A golf-ball sized lump of uranium can deliver more than enough power to cover all of your lifetime energy use. To get the same energy from coal, you’d need 3,200 tonnes of black rock — a mass equivalent to 800 adult elephants, which would 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 avoiding 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 conflation of nuclear weapons and nuclear energy) and haven't thought to question them.

But he thinks that once you believe in the 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 (or more) its energy demand.

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

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 fully addressing climate change, and so he’s helping to build a movement of folks who are out and proud about their support for nuclear energy.

This is only 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

• And much more.

Audio mastering: Ben Cordell.

Transcriptions: Zakee Ulhaq.