The only argument against [nuclear energy] is a political one, that people won’t accept it, or people won’t want it. I don’t think there are any engineering or physics challenges that can’t be fairly easily addressed, and that includes the cost.

Mark Lynas

A golf-ball sized lump of uranium can deliver more than enough power to cover all your lifetime energy use. To get the same energy from coal, you’d need 3,200 tonnes of the stuff — a mass equivalent to 800 adult elephants, which would go on to produce more than 11,000 tonnes of CO2. That’s about 11,000 tonnes more than the uranium.

Many people aren’t comfortable with the danger posed by nuclear power. But given the climatic stakes, it’s worth asking: Just how much more dangerous is it compared to fossil fuels?

According to today’s guest, Mark Lynas — author of Six Degrees: Our Future on a Hotter Planet (winner of the prestigious Royal Society Prizes for Science Books) and Nuclear 2.0. — it’s actually much, much safer.

Climatologists James Hansen and Pushker Kharecha calculated that the use of nuclear power between 1971 and 2009 avoided the premature deaths of 1.84 million people by preventing air pollution from burning coal.

What about radiation or nuclear disasters? According to Our World In Data, in generating a given amount of electricity, nuclear, wind, and solar all cause about the same number of deaths — and it’s a tiny number.

So what’s going on? Why isn’t everyone demanding a massive scale-up of nuclear energy to save lives and stop climate change? Mark and many other activists believe that unchecked climate change will result in the collapse of human civilization, so the stakes could not be higher.

Mark says that many environmentalists — including him — simply grew up with anti-nuclear attitudes all around them (possibly stemming from a widespread conflation of nuclear weapons and nuclear energy) and haven’t thought to question them.

But he thinks that once you believe in a climate emergency, you have to rethink your opposition to nuclear energy.

At 80,000 Hours we haven’t analysed the merits and flaws of the case for nuclear energy — especially compared to wind and solar paired with gas, hydro, or battery power to handle intermittency — but Mark is convinced.

He says it comes down to physics: Nuclear power is just so much denser.

We need to find an energy source that provides carbon-free power to ~10 billion people, and we need to do it while humanity is doubling or tripling its energy demand (or more).

How do you do that without destroying the world’s ecology? Mark thinks that nuclear is the only way:

“Coal is a brilliant way to run industry and to generate power, apart from a few million dead every year from particulate pollution, and small things like that.

But uranium is something like a million times more energy dense than hydrocarbons, so you can power whole countries with a few tons of the stuff, and the material flows and the waste flows are simply trivial in comparison, and raise no significant environmental challenges — or, indeed, engineering challenges.

It’s just doable, and it isn’t doable with any other approach that you can imagine.

Renewables are not energy dense, so you have to cover immense areas of land to capture enough solar power through photovoltaic technology to even go a small distance towards addressing our current energy consumption with solar. And wind likewise.”

How much land? In Nuclear 2.0 Mark says that if you wanted to reach the ambitious Greenpeace scenario for 2030 of wind power generating 22 percent of global electricity and solar power generating 17 percent, wind farms would cover about 1 million square kilometers. That’s about as much as Texas and New Mexico combined. Solar power plants would cover another ~50,000 square kilometers.

For Mark, the only argument against nuclear power is a political one — that people won’t want or accept it.

He says that he knows people in all kinds of mainstream environmental groups — such as Greenpeace — who agree that nuclear must be a vital part of any plan to solve climate change. But, because they think they’ll be ostracized if they speak up, they keep their mouths shut.

Mark thinks this willingness to indulge beliefs that contradict scientific evidence stands in the way of actually addressing climate change, and so he’s aiming to build a movement of folks who are out and proud about their support for nuclear energy.

This is just one topic of many in today’s interview. Arden, Rob, and Mark also discuss:

  • At what degrees of warming does societal collapse become likely
  • Whether climate change could lead to human extinction
  • What environmentalists are getting wrong about climate change
  • Why political and grassroots activism is important for fighting climate change
  • The most worrying climatic feedback loops
  • And much more

Get this episode by subscribing to our podcast on the world’s most pressing problems and how to solve them: type 80,000 Hours into your podcasting app. Or read the transcript below.

Producer: Keiran Harris.
Audio mastering: Ben Cordell.
Transcriptions: Zakee Ulhaq.


Our Final Warning

I conceived and wrote [the book] actually as a big, giant spreadsheet really, where I’m putting together everything in the climate impact literature and attaching it to the relevant degrees of warming. So I can answer the question of what happens at two degrees. Actually, what happens at one degree is what we’re seeing around us. Because we’re already in the one degree world. So we can talk a bit more about that. And also just to tell the story of what happens if global warming continues to accelerate, and then we don’t succeed in mitigating it. And if we go rocketing past two degrees, even three degrees, where we end up and what kind of world we would be inhabiting then.

So you mentioned four to six degrees. This is a world where it becomes too hot biologically for humans to survive in substantial parts of the tropics and subtropics. So North Africa, the Middle East, South Asia. So that’s India, Pakistan, Bangladesh, parts of China, Indonesia which, coincidentally, all these areas host the majority of the world’s population currently. And it would be biologically intolerable. Basically, we’ve begun to make a large area of our most populated area of our planet uninhabitable. And then at the same time, we’d lose a lot of food production, again, because crops can’t survive either in this kind of heat and also the drought associated along with it. But we’d long since have lost the Arctic ocean ice cap, most of the world’s mountain glaciers, and a good proportion of the species that currently exist on the planet alongside us. So it would be well into a geologically defined ‘mass extinction’.

The most useful things that humanity has done to reduce climate change so far

The invention of nuclear fission was probably a key one. It wasn’t intended for that. Obviously it was intended to make bombs initially, and then was intended to make electricity. And was always seen as being environmentally terrible. It turns out that’s not the case and that will, and I’m sure we can talk about this, require an ideological mind shift amongst environmentalists more than anyone.

But we have made great strides with renewables. Bringing down the cost of solar panels means that solar is now probably the cheapest technology in most developing countries, which means you can get quite rapidly to zero carbon electricity in many places that don’t even have access to modern energy at the moment, which is great.

We’ve got lithium ion batteries which allow the electrification of a lot of transport. I’ve got an electric car. That wouldn’t have been possible even two or three years ago to get the mileage that it’s now delivering. And so you can sort of see the contours of a post-carbon landscape, which wasn’t the case when I started out. You had to just believe and hope that things would be invented, which now look like they can be part of the solution.

Worst case scenarios

I remember when some spokespeople were in the media saying, “Billions are going to die in the next 10 years.” And I think it was Andrew Neil actually might be, who in the interview said, “Well, how? What’s going to happen that’ll kill all these people?” And they weren’t able to answer.

So it’s one thing to have an apocalyptic fear and another to actually try and think through what the mechanisms are which would actually kill people if that’s what you’re concerned about. What kills people? Thirst kills people. War kills people. Anger kills people. People die because of lack of shelter.

So it’s different degrees of civilisational collapse. I mean, conflict/war is a civilisational collapse in a way, particularly if it’s essentially worldwide. So to me, I think the most concerning scenario is one where you can’t produce enough food to sustain the world’s population, which is a lot higher. We learned that by 2050, the latest UN figures are 9.7 billion by 2050. But you have to have pretty much doubled the world’s food supply at the same time, as you’ve got less and less of the world’s land being able to produce because of the combined impacts of heat and drought. And obviously, plants can’t grow without water. Lots of plants can’t grow if it’s too hot.

Arguments against nuclear energy

The only argument against is a political one, that people won’t accept it, or people won’t want it, so nothing to do with engineering. I don’t think there are any engineering or physics challenges that can’t be fairly easily addressed, and that includes the cost. Yeah, nuclear is very expensive at the moment, but that’s because it’s trying to satisfy safety concerns, which are taken vastly more seriously than any other type of infrastructure projects, and therefore require multiple redundant safety approaches, which cost a huge amount. You’ve got to build, I think, the EPR reactor at Hinkley… They talk about it’s like building a cathedral inside a cathedral. That’s the kind of engineering which we’re left with to try to reassure the public that this isn’t an existential threat. What’s that? That’s not engineering. It’s a psychological challenge. It’s a political challenge. The only way that I think it’s wrong is if people won’t accept it, and we waste time trying to do it instead of simply paving over whole countries with solar panels, if that’s the only way that’s mostly acceptable.

No one in the nuclear industry would ever say “Let’s save costs by reducing our safety components”. But those of us who are not in the industry can say, “Well, look. Why is it that nuclear has to fulfill this safety concern vastly more than anything else?” Cars aren’t that safe. Nothing’s that safe.

Not only coal, but even wind and solar aren’t that safe in terms of numbers of fatality per gigawatt hour, or however you want to quantify it. People fall off roofs putting solar panels on, and wind turbines fall apart and whatever, so nothing’s completely safe. Even in the worst case scenario, nuclear accidents, at least with the type of technologies we’re using, I wouldn’t use Chernobyl because that’s not the kind of reactor that we’ve got built anywhere else. But say Fukushima in Japan, which was about the worst, like a triple meltdown in the context of a much wider natural disaster, that’s about as bad as it can get. How many people died from radiation? Zero. That’s not even on the same scale as Piper Alpha, where the oil rig blew up and killed 150 people, or any mid-range industrial accident.


If you want to be in a situation where food crops can still grow in a hotter, drier environment, you’re going to have to change their genetics. How are you going to change their genetics? Well, you’ll need to use genetic engineering. This isn’t complicated for people who understand. And so, yes, GMOs maybe could buy us a decade or two in terms of avoiding the supply shortages that might otherwise arise from low to moderate levels of warming. And also they can make, and are making agriculture more sustainable. If you’ve got insect repellent crops which fend off insect attacks, then you don’t need to spray them with insecticides.

There are crops which are disease resistant. So in Uganda, where I was a few years ago, they’ve got a big problem with bacterial wilt in the staple banana crop. There’s GMO varieties of banana already beyond the lab. They’re already in field trials, which could solve that problem basically. But because their GMOs, you’ve got this huge fear mongering campaign which is fully supported by Western aid agencies and NGOs, which has basically blocked up the political process in Uganda so that they probably won’t ever be released. Well done Westerners. You managed to stop Ugandans having disease-resistant bananas. Big round of applause for everyone, I think.

Articles, books, and other media discussed in the show

80,000 Hours problem profile on climate change (extreme risks)

Mark’s work

Everything else

Related episodes

About the show

The 80,000 Hours Podcast features unusually in-depth conversations about the world's most pressing problems and how you can use your career to solve them. We invite guests pursuing a wide range of career paths — from academics and activists to entrepreneurs and policymakers — to analyse the case for and against working on different issues and which approaches are best for solving them.

The 80,000 Hours Podcast is produced and edited by Keiran Harris. Get in touch with feedback or guest suggestions by emailing [email protected].

What should I listen to first?

We've carefully selected 10 episodes we think it could make sense to listen to first, on a separate podcast feed:

Check out 'Effective Altruism: An Introduction'

Subscribe here, or anywhere you get podcasts:

If you're new, see the podcast homepage for ideas on where to start, or browse our full episode archive.