.  And so you have to be very careful.  And there’s other people who should be saying, “oh, we need zero emissions today, and we should be sending boatloads of money to poor countries to pay their cost differential.”  I see these different political strategies as supporting each other.

I wish that people could appreciate that there’s value in political disagreement.

ROSE:  It’s an ecosystem.

KEN:  Yeah, and that – and it really bothers me to go on Twitter and see people badmouthing each other who are working towards the same goal through different strategies.  Because these strategies are complementary, if people would focus a little more on advancing their positive vision and a little less time expressing their negative energy about somebody else’s vision, we’d all be better off.

KATIE:  So the political strategy of climate alarmism really didn’t work particularly well for about three decades.  But now terms like “climate emergency” and “climate crisis” are part of policy lingua franca, and climate action is at the forefront of many policy agendas, at least rhetorically.  So what do you think was the tipping point?  And does using a framework of urgency change the way we think about or react to climate change?

KEN:  One of the things that was important for changing the political landscape is the reduction in costs in wind and solar power, that in large part was brought about by Germany’s Energiewende program.  The idea that it might actually be feasible to deploy some of this stuff, it might not cost that much, moved a lot of people to see the energy system transition as something that might be done realistically. 

This shows the importance of cost, in that wind and solar got cheaper, making it feasible to deploy. This made people take energy system transition more seriously.  That’s one component.  A more thorough-going energy system transition will depend on making other technologies cheaper as well. 

With regard to rhetoric, that’s a tougher question.  The social dynamic encourages a ratcheting up of rhetoric, so that, okay, we have two degrees.  Well, I’m going to say we should stabilize at 1.5 degrees.  Well, I’m going to say 1.25.  I’m going to – you know?  You can always get some social credit by saying something slightly more extreme than what the mainstream view is now. 

I used to say things like, “oh, we shouldn’t research adaptation because that will make people acknowledge that there’s going to be climate change, and that – just make it more likely, so we should just work on climate-change avoidance and not on adaptation.”  And I used to be somebody who was taking the more extreme positions and saying negative things about people who are taking more compromising positions. 

I don’t think any of my beliefs about, like, if I were the benevolent dictator of the world what would be the good thing to do is, have shifted.  What has shifted is my sense of how change happens in the world. 

Change happens by making more people see it in their self-interest.

ROSE:  You sound like a man who’s briefed Congress, Ken [LAUGHTER].  You know, out of the lab and into Congress.

KEN:  Well, one of the most depressing things for Congress was – this was on ocean acidification – I testified in a hearing for some legislation for money to fund research into ocean acidification.  At the end of it, after the formal testimony was over, the staffer walked up to me and said, “Okay, so what part of ocean science’s budget shall we take this money from?”

ROSE:  Oh no.

KEN:  “Because of course we’re not going to expand funding for marine sciences.”  And I felt, like, oh man, I did all this work just to shift…

ROSE:  Oh Ken.

KEN:  …(how) that marine science (inaudible) was.

ROSE:  There’s some species of jellyfish or octopus or something that’s dead because of you [LAUGHTER], unstudied.


ROSE:  Coming up, we ask Ken about his mixed feelings about geoengineering and his new approach to Twitter.

KATIE:  And we play Rant or Rave to find out about his checkered past as a bassist and a pumper of crocodile stomachs.


KATIE:  So Ken, you’ve been advising Bill Gates for about 15 years I think on climate change, arranging learning sessions for him with climate scientists and thinkers from around the world.  I’m actually curious, how did you go about designing that curriculum when you’re dealing with one of the most complex and multidimensional issues on the planet?  Where do you start?

KEN:  What I really liked about these sessions is that I could get these world’s leading experts in whatever – hydrogen, cement, battery technologies, whatever – and I could be there asking the stupid questions and being the student.  And being willing to expose my own ignorance all the time – I think me feeling comfortable with that also let me play this role well. 

I figure if I have a question there’s probably other people in the room with the same question. 

I used to feel like I knew what to do politically and that I also felt like I knew a lot of things.  And as time has gone on I’ve become less sure I know the right things to do politically and more accepting of a diversity of political strategies.

My awareness of what I don’t know has grown faster than my knowledge. 

This has put me in a good position to be in these kind of helpful and advisory roles.  Because – and I also have a commitment to process – let’s have an open, inclusive, and fact-based process.  And so all of these qualities put me in a good position to be in roles where I’m trying to help develop a good process, and bring in good information, and help facilitate others to make good decisions.

ROSE:  That’s really great, Ken.  I wonder how much this kind of softening of your posture has equipped you for Twitter fights.  But that’s – we’ll discuss that later.  Where, you know, it’s very absolutist now, like, where you have to know and speak with so much confidence.

KEN:  I’ve actually changed my Twitter strategy substantially and with very positive outcomes. 

Basically I’ve decided to try to not say anything negative on Twitter, and not to respond to negative comments to me, and try to be entirely positive on Twitter. 

And I see this in my own family relations or spousal relations as well.  Often we say negative things and it’s more about us releasing our negative emotions, and it’s not really about trying to effect positive change in the world. 

It’s very rare that a negative statement produces a positive outcome. 

I see this even with my postdocs and students, where if I’m not very careful, even if I’m trying to make a positive suggestion, people can hear that as a criticism of what they did wasn’t good enough.

People get hurt very easily.  We’re just not aware of how much our negative statements hurt people. 

Unless you’re really sure that a negative statement will produce a positive outcome, you shouldn’t do it. It’s more about yourself trying to get attention or releasing emotions, and not really about trying to help anybody.  And so, yeah, I think just being a little thoughtful – am I helping somebody by doing this?

KATIE:  So we wanted to talk a little bit about geoengineering.  In the past you’ve called yourself a [quote] “reluctant advocate” of researching solar geoengineering.  And as of 2014 you thought there was maybe something like a 20% chance that somebody would ultimately try it.  And, you know, now we’re in 2021–would you bet on different odds today?

KEN:  All the model simulations of solar geoengineering suggest that it would basically work to offset most climate change for most people, most of the time. 

Now, it doesn’t save you the need to do an energy-system transition, because everybody acknowledges that if greenhouse gases continue to accumulate in the atmosphere and you continue engineering the planet to mask that, that eventually that’s going to lead to some pretty nasty outcomes. 

On the other hand, if we get to mid-century or beyond and there’s massive crop failures throughout the tropics and widespread suffering, and richer countries aren’t really doing anything to alleviate that suffering, solar geoengineering is basically the only way known to cause the planet to cool within years to decades.

Basically if you zero out emissions the planet even continues to warm; it doesn’t start cooling for centuries.  And I don’t know what the likelihood of some kind of crop failure throughout the tropics is.  But, if that should happen… 

Well, first of all I’d also like to say that I don’t think there’s any reason why anybody, even in that situation, anybody would need to go hungry in the world.  Because there’s enough food produced, if you look at all the waste of food going on in the United States and Europe and so on.  I think if there ever is geoengineering it’s going to be multiple failures.  First of all, the failure of the social system to prevent the CO2 emissions.  But, then the direct climate crisis.  But then it’ll also need to be a social failure that the global community doesn’t mobilize to address issues.  But, the global community hasn’t been very good at mobilizing to address important issues to date. 

I don’t know what the likelihood that there’ll be something perceived as an acute climate crisis that needs to be dealt with right now.  But if that’s felt the only – solar geoengineering is really the only thing that could cool the planet [within the politician’s political career].  And, if you were the leader of a country and people were starving to death, and you felt that you could save lives by solar geoengineering, you would be remiss not to give it serious consideration.  And so I don’t know what the chances are of having widespread famines or something like that, but if that happens the possibility of solar geoengineering could be quite high.

KATIE:  Do you worry that the prospect of geoengineering, kind of having this as a last-resort solution, kind of impedes action now?

KEN:  I don’t think it really does.  There are different metaphors, but I would look at solar geoengineering as like morphine for the cancer patient, in that it provides some symptomatic relief but it’s not addressing the root causes.  If you have cancer, morphine can be extremely valuable.  So symptomatic relief shouldn’t be scoffed at. 

But I don’t think that the prospect of solar geoengineering is preventing action on climate change.  There was some rhetoric in that direction maybe a decade or so ago.  But I think now everyone understands that even if you’re doing solar geoengineering you still need to stop emitting CO2.  It’s doesn’t work to do both at the same time.

KATIE:  Yeah.


ROSE:  Okay Ken, now it’s time to play Rant or Rave.  So this is a quick-fire game where we say a word or a term and you go on a short – very short rant or rave about it.  Are you ready?

KEN:  Okay, I’ll give it a go [LAUGHTER].

ROSE:  All right, rant or rave: hallucinogenic drugs?

KEN:  I enjoyed them when I was in high school.  I would be afraid to take them now.

KATIE:  Rant or rave: pumping crocodile stomachs?

KEN:  Not pleasant, a little bit similar to (inaudible), but a very interesting experience.  Before I went to graduate school I was a software developer in the financial district in New York.  And between software development projects I did other kinds of projects.  And one of the things I did was go to Mexico and work as a field assistant to some herpetologists in the Mexican rainforest, the Selva Lacandona.  And one of the things that they were doing was ecological study of the crocodiles there and looking at both their population and what they were eating.  And so we were out there trying to catch crocodiles, and tag them, and pump their stomachs and see what they’re eating.  And so a crocodile sits with its mouth open and basically waits for a fish or something to swim past it, and then it closes its mouth.  And even a grownup crocodile will eat little bugs and little tiny fish.  And they might just get, like, one fish a month.  And that was actually the experience that made me go back to graduate school and get a PhD.  Because I thought, oh, if I don’t get a PhD I’m always going to be somebody’s field assistant.  If I want to lead expeditions I have to get a PhD.  And it was a really fun and interesting thing, and really my motivation for going back to – to going to graduate school was to try to lead field expeditions in the rainforest, which I never did.  But I did finally get to go to coral reefs so that’s pretty good.

ROSE:  Climate purity tests?

KEN:  I don’t like them so much.

KATIE:  Okay, this is a throwback.  Punk-funk and Fists of Facts.

KEN:  I like playing bass guitar, and I still – I played last night, but just by myself.    I went to Rutgers College in New Jersey and a bunch of my friends and I all moved into New York City when we graduated.  And all my friends were artists and musicians in fairly reasonably-successful bands.  And I went and did computer programming work on Wall Street, which was, like, the boring thing to do. But I still played music with my friends, and we had a band and we called it “Fist of Facts,” an idea – even then it was the idea that facts did have this political import.  Even before graduate school I was still on that kind of thread [CROSSTALK]…

KATIE:  Science fights back.

KEN:  Yeah.  So – and we played – we were basically fans of Fela Kuti and had our downtown New York version of Afrobeat I guess and reggae kind of stuff.  So that was our [CROSSTALK].

ROSE:  That’s awesome. [LAUGHTER]

KATIE:  We have to look you up after this.

ROSE:  Definitely on (Spotify).

KEN:  [CROSSTALK] We’re not so good.  But we’re on Spotify, so… [LAUGHTER]

ROSE:  That is so great.

KATIE:  All right, final one.  Bets with Ted Nordaus?

KEN:  Oh yeah.  So we’ve had about whether…

ROSE:  The (peaking) emissions.

KEN:  …[CROSSTALK] have CO2 emissions already peaked?  And I think I’m going to be winning a bet very soon.

ROSE:  All right, good one.

KATIE:  Unfortunately yeah.

KEN:  And this was actually even symbolic on this bet, because we had to say what charity we wanted to give it to.  And I said I want to give to the Doctors without Borders to say, look, it’s not all climate change.

ROSE:  All right Ken, thanks so much for being with us on High Energy Planet.  We’ve really enjoyed this discussion; it’s been a lot of fun.

KATIE:  Thanks Ken.

KEN:  Thank you.

Podcasts aimed at professionals in other professions

I have been enjoying podcasts made by and for professionals in other professions. Sometimes, but not always, these podcasts related to my hobbies.

It becomes apparent that many of the same qualities are characteristic of people who are successful in different domains. Further, the advice people give regarding how to be successful is largely the same, independent of the specific domain. These qualities include (in no particular order):

— Working hard
— Aiming to be helpful and valuable to others
— Learning your craft skills
— Working even when there is no prospect for immediate reward
— Surrounding yourself with excellent people
— Being creative, trying new things
— Being a lifelong learner
— Being ready to drop a suggestion if nobody else is interested
— Being pleasant to work with
— Focusing on the success of the group effort, rather than individual glory

And some of my favorite podcasts are:

Bold as Brass Podcast
Host Melissa Brown chats with trombonists, tuba players, trumpet players and so on. It is really great to listen to people who have chosen to follow their life passion talk about their work and lives. (Nobody becomes a brass player to become rich.) Every episode is excellent but a nice one to start with might be the Roger Argente episode.

Recording Studio Rockstars
Likable hosts help make likeable podcasts. Lij Shaw asks good questions and always has a positive attitude. A good episode to start with is the interview with Rafa Sardina

These episodes contain both discussions about writing screenplays and about the screenwriting industry. For most people like me, the episodes that focus on craft are probably more interesting than the ones that focus on the industry. A good episode to start with might be the “Sexy Ghosts of Chula Vista“.

ICU Rounds
Episodes from before 2012, I believe, were meant to help intensive care unit doctors brush up for some sort of recertification exam. This gave wonderful insight into the goals of ICU doctors and what intensive care units are all about. A few episodes you might start out with include Patient-Ventilator Interactions and ventilator discontinuation, Smoke Inhalation Injury, and Therapeutic Hypothermia After Cardiac Arrest.

Ocean acidification: A career journey from curiosity-driven science to a search for solutions

I was asked by Stephen Macko to produce an abstract for a lecture for the University of Virginia this coming week, aimed at a general audience and centering on ocean acidification. The abstract went on a little long, so I thought I’d put a version of it here, with links. When I get a link to the Zoom, I’ll put it here. 3:30 PM ET on Thursday 4 March 2021.

Carbon dioxide is a greenhouse gas, but when it dissolves in seawater it becomes carbonic acid. In high enough concentrations, it can be corrosive to the shells and skeletons of some marine organisms. In lower concentrations, it can make it harder for many marine organisms to survive. This talk will discuss ocean acidification in the context of the arc of my career.

When I was in graduate school, I was motivated by concern about climate risks, but most of my research attention was focused on curiosity-driven questions — questions driven by a need to understand, and not by a need to solve any particular problem. As a consequence, my PhD research was largely about marine biogeochemical carbon feedbacks operating after many marine species were eliminated along with the great extinction event that wiped out the dinosaurs. One of the things that became apparent in doing that work, is that accumulation of biologically produced carbonate minerals in coastal waters must be very sensitive to ocean chemical conditions.

Title and abstract from my first paper (Caldeira, Nature, 1989). This two-page paper counted as my Master’s Thesis. I was told it was the shortest Master’s Thesis in NYU history.

A decade or so later, I was working on a project related to ocean carbon sequestration, and we were comparing the effects of atmospheric versus oceanic releases of carbon. We noticed that the changes in ocean chemistry inferred even for atmospheric releases were outside of the range of variability of ocean chemistry for most of geologic time. This observation led to a publication in Nature magazine, and activities helping to publicize the issue of ocean acidification, including congressional briefings and a major article in The New Yorker.

Illustration of study site and experimental setup described in Albright et al, (2018)

Coarse-resolution ocean modeling can yield only so much information, so I hired excellent postdocs with field experience and initiated a field program leading to the first experiments ever in which ocean carbonate chemistry was altered in situ in the absence of artificial confinement, and the biological response measured. These studies were also published in Nature magazine.

There is only so much diagnosing a problem can do. At some point, you want to solve the problem. I believe a large part of the solution will involve building a better energy system. I have been extremely lucky in that I have been given the opportunity to be leading a group of researchers, and supporting Breakthrough Energy (and Bill Gates) in some of their information needs aimed towards building a better energy system, one that can meet human needs without large negative environmental impacts.

Schematic diagram illustrating some possible options for net-zero emission energy systems (Davis et al, Science, 2018)

And now my soapbox: We need diversity not only with respect to gender, race, socio-economic background, career-stage and so on, but also in terms of curiosity-driven vs. problem-driven science, long-term monitoring vs. hypothesis-driven science, mechanism-based vs. system-level understanding, and so on. A robust scientific enterprise is a diverse scientific enterprise. 

Check out my google scholar page. If you want a copy of a paper, please feel free to write me at [email protected].

Wagner scores on YouTube

I am trying to maintain links to some good Wagner recordings with scores on YouTube. If these links are broken, please let me know by email. This is not meant to be complete, so email me about another version only if it is better or nearly as good.

Richard Wagner - Wikipedia


Performance: ???
YouTube site: TheOneAndOnlyZeno
Notes: Overture only
Length: 12 min


Performance: Joseph Keilberth cond/ Bayreuth Festival Orchestra & Chorus (1955)
YouTube channel: tomekkobialka
Notes: Complete performance
Length: 2 hours 20 min


Performance: Zubin Mehta cond/ New York Philharmonic Orchestra
YouTube site: Mirko Sattig
Notes: Paris version; Complete performance
Length: 3 hr 7 min

Performance: ???
YouTube channel: tomekkobialka
Notes: Overture and venusberg music only
Length: 25 min


Performance: Zubin Mehta cond/ New York Philharmonic Orchestra
YouTube channel: Mirko Sattig
Notes: Complete performance
Length: 3 hr 37 min


AKT 1 –
AKT 2 –
AKT 3 –
Performance: ???
YouTube site: TheOneAndOnlyZeno
Notes: Complete performance
Length: 1 hour 15 min; 1 hour 13 min; 1 hour 23 min


Performance: Solti
YouTube channel: tomekkobialka
Notes: Complete performance
Length: 2 hr 26 min


Performance: Solti
YouTube channel: tomekkobialka
Notes: Complete performance
Length: 3 hr 49 min


Performance: Solti
YouTube channel: tomekkobialka
Notes: Complete performance
Length: 3 hr 57 min

Performance: ???
YouTube site: Mirko Sattig
Notes: Complete performance
Length: 18 min


Performance: Solti
YouTube channel: tomekkobialka
Notes: Complete performance
Length: 4 hr 25 min


Performance: Karajan 1981
YouTube site: Mirko Sattig
Notes: Complete performance
Length: 4 hr 15 min

Climate and energy discussion on ‘Straight Talk with Hank Paulson’

The following is a lightly edited transcript of my (regular font) conversation with Secretary Hank Paulson (italic font) on the “Straight Talk with Hank Paulson” podcast, released 19 Nov 2020.

Humans are very good at solving problems that are very immediate and where the person who solves the problem benefits from that solution.

Unfortunately, climate change is a problem that manifests itself over decades and centuries, and the benefits accrue to basically everybody but the costs accrue to whomever is reducing the emissions.

Welcome to Straight Talk, a podcast about big ideas from some of the world’s foremost thinkers and doers.

I’m Hank Paulson, Chairman of the Paulson Institute.

Today, I’m speaking with Ken Caldeira.

Ken is one of the world’s leading experts on climate change and currently serves as a climate scientist at the Carnegie Institution for Science.

He has made pioneering discoveries in areas such as ocean acidification and energy system modeling and is known to be an out of the box big picture science with diverse interests.

Ken, welcome to the podcast.

Hi, great to be here, Hank.

Ken, I’m really looking forward to our conversation today. I’ve talked with a lot of climate scientists but few of any or as good as you are in big picture thinking. You’re able to put it all together and break new ground in the questions you ask, the areas you study and the solutions you consider.

Valley Stream, New York (


But before going big, I’d like to go to near the beginning: How did you get interested in science and when did you first develop your strong interest in climate change?

I think my interest in science began when I was a kid, due to the Apollo space program.

The whole “landing humans on the moon” really excited an entire generation. And the reaction to Sputnik by the United States, in creating the Gemini and Mercury and Apollo programs, spurred a whole new thrust in improving education in the united states.

I’m hoping that energy and responding to climate change might have some of the same effect of really revitalizing science and education in the United States. It was these kinds of governmental programs when I was a kid.

But then how did I get into climate science?

As an undergraduate, I learned computer programming, and [after graduation] was doing software development in Wall Street in the Financial District, basically looking at mergers and acquisitions for places like First Boston and so on.

I remember reading an article in the New York Times. Steve Schneider spoke at a Congressional testimony and also spoke at a [AAAS] meeting and talked about how we might be melting some of Antarctica.

And this kind of blew my mind – the idea that us little puny humans could influence something as big as the Antarctic ice sheet or global climate really surprised me.

And so I just started going back to graduate school in the evenings just for fun to learn about it. And I turned out to be their best student. They offered me a fellowship. I quit my job on Wall Street and the rest is history.

Wow, I tell you, as I have gotten to know over the course of my career, people that are best in class in their various professions, they all have one thing in common, intellectual curiosity. Intellectual curiosity.

And, it’s amazing, I remember Sputnik like it was yesterday. It was just that was huge, wasn’t it? And then Neil Armstrong landing on the moon, Alan Shepard, all that.

It was a fascinating, fascinating, time in our history.

One thing that separates me from most other climate scientists is having spent (I forget what it was) six or eight years working in the financial district in New York because you get a real sense about … . You understand discount rates and you understand competing opportunity costs for using resources in one way rather than another.

I feel that this time in the financial district in New York has informed a lot of my thinking and was very useful.

Lower Manhattan (


We’ll get to that in a bit because one of the things that’s impressed me about my conversations with you is you really work to understand the economics of all these uh solutions or potential solutions and so when we get to talking about open air carbon capture and some other things you’re focused on the economic realities and a matter of fact everything you’re doing is grounded in in practical realities how will this work what do we need to do so let’s start with the basic core question how big a challenge is climate change?

There’s two different ways to think about how big the climate change problem is.

One is “Well, what are the bad things or possibly even good things that could happen with climate change?”

But the other is the game theoretic challenge of how hard is it to solve this problem because of its logical structure.

If we look out centuries [and ask] “what are the consequences of continuing in our current modes of generating energy or converting energy for human uses?” [we’ll find] that we’re adding greenhouse gases to the atmosphere and eventually we’ll melt all the ice sheets and sea levels will go up 200 feet. We’ll be restoring ourselves to the kinds of climate that existed when the dinosaurs were around.

I’m not with Leibniz and thinking this is the best of all possible worlds, but there’s a lot of disruption that comes with this change.

Losing essentially every coastal city in the world is a cost that we don’t want to take on. There are also concerns about crops growing in tropical countries – how it’s already difficult to work outside in the sun in most of the tropics and if it gets hotter and there’s already heat stresses causing reductions in crop yields … . And so, there’s potential for large parts of the tropics to become unsuitable for growing crops and so the risks are very large.

Unfortunately, humans are very good at solving problems that are very immediate and where the person who solves the problem benefits from that solution.

Unfortunately, climate change is a problem that manifests itself over decades and centuries, and the benefits accrue to basically everybody but the costs accrue to whomever is reducing the emissions.

This logical structure, where the costs are borne by people today but the benefits are widely distributed and come mostly far in the future, that’s a really tough problem from a political and economic perspective to address.

We’ve been doing some simulations using integrated assessment models. For the next 60 or so years we’re going to want to invest more in emissions reduction than that emissions reduction will offset in damages.

We’re asking this generation to invest for future generations, and that’s a tough ask.

Yeah. I totally agree that we do best when the crisis is immediate right as opposed to long term, and we also do best when the crisis is national as opposed to global, and this is longer term and global.

But, I want to turn that around a bit, because most of the thinking and it is directed where it should be when we’re looking at the most adverse consequences which are long-term consequences, but there are also some immediate consequences.

Wall Street (


Many people don’t understand that no matter what we do today, as a result of the carbon that’s already up there in the atmosphere, there are going to be some very real impacts of climate change some very real shocks in the next decades.

The question I have to you is: How should we look at those? And what surprises are out there that are possible in the next 10 20 30 years? And how should we think about resilience and adaptation preparing to deal with the shorter term shocks?

There’s evidence that global warming is causing storms to become more intense now. We’re also putting more and more infrastructure in harm’s way.

We can expect increased storminess increased flooding, increased heat waves leading to crop failures, and some deaths of vulnerable people.

But what we’re seeing in the next decades is going to be the tip of the iceberg.

Climate change is something that’s cumulative. Each emission basically adds another increment of warming.

If we stop emissions today the Earth doesn’t start cooling for the better part of a thousand years.

Even if we were to stop today, we don’t make things better we just prevent it getting worse.

And it’s extremely difficult to reduce emissions and so the likelihood is for emissions to go up, the amount of warming to go up, the amount of heat waves, floods, severe storms, and so on, going up.

I know that people focus on what’s coming in the next decades in an effort to try to motivate people to do something now but it’s really whatever comes in the next decades is like that’s just like the little tip of the iceberg and what’s really coming down the pike is really gigantic.

Yeah, I agree with you.

People have conflated two things: the “what’s coming in the next couple decades” and “what we need to do in terms of resilience and adaptation with the longer term issue in terms of mitigation”.

We don’t want to ignore what’s coming in terms of where we build and what we do because there are going to be some very real changes immediately and we need to prepare for those. But you’re totally right in terms of where the big risks are.

Most of the climate change that will happen in 10 years from now is already baked in. It’s really only one more decade’s warming.

If you’re trying to deal with the effects of climate change in 10 years it’s adaptation that’s going to reduce that risk.

We need to really get on the program of reducing emissions to prevent the much bigger changes down the road but [in] the near term it’s mostly about let’s build the right kind of infrastructure.

Absolutely. Let’s prepare. Let’s protect our economic security. Let’s adapt. Let’s build in resilience to deal with what’s going to come.

That’s a very, very, different problem from that of avoiding the very worst outcomes which are certain to come unless we act.

Natural gas plant near Gowanus canal, New York. (


I want to come back briefly to where you started because you read something about the Antarctic ice shelf melting and now a lot of respected scientists are saying that the process of irreversible melting is going on in Greenland and the Antarctic ice shelf. What does this mean in terms of sea rise and over what time period?

The central estimate for Antarctic melting is around an inch a year for the next 10,000 years or so. That’s more-or-less a foot a decade or more-or-less 10 feet each century, which is like a floor of a building.

And so what we’re doing over the next decades is really going to affect people living on this planet for many thousands of years.

Indian Point Nuclear Plan (


Ken, now this is a part of the interview I’m really looking forward to.

What are the things we can do what are the things that science can develop that will let us avoid these or help us avoid some of these most adverse impacts? Talk about science, where science is now, where we need to get. What are the areas where we can have big breakthroughs that make a significant difference?

The main cause of global warming is carbon dioxide emissions from the burning of fossil fuels in our energy system, and that’s both fossil fuels to generate electricity to provide gasoline for cars and jet fuel for airplanes and heat to make steel and aluminum, and so on.

Most analysts now believe that the way to move forward on this is to electrify as much of the economy as possible.

We see this transition now with going from gasoline cars towards electric cars, but electrifying the economy doesn’t do anything if you’re using coal to make that electricity in coal plants emitting the CO2.

The next step is to (the jargon is) decarbonize the electricity system. And that means either basing it on inherently carbon-free technologies like solar power wind nuclear. Or another idea is to burn the fossil fuels and then capture the CO2 and throw that CO2 underground. Now that unfortunately is still expensive.

The cost of solar and wind have come down dramatically.  The problem with solar and wind is that you often want electricity when the wind isn’t blowing and the sun isn’t shining and electricity storage is still very expensive.

Wind and solar can penetrate electricity systems a bit now but to really do the entire job with wind and solar we would need much better storage technologies than we have.

There’s a whole suite of different energy system innovations that people are thinking about.  There’re other sources of emissions like cement and land use change, but those are less important than the energy system.

That’s a very good summary.

Always when I will talk with people that are looking for huge scientific breakthroughs, I always come back and say to them, “It’s cumulative. Every bit counts whether it’s behavior change whether it’s reducing emissions whether it’s moving to cleaner renewable sources of energy.”

Marsh at Charles Point, New York (


But there also are some very big out of the box ideas that you’ve considered which is: “Is it irreversible the emissions we’ve put in the atmosphere?”

What about you’ve done work on open-air carbon capture talk a little bit about that in terms of what this is what the science is what the economics are how you think about it?

Let me talk about a few of these crazy out-of-the-box things which are fun and I enjoy, but before I do that let me just say, “I like thinking about the big breakthroughs and one of the crazy out of box things that could maybe come in the future …  “

We need to realize that if you think about how much solar power got cheaper over the last decade or two, and a lot of that was really Germany putting subsidy on rooftop solar and so on, and the Chinese responding to that by building all of these solar photovoltaic factories, and they just step-by-step increased the efficiency and reduced cost through hundreds of tiny little improvements.

And so, in the case of solar, at least, we saw more-or-less what you’d have to call in aggregate “a breakthrough” that really was the accumulation of a lot of tiny little improvements of learning by doing and so on.

While I’m going to talk about some big breakthrough kind of things we need to remember that a lot of progress comes in a lot of little tiny steps.

Ken, I agree with you totally and I’m a big believer that if we put a price on carbon emissions that we will see incremental steps that will add up and make a big difference.

If we have the right incentives the right regulatory policies the right way to price emissions and pollution will make a huge difference over time. And we never want to take our eye off that ball. And I think behavior changes, but I do think it’s interesting to talk about some of the big ideas.

The danger of course is people will say well maybe we don’t have to do anything because at the end of the day there’s some huge idea that’s going to save us all.

Imagine if it was 1920 instead of 2020.

The things we have today would seem like magic.

Solar photovoltaics – nobody ever thought about that. There was no silicon chip in 1920.

Nuclear power would have been just a science fiction story.

The idea that wind power would come back, that aviation would be big, that we’d have cars all over the place, and …

We do ourselves a disservice by not using a lot of imagination when we think about the future. We just shouldn’t believe our imagination too much. But anyway… so to come up with some of the basic ideas ….

One basic idea is, “Well, if we’ve emitted all this carbon dioxide to the atmosphere, can we go and grab it out of the atmosphere and pull it back out?”

And we know this is possible because plants do it all the time. Plants take carbon dioxide out of the atmosphere powered by sunlight and convert it into carbohydrates with chemical energy.

One way you can pull CO2 out of the atmosphere is to grow plants and that’s the whole idea of biofuels and bioenergy and so on. Or you could also potentially bury that biomass. And people have even talked about taking hydrogen from other sources and upgrading that carbon to make aviation fuels based on biomass.

The simplest way to draw CO2 out of the atmosphere is grow plants, but the problem is that plants take a lot of area and are very inefficient. But they are self-assembling little robots, so that’s good.

Various groups, especially one in Switzerland and one based in North America, have developed chemical processing approaches to extract CO2 from the atmosphere. The problem is it’s expensive.

That said, there are some very difficult to decarbonize parts of the energy system. Let’s say you want to fly from New York City to Sydney in an airplane. There’s just no battery that’s light enough to ever power a jet plane like that and so dense hydrocarbon fuels are still the fuel of choice.

The idea is, “Well, maybe you could still use fossil fuels for that long-distance aviation but then have a plant somewhere pulling that CO2 out of the atmosphere.” My guess is it might get used for these kind of niche applications but it’s not going to be the main show.

It’s just too expensive in my judgment.

There’s also sort of crazy out of the box ideas for electricity generation and my favorite one (and this one’s crazy a bit) is …

We did a study looking at the power in the jet streams. These are the those powerful winds that are more-or-less up above where the jets fly.

On a good sunny day you might get one kilowatt of power per square meter [from sunlight] in the middle of a desert in the middle of the day. You can get 10 or 20 times that power in winds in the jet stream.

If we could ever get flying wind turbines in the jet streams there’s more than enough power there to power all of civilization and it’s pretty steady. I don’t know if we’ll see that in the coming decades or even this century but I think sooner or later unless we find something really good like fusion, or something, my guess is someday we’ll tap into the jet streams.

There’s all kinds of ideas. Obviously, there’s a bunch of different nuclear power plant designs and I think nuclear power is something that I think is likely to play a major role in addressing the climate problem.

It’s one of the few technologies that fits into our existing energy system in a relatively easy way.

When solar was expensive, we looked for ways to make solar better and cheaper. I think if we had a concerted effort to make nuclear better and cheaper, it would likely play a major role in helping to address the climate problem.

Salt ponds near San Jose, California (


One idea that does work well in the climate models is this idea of solar geoengineering, of putting particles high in the sky above where jets fly, in the stratosphere, and reflect some sunlight from the Earth.

This in climate models works surprisingly well at offsetting most of the effects of high greenhouse gas concentrations.

It’s one of these things that almost works too well in the models because …

I’m afraid to do it in the real world, but if we actually believe the models and you weren’t worried about socioeconomic and political knock-on risks, just in terms of physical risk reduction, I would think putting aerosols in the stratosphere is probably sensible. But I’m not sure I believe our models enough to do that.

As you pointed out to me when we talked about it in the past it raises all sorts of ethical and political questions: Who would be authorized to do it? How would it be done?  And because when it’s done it affects everyone, it is it’s a very controversial subject, but it’s one that scientists need to explore and look at.

As I mentioned earlier, each carbon dioxide emission causes another increment of warming. And so if you stop greenhouse gas emissions, the Earth doesn’t start cooling. It just stops getting hotter.

But, if there’s ever a perception of a climate crisis and people demand that politicians do something to cool the Earth off, solar geoengineering is the only thing they can do that would cause the Earth to start to cool within their terms in office or within their political careers.

I don’t know if ever climate change will ever become perceived as an acute crisis that people need to address now, but if that public perception ever occurs the political pressure on a politician to do something will be immense.

Imagine if you were a leader of a country and you had repeated years of crop failures and famines were threatening your country.

And you thought that by doing a relatively cheap thing and putting some aerosols in the stratosphere, that you could protect the lives and well-being of the people in your country.

I think you would be remiss as a leader not to seriously consider solar geoengineering.

I don’t know what the probability of climate change being felt as an acute crisis is, but if you think that it’s substantially non-zero then you have to say, “Well, look, we’d better understand these solar geoengineering options because the political pressure to deploy them could become intense. And if it’s a really bad idea we better understand that now.”

Arizona-Utah border near Rainbow Bridge (


Let’s move right along here. What parts of the current climate science consensus might turn out to be wrong?

That’s a tough question.

I don’t know if it’s a climate consensus, but I think this question about: “To what extent is climate change going to be a slow gradual progressive thing versus it come in sort of jumps and starts and shocks?”

People talk about climate crisis and I’m just not sure. Climate damage tends to show up locally.

As there’s an extreme storm or there’s a flood or there’s a drought with a crop failure and so year by year, we have different localities that are experiencing crises. But, they’re basically local or regional crises – like Katrina hits New Orleans and maybe there’s disruption to the Gulf Coast, but basically the country’s economy goes on.

And so the question is: “Over the next decades, is it going to continue like that where basically you have a bunch of isolated regional effects and they’re addressed basically on a regional basis, or is it going to be something more like this coronavirus thing where something affects the entire world and the entire world says, ‘oh, we need to deal with this acutely now’?”

It seems like there’s one group that uses words like “climate catastrophe” words like “extinction” and views climate change as this acute kind of global disaster. And there’s another view of it – Well, there’s a lot of series of small local disasters that become more commonplace but at the system level is more of a cost than a catastrophe. It’s a local and regional catastrophe but globally it’s a cost.

I’m not really addressing your questions. I’m not saying it’s false. It’s more like an uncertainty that I don’t know. It’s the same with when I talk about geoengineering.

Will climate change ever be dealt with acutely as an immediate problem or will it always be everybody’s third or fourth or fifth biggest problem?

Black Rock Desert Wilderness, Nevada (


Most people, if you’re out of work or if you’re in sub-Saharan Africa, even if it’s a hot day, your problem is not having a job or not having money. There’s other big complicated things about this interplay between economic development and climate change.

If you gave somebody a choice of having three degrees higher temperature but having a full bank account versus being in poverty and in a better climate, a lot of people would take the bank account and the higher temperatures.

This question of: “How do we do both of these things simultaneously of have the world develop and increase people’s economic well-being at the same time that you’re protecting their environment?”

But our whole political systems … most leaders are focused on the short term on their time in office. Sometimes they’re looking a year or two ahead but very seldom are they looking really long-term, so short-termism works against us.

Luna Park, Coney Island (


But I would like to, as we’re talking about politics, I want to end by getting your thoughts on the politicalization of science.

We’ve seen it in climate change. We’re seeing it now with a pandemic. What do we need to do to take the toxicity out of the debate?

Now I’d always thought that when you look at competition, that academics and scientists are the toughest on each other in terms of peer reviews and so on so. I know you’re always going to have, and that’s healthy to some extent, but this has gone beyond that right.

So, what do we need to do? How do we deal with this and How big a problem is it?

Obviously this problem of not having shared facts is really terrible. I had always thought we will agree on the facts and our values will disagree. Then at least we could discuss assuming the same set of facts. That seems to have gone out the window.

I found that a few different things help. One is being willing to consider things like geoengineering and nuclear power — that you’re not coming in with a bunch of filters.

I think another thing that helps is a reiteration of shared goals that if you say, “Most people want a healthy growing economy. They want to see people in developing countries have access to more material goods and services. People would like to protect the environment.” And so [first] some reiteration of shared goals and then you can say, “Okay let’s have a discussion about how to attain these goals, and how to balance competing interests.” I think entering into the discussions and showing a willingness to be flexible [helps].

Too often in Washington, people personalize. If you disagree with someone in their position, too often people attack them and to attack their motives or go after them personally, rather than dealing with the facts.

But in any event, I think that’s a good note to end on because science is so critically important to our way of life and as you pointed out we’ve had so many breakthroughs over the last hundred years.

And we’re going to continue to have major breakthroughs if we move forward in the right way, so, Ken, thank you very much for joining us today and I greatly appreciate it.

Well, thank you for this opportunity

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Climate change as an incentive to future human migration

We (i.e., Min Chen and I) are physical scientists with no pretense to in-depth understanding of social and political dynamics. Yet we recently published a paper titled “Climate change as an incentive to future human migration“.

Discussing climate and population can be controversial. There is a long history of racist, classist, xenophobic writing on this topic.

And the sad history of physical scientists making blundering remarks about human beings provides plenty of motivation for amateurs to avoid commenting on anything related to projections of future human migration. Nevertheless, …

Physicists often make very simple quantitative models leaving out many factors to try to get some first-order understanding. For environmental scientists, this framing perhaps reached its apogee with John Harte‘s book, “Consider a Spherical Cow“.

Social scientists (with the exception of some economists!), aware as they usually are of the multiplicity of factors that influence the behavior of people in societies, are often loath to make quantitative models of social change. (In contrast, some economists take the quantitative results of “spherical cow” economics models such as DICE too literally, but that is another discussion.)

In developing the climate damage function for DICE-2016R, Nordhaus used regressions on gridded economic and climate data to estimate the effect of climate change on economic productivity. Noticing that population density was one of the factors in the G-ECON database considered in Nordhaus’s regressions, we thought, “What would happen if we applied Nordhaus’s methodology, but used it to predict changes in population density, rather than changes in GDP?”

We understand that a multiplicity of factors affect migration decisions. People have jobs and friends and families and speak specific languages and engage in idiosyncratic cultural practices. These factors can influence people to remain, even if their local climate deteriorates. Therefore, we make no claims to predict future migration flows, but rather ask the question: “If climate were the only factor operating, how many people would we predict would want to migrate?” This might be some sort of strong upper bound on maximum likely migration flows.

We first regressed population density on a host of geographical factors (e.g., distance to rivers or the ocean) and also on climatic factors (e.g., temperature and precipitation). We then used climate model projections to estimate possible future climate conditions under different scenarios and then asked what was the ratio of the predicted population under the changed climate relative to the predicted population under the current climate. The departure of this ratio from the value of one, we took as an indicator of the fraction of population that would have incentive to migrate from (or immigrate to) a specific location.

Figure 1. Ratio of population predicted under RCP8.5 end-of-century projections divided by population predicted for current climate. The tropics are anticipated to be a region in which climate change may provide many people with an additional incentive to emigrate. (Chen and Caldeira, 2020)

This exercise predicts (Figure 1) that climate change would provide people living in much of the tropics an incentive to emigrate, and that the mid and higher latitudes, especially in the Northern Hemisphere, would be potential recipient regions for these migrants.

Figure 2. Number of people per grid cell projected to have additional incentive to migrate under RCP8.5 end-of-century projections. This map is the map in Figure 1 multiplied by a map of projected population. (Chen and Caldeira, 2020)

The number of people projected to have additional incentive to migrate (Figure 2) is calculated as the product of the climate-related factors shown in Figure 1 and a UN population projection.

Figure 1 shows that the Amazon might be place from which climate change would add incentive to emigrate, but relatively few people live in the Amazon, so the Amazon does not show up in Figure 2 as a region with many people with additional incentive to emigrate.

In contrast, India has a hot climate that is getting hotter, along with very high population densities, and so stands out as a place from which many people may potentially be incentivized to emigrate, showing up as red on both Figures 1 and 2.

Many people think that the RCP8.5 scenario featured in the figures above are unrealistic. (We include figures for other RCP scenarios in the Supporting Material.)

Figure 3. Scaling of number of people having incentive to migrate as a function of increase in global mean temperature relative to year 2005. (Chen and Caldeira, 2020)

Our results for number of people with additional incentive to migrate as a function of increase in global mean temperature relative to year 2005 across the range of RCP scenarios and time periods between now and the end of the century scale fairly linearly with global mean temperature change (Figure 3).

By year 2005, the world had warmed nearly 1 C relative to pre-industrial temperatures, and by now it has warmed more than 1 C. Our analysis suggests that warming to, say, 2 C above preindustrial values could provide more than 500 million people additional incentive to emigrate. Warmings of 3 C or more above preindustrial values could provide additional incentive-to-emigrate to well over a billion people.

Our “all other things equal” spherical-cow-type calculation indicates the large magnitudes of people for whom climate change may provide additional incentive to migrate (although they may have overwhelming incentives to remain where they are) . Therefore, only a small fraction of people with additional incentive to migrate might actually migrate.

I’d like to point out that many cities (Dubai, Houston, Las Vegas, etc) exist because the people there are relatively rich and can afford air conditioning.

And few people have starved to death with money in their pockets.

Rich people have greater capacity to migrate, but poor people tend to be more directly affected by weather and climate.

It is not the purpose of our study to try to predict real migration flows, but rather to do some simple analyses to indicate the possible scale of the issue.

Our analysis indicates that the potential scale is very large. Substantial effort will be required to produce an energy system that does not use the sky as a dumping ground for waste CO2, and thereby limit the amount of climate change. Further, substantial effort will be required to help develop economies that can deliver to people the things they need to live the most rewarding lives they can have.

The purpose of our paper is not to predict how many climate migrants there may be in the future, but rather to emphasize how important it is that we address climate and development issues in an integrated way, so that we protect our environment and create a world in which every child has the opportunity of living a rewarding and fulfilling life.

Comments on allocating resources to fusion-energy research and development

The following is based on a note written to a journalist asking for my opinion on funding for fusion research. Obviously, these are just my opinions …

History has shown us that experts are very bad at predicting technological winners and losers.

There are only a very small number of technologies that could potentially provide energy at the scale that civilization requires without severely damaging the environment, and fusion power is a member of that elite club. Therefore, some resources should be allocated to trying to make fusion power safe, abundant, and affordable.

While I am no expert on the matter, it seems to me that even if fusion could be made to work, it might turn out to be costly.  

In any case, the question should be: What fraction of the clean energy research and development budget should be allocated to fusion?

My sense is that 1% would be too small, and 100% would be too large, and so it maybe something to which it might be worth allocating 5 or 10% of the clean energy research and development budget.

And of course, it is not just about shares of the R&D pie. The clean energy R&D pie itself needs to be much larger than it is today.

We need to adopt a portfolio approach, with some investments yielding fruit over the next years and decades, and with other investments perhaps yielding fruit only later this century.

It is never too early or too late to develop improved sources of safe, abundant, and affordable energy. Sooner is better than later, but later is better than never.

We should avoid believing that we know with a high degree of confidence what will work and what will never work. We should have humility in our own judgments and think that we might be wrong — that this technology which we believe will never substantively contribute to solving societal problems might just turn out to be the thing upon which we all depend.

Therefore, we need to be thinking about broad research portfolios, while carefully evaluating each item in that portfolio in terms of potential benefits of research investment, balancing risks against rewards.

Environmental science of climate, carbon, and energy