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Dealing with the Climate Crisis

Anthony Day helps you plan a sustainable future with expert guests and reports on green technologies from across a warming world.

Pandora's Toolbox
ISBN 978-1-316-51843-4

Today we’re looking at the step beyond Net Zero: climate intervention or geo-engineering. Prior to his academic career, today’s interview guest had several executive roles in the aeronautical industry, including the presidency of a division of Boeing. He is a Senior Fellow at the Mossavar-Rahmani Center for Business and Government at the Harvard Kennedy School, and as a lecturer at Yale University teaches a world-leading undergraduate course on climate intervention. In his new book, he says,

“Geo-engineering in any form sounds like a terrible concept, until you peer carefully into the future and realise that not geo-engineering would likely prove worse.”


Today, I'm welcoming Wake Smith, the author of Pandora's Toolbox: The Hopes and Hazards of Climate Intervention. Wake, welcome to the Sustainable Futures Report.

Wake Smith:

I'm happy to be here, Anthony.

Net Zero


Great. Well, let's start off with net zero. Net zero is a big challenge and only this week, António Guterres, the United Nations Secretary general has said that if we start a rush to coal and other fossil fuels in the face of the crisis in Ukraine as we scrabble around for alternative sources of energy, we could put net zero completely out of reach. In fact, he also said that what was agreed at COP 26 in Glasgow at the end of last year was not enough to actually get us on the path to achieve net zero. But then I look at your book and you start off by saying net zero, that's just the start. So, where do we go from here?

Wake Smith:

Well, I am an emissions pathway pessimist, I should confess. And by that, what I mean is that I don't believe that the more optimistic emissions pathways that various climate cheerleaders would urge us to pursue, and I would urge us to pursue the same by the way, so maybe I shouldn't phrase it quite that way. But despite the extent to which the world would be a much better place if we got to net zero more quickly, I'm afraid that we are unlikely to get to net zero as quickly as need be and getting there quickly is essential if we're going to make the achievement of net zero the end of the climate crisis.

If we get to net zero quickly, by mid-century, say, then I think the crisis will have been averted and that will be the end of it. But if, instead we get to net zero at the end of this century or thereafter, then we will have grave problems and the achievement of net zero will not in and of itself solve those problems. So, you're quite right that I worry that late net zero will mean that net zero is not the end of the climate crisis.


Now the book talks about climate intervention, the ways of achieving net zero, you talk about a number of technologies and approaches, but you talk about their drawbacks as much as their advantages. So, let's look at some of those in detail. Should we start off with carbon recovery?

Wake Smith:

Sure. And to make sure that I'm going to answer the question that you've asked, we're talking about reducing emissions or capturing carbon from the air?


Let's just distinguish between those two, if you would.

Cumulative Emissions

Wake Smith:

Sure. So we must reduce our greenhouse gas emissions to net zero. And let me come back to net zero, but let me first explain why we have to get to zero of some sort. What informs the climate is not the amount of our emissions in any given year, it's the cumulative emissions since the beginning of the industrial revolution, approximately.

And a better way to think of it is a bathtub where we've got a spigot, a tub, and a drain. The spigot is our ongoing emissions. The tub holds the water and the analogy is the water in the tub is the concentration of greenhouse gas in the atmosphere. The problem is the drain is for all human purposes clogged. It flows but on a centennial or millennial timeframe. So, it's not until we cut the spigot flow all the way to zero that the water level in the bathtub stops rising, or again, the concentration of greenhouse gases in our atmosphere stops increasing, and it's that final level of greenhouse gases in the atmosphere that defines the future temperature.

So again, we don't need to reduce our emissions. We need to get at them all the way to zero before the water level in the bathtub stops filling and before therefore the climate continues to warm. And reducing by five or 10%, that's a very achievable thing. Reducing by 100%, that's very, very difficult,


Right. So, we've got to look at two aspects then. We've got to look at the way that we are adding CO2 emissions to the atmosphere. That's your spigot. And we've got to look to see if we can do anything about unplugging the drain and actually taking out some of the emissions, which are already in the atmosphere.

Net Zero 2050

Wake Smith:

All of that's exactly right. And back to the net zero point, if we get to net zero, say by mid-century, the projection is that would increase temperatures above the pre-industrial average by about one and a half degrees Celsius. It would increase temperatures from today's level by a mere four tenths of a degree Celsius, because we're already up 1.1 degrees. And so getting to net zero by mid-century would involve a bit more climate change, but only a bit.

Climate change is problematical now, but frankly, not very problematical. If you were to tell me that the climate level of climate change we have today is all we’re ever going to get, I would pop champagne. And a little bit more climate change, again, humanity could almost certainly adapt to that. But if instead, we're talking about climate temperature changes of three degrees Celsius, which is what an end of the century achievement of net zero would entail, that would be a very different order of magnitude of climate change and order of magnitude of climate damages. And so again, it's that higher level of climate change that I worry about.

Paris Agreement


It's been suggested in fact, that if we achieve our Paris targets from the Paris Agreement, that we will nevertheless still get to a three degree increase. So, we have got to do something and either we have got to take emissions out of the atmosphere, or we have got to stop adding to them. But there seems to be little sign that whatever we do or whatever we say or whatever governments commit to, there seems to be little sign of any reduction in the rate in which we are actually adding to the emissions in the atmosphere.

Wake Smith:

Well, you're quite right. The IPCC would urge that we in this very decade cut our emissions by approximately 5% a year, such that by 2030, we have cut them in half and have the next couple of decades to cut the remaining half, which will be the harder bit. In 2020, we did cut our emissions by a bit more than 5%, but that's because the economy was wrecked via a pandemic that no one planned for. In 2021 emissions snapped back nearly to their pre-pandemic levels, and the expectation as you know, is that in this year or the next in emissions will surpass the 2019 level.

Increasing Emissions

So, instead of cutting emissions dramatically, it appears that we are continuing to increase our emissions. And that isn't exactly because the world is immoral. There are forces that are perfectly valid forces that are pulling in the opposite direction, to the extent that the human population on the planet increases from the current 7.6 billion or so to 10 or 11 billion by the end of the century. All other things being equal a quarter or a third more people will mean a quarter or a third more demand for energy. And we can't say no to those newly born.

Moreover, the global south aspires to begin to live the energy rich lifestyle that we in the global north currently live. And there's no moral basis on which to tell them they can't do that. So, both population growth and economic growth, particularly in the global south, call for more demand for energy. And so the bits of the equation that we can move in the right direction, how much energy it takes to produce a dollar of income or a pound of income in the economy, and how much carbon is required to produce that energy, we've got to get those things going down faster than those earlier terms are going up. And the point is the history of the industrial world over the last 100 is that every year we lose that tug of war. Every year, the demand for energy and therefore the emissions is growing, unfortunately.

Climate Intervention


So, climate intervention. Is that a solution to the challenge?

Wake Smith:

It is a partial solution. So, there's a US climate journalist who's turned the phrase that there's no silver bullet here, there's merely silver buckshot. So, there will need to be lots of solutions that in the aggregate we hope will add up to a comprehensive solution. So, decarbonising our energy supply is absolutely essential and we've got to find a way to do that. PSU had earlier noted that the political disturbances in the world right now in Ukraine, make that a more remote goal, make that more difficult. Those will increase the degree to which countries emphasise energy security over emissions reductions and that will therefore delay net zero.

But we must one way or another decarbonise. We've got to be more efficient with the energy that we do need. But again, I worry that all of those things will likely not be enough to keep us on the 1.5 C track that would be a low problem track. Rather, if we're on a 3C type of track, then once we get to net zero, the water level in our bathtub will likely be unacceptably high to the people alive at that time.

Cleaning Up the Atmosphere

And so in addition to stopping the spigot, they will indeed, as you earlier noted, want to widen the drain and therefore hasten the drain of greenhouse gases, principally carbon dioxide, out of the atmosphere. And the way to do that is direct air capture and sequestration, which is to say vacuuming carbon out of the atmosphere and burying it deep in the Earth's crust, where ironically, we got it from when we drilled for oil or dug for coal. But that reversal, that cleaning up of the toxic waste dump that we have made of our atmosphere, I'm afraid that will be the climate challenge of the next century so long as we in this century finally rise to our climate challenge and stop emissions.

$4.1 trillion


You talk in the book about direct air capture, but you also talk about carbon capture and storage in terms of capturing the carbon emissions from industrial operations, factories, power stations, and gas processing plants, and so on. Now, that alone, you identify as being phenomenally expensive. You quote a figure of $4.1 trillion for carbon capture and storage and you point out that will be required every year and that's equivalent to 5% of the global economy or 20% of the US economy. And maybe we could fund it by doubling the cost of petrol and fuels like that. But those are mind boggling figures. Is it really practical consider that sort of solution?

Wake Smith:

Well, currently no. If we hold a vote on that, the vote will be 99 to one and the one was confused about what the question was. Nobody's going to vote for that because it would be ruinously expensive and yet I'm afraid that people alive a century from now may feel that they have no choice, but to undertake that degree of cost in order to try to return, a century or two thereafter, the world to a climate level that is acceptable to their successors on the planet.

Carbon Debt

So, no, we are likely to leave our great-grandchildren with an unacceptably high carbon debt that nonetheless they're going to likely decide they need to redeem at a ruinous expense. So, none of it is a good trajectory and the expense of it is why it's so difficult to commence down this path. Right now, the climate is fine. I was just outside earlier today, it was lovely. So, I'm not feeling any climate pain. And do I therefore want to undertake that degree of expenditure for something that produces no currently useful economic product? Of course, I don't.



If this then might not be an issue for us, but might not be an issue until the time of our great grandchildren, surely there is time for the industries and so on which emit these greenhouse gases to be re-engineered so that in, say 50 years time, the amount of emission is much lower.

Wake Smith:

You would hope that is true. And yet I imagine that you and I are both standing on the deck of the Titanic on a very dark night and we now can see the iceberg clearly in front of us, but we somehow can't get the ship to respond to the rudder and the ship to swerve away from the iceberg. So we're chugging at full speed towards an iceberg we can clearly see and it has all the appearances that we're going to ram right into it.

50 years is a lot of time for you and I, and I personally plan to be dead before then. So, none of this is a problem for me, but, but I'm afraid that the world economy is that Titanic chugging away on primarily fossil fuels towards a disaster that we can clearly foresee and 50 years to divert the entire world economy away from the fossil fuels that still today are 80% of our energy demand, all in a context when energy demand continues to grow for reasons we've earlier discussed, that actually seems like a very hard challenge, not a challenge for which we've got loads of ample time.

Is it Worth It?


Are you saying it's not worth then going ahead with climate intervention? You have described carbon capture and storage. You've spoken about, and I think dismissed, bio energy and carbon capture and storage. We've spoken about direct air carbon capture and sequestration. You also in the book, you mention solar radiation management, which covers things like painting roofs white and so on.

But the big thing that you've picked up on is stratospheric aerosol injection, which you say would have a very rapid effect. You say that we are not ready to do it yet and you wouldn't press the button if somebody said it's available now. But subject to adequate research. Is that something you think we should be considering?

Decarbonisation Imperative

Wake Smith:

Well, yes, but let me first cycle back to a statement you made at the outset of your phrases there. Despite the fact that decarbonisation will be difficult, we absolutely have to do it. There's only one door that leads to an acceptable climate, and we've got to go through that door and that door is decarbonisation. I'm afraid though that we won't do it soon enough and so we are also going to need to engage in carbon capture. That too has a lot of problems related primarily to the expense and the energy requirements. And yet there too, I'm afraid we will leave the future with no choice. So, the fact that these are problematical choices doesn't mean we shouldn't do them. We have to engage in aggressive mitigation, which is to say reduction and elimination of our emissions. And we will likely have to engage thereafter in carbon capture, extremely expensive though it may be.

But the pace of carbon capture is another thing that people need to wrap their heads around. Even if we did get to a point, we, the world in a century, get to the point where it's willing to recapture carbon from the atmosphere and bury it in the Earth's crust at very high expense, that process may take a century or two to undertake. After all, it will have taken us a couple of centuries to have put that greenhouse gas into the atmosphere.

And so if we remove it at a pace similar to that with which we deployed it, that's a couple of century type exercise. If it is too hot for the people who are living through that exercise and paying for it, they may ask themselves, well, what can we do to cool the climate quickly? It's too hot.

And again, this isn't too hot like I'm a little sweaty. So, if it gets in that future time, too hot for the people living in that time, in addition to undertaking carbon capture, they may seek a more rapid solution to the climate problem that they're living in. And that more rapid solution is to operate on the other side of the energy equation. The problem with all these emissions we've put into the atmosphere is that they prevent heat from escaping from the earth.

Solar Radiation Management

So, sunlight comes into the Earth and heats the earth up, and then the Earth gets hot and like a radiator, it radiates that heat out. The greenhouse gases in the atmosphere act like a blanket and prevent some of that radiation from going out. So, if we can't widen the drain, allow more heat to leave the earth quickly, the other side of the climate equation would be to cause less sunlight to come into the climate system, and that's solar radiation management.

As you've earlier noted, we might be able to do a little of that by painting roofs white or by modifying crops to be a little bit lighter in color or modifying clouds to be a little bit brighter and reflect more sunlight. But frankly, I don't currently have a lot of faith in any of those solutions because of the scale at which we've got to do them. We've got to reduce one or 2% of the incoming sunlight on the entire Earth and painting roofs in cities white won't move that dial much at all.

Stratospheric Aerosol Injections

The one thing that we currently envision that could move the meter substantially and quickly and incredibly cheaply is, as you've earlier noted, stratospheric aerosol injections. And that is the idea of deploying into the lower stratosphere reflective aerosol particles that would deflect out one or 2% of the incoming sunlight and thereby balance Earth's energy budget in that way. Less energy leaving because of the greenhouse gas concentrations. But less energy coming in because of the reflective aerosols.

And based on all that we currently understand about that, it looks like it would work and work fairly easily, but, big caveats, there's been no field research on this, not a single experiment outside the lab. And so we don't currently have a good understanding of what bad stuff it may do. It may turn out while volcanoes demonstrate to us that this does work because they blow into the atmosphere the exact same material that we would likely start with, it may be that doing this continuously, because it would need to be continuous for decades or a century perhaps, it may be that doing this continuously has bad physical impacts that we don't now anticipate.

 Policy Decisions

And so there's lots of field research that would be necessary before it would be a prudent scientific decision to go ahead with this. Moreover, scientists won't make that decision. It's policymaker who will make that decision and how we would govern a global intervention into the climate system that would affect every living thing, I just have no idea how we would create a structure that would lend legitimacy to such an exercise. So, we think it would likely work. We think it would likely be feasible. But what bad stuff might come of it and how we would govern it? Those questions are completely unanswered.


That anticipates my next question, which was going to be about the political aspect. Because there is the possibility, and as you say, there's no field research, so we don't know, but there is the possibility that if we did something into the atmosphere, it could change the weather patterns. Some countries would be affected beneficially. Others could be affected in a bad way. And even if we got a consensus to start a project like this, we might very quickly fall out and decide to stop it. So, it's a question. Everything seems to be problematical. You look at all the known and proposed technologies for climate intervention, and you do find disadvantages with them all, I'm afraid, don't you?

Wake Smith:

I'm afraid that is true. I have named the book Pandora's Toolbox to signal in the very first word that this isn't a bowl of cherries, but I'm afraid that the world is naively optimistic about how easy it will be and how quickly it can be done to solve the climate problem. And the world is also optimistic that somebody else will have to pay for it. The world is not yet prepared for the realisation that we ourselves will pay for it in terms of increased prices for things and therefore lower standard of living. But the sooner we bite that bullet, the lesser the problem will be for future generations. But we are air-mailing to the future a big can of worms.



I generally conclude my interviews by asking my guests, if they're optimistic. Well, I have to ask you that as well. But I think you've told us that, well, it's very difficult to be optimistic.

Wake Smith:

Yes and no. Today is a lovely day. Ukraine aside, my world is okay. Much of the world is okay. There are forward steps we can take on the climate problem. And so long as there are possible forward steps, then there is hope. Humanity is exceedingly clever and innovative. And so it must be that we will find ways through these problems. And it must be that technological interventions, which will come along, that will make them easier, or at least one can hope that is so.

 Not the End of Civilisation

I don't think that this will be the end of civilisation. I'm still much more worried about nuclear weapons than I am about the world ending because of climate change. So, I wouldn't phrase it in those ways. But again, that doesn't mean that it isn't a problem. It's a big problem and it's a bigger problem than most people realise. So, am I optimistic? Well, I'm optimistic that I can add my light to the sum of light and maybe thereby make it a little lighter.


Well, thank you very much for that. Just before we close, can we just remind ourselves of the story of Pandora and why you chose that as the title for the book?


Wake Smith:

So, Pandora, to keep the story short, receives a box of unknown things that she's not meant to open. She, of course, is overwhelmed by curiosity and does open the box and out of the box leap all of the evils of the world. But out of the box, or in fact within the box at the end, nonetheless is one gift, and that gift is hope.



Well, thank you very much. Thank you for leaving us with some hope. Wake Smith, thank you very much for talking to the Sustainable Futures Report.

Wake Smith:

Very kind of you to have me. It's been fun.


The book Pandora's Toolbox: The Hopes and Hazards of Climate Intervention is out now. ISBN 978-1-316-51843-4


And now I’m delighted to welcome our latest Silver Supporter. Jane White joins the increasing number of listeners down there in Australia. Jane, welcome. Jane and her fellow patrons at keep the Sustainable Futures Report independent and ad-free. Your support is much appreciated.

That was the Wednesday Interview from the Sustainable Futures Report.

There will be another Sustainable Futures Report on Friday.

I’m Anthony Day.

Until next time.



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A weekly podcast and blog brought to you by Anthony Day. A selection of stories and interviews aiming to be sustainable, topical and interesting.
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