A decade ago, I was feeling pretty pessimistic about climate change. The politics of mitigating global warming just seemed impossible: asking people to make sacrifices, or countries to slow their development, and delay dreams of better, more prosperous lives.

But the world today looks different. The costs of solar and wind power have plummeted. Same for electric batteries. And a new politics is starting to take hold: that maybe we can invest and invent and build our way out of this crisis. But some very hard problems remain. Chief among them? Cows.

Hannah Ritchie is the deputy editor and lead researcher at Our World in Data and the author of “Not the End of the World: How We Can Be the First Generation to Build a Sustainable Planet.” She’s pored over the data on this question and has come away more optimistic than many. “It’s just not true that we’ve had these solutions just sitting there ready to build for decades and decades, and we just haven’t done anything,” she told me. “We’re in a fundamentally different position going forward.”

In this conversation, we discuss whether sustainability without sacrifice is truly possible. How much progress have we made so far? What gives her the most hope? And what are the biggest obstacles?

I think one of the questions on which our whole future hinges is whether the lives that we have, the lives that we want, can exist within our environmental limits. Is there a way to live lives as energetically rich, as materially prosperous as Americans do now, without doing irreparable damage to the world? Is there a way for people all over to live lives even better than Americans do without doing irreparable damage to the world? Can we decouple material prosperity from the environment?

And the politics of sacrifice, they’re abysmal. They’re really hard, particularly the speed at which we need to act on climate. You try passing a global carbon tax and enforcing it. You try doing energetic redistribution between rich and poor countries. You try banning, god forbid, hamburgers.

But if you can marry prosperity to sustainability, if we can power the lives we want with clean energy, if we can feed the world without wrecking every ecosystem in our sight, then we have the politics of transition. And the politics of transition is hard. Deployment is hard. Change is hard. But it is more imaginable.

And maybe you can even promise that things get better too, that we get cleaner air, healthier food, regenerated forests. That’s a bet a lot of the climate movement is now making. It’s a bet most countries are now making. But is it possible or is it just a fantasy? Do we actually have the critical minerals, the land, the technology?

That’s a question that Hannah Ritchie, the lead researcher at Our World in Date, set out to answer in a book “Not the End of the World.” It’s a question that obsesses me, so I asked her to come on the show to talk about it.

Hannah Ritchie, welcome to the show.

HANNAH RITCHIE: Thanks very much for having me.

EZRA KLEIN: I’ve heard you say something that has stuck in my mind, which is that air pollution is a problem of energy poverty. What do you mean by that?

HANNAH RITCHIE: So air pollution is generated when we burn stuff. And I think when people think of burning stuff they automatically think of burning fossil fuels, which is absolutely correct. But we also generate air pollution when we burn wood, or charcoal, or crop waste, or dung, which many people in the world, especially the poorest people in the world, rely on as their main energy source. So I think if you see images of Lahore or New Delhi in the U.S. we think, oh, my god, the levels of pollution there.

But go back less than a century and that’s what — I mean, I’m in Edinburgh in Scotland. That’s what Edinburgh looked like. That’s what London looked like. That’s probably what New York looked like. It’s just that we are now further along the curve of pollution than many of these cities.

What we tend to find is that air pollution follows what we call the Environmental Kuznets Curve. So if you imagine a graph, and on the y-axis, you have air pollution, and on the x-axis you have G.D.P. or income or wealth. What you tend to see is this upside down U-shape. So at very, very low incomes outdoor air pollution, for example, can be relatively low.

EZRA KLEIN: Or, it should be said, they don’t always have a choice.

HANNAH RITCHIE: Or they don’t have a choice, yes. If they don’t have alternatives and fossil fuels is the only option they have, millions of people die simply because they do not even have access to fossil fuels. They’re stuck on wood or charcoal.

EZRA KLEIN: What’s the death toll of air pollution annually?

HANNAH RITCHIE: So there are a range of estimates. All of the estimates are in the millions. I mean, the W.H.O., the World Health Organization, has a figure of around 7 million every year, and around 57 million people die every year. It was slightly higher during Covid. If you take 57 million and you say 7 million are dying from air pollution, you’re talking about more than 10 percent of deaths can be attributed in some way to air pollution.

EZRA KLEIN: I want to zoom in on something happening on the part where the curve begins to slope down as the country gets richer. Because one way of thinking about air pollution, but a lot of environmental problems, is it to get less of the bad thing you need less of the good thing. To get less air pollution you need less industry. To get less air pollution you need fewer cars.

But to use the example of the United States, we have many more cars today than we had in 1970 or 1975. But the air in 1975 was much worse than it is today. You go to California, you go to Los Angeles, where I grew up — I mean, the smog that would settle over L.A. was legendary.

HANNAH RITCHIE: Yeah. So you’ve got two options. You can do less stuff, as you say, or you can improve the technologies so you can get the same stuff just with less pollution or less externalities. And there are a couple of key innovations here. I think that your example of cars is absolutely correct. There just have been massive developments in the reduction in pollution from cars.

And that’s a combination of, one, policy controls, so forcing manufacturers to develop cars that emit less. But it’s also about then the technological innovation that comes from that kind of forced policy setting. And industrial sites, for example, a big issue across Europe and North America which has basically gone was acid rain.

And there the problem was sulfur dioxide. So when we burn coal, you produce sulfur dioxide. And that was leaking out into the environment and causing acid rain. Emissions of sulfur dioxide have plummeted. And there again, there were two ways to do that. One, you could just stop burning coal. And, to some extent, that transition has happened. But another big innovation there is that we just developed a technology called a scrubber, or desulfurization technology that you could literally just put in the smokestack of the coal plant and take the sulfur out.

That needed some push from government policy to force that innovation. And then it needed some investment to get there. But that was the flip side of the coin of you don’t need to just necessarily do less. You can develop technologies that can do better.

HANNAH RITCHIE: No, I don’t think that’s really the case with air pollution. Yes, the U.K. and the U.S. have reduced levels of air pollution, but so has China. So it cannot possibly be the case that we’re just offshoring all of the pollution to China if China’s pollution is also falling rapidly. And it has fallen rapidly. Especially over the last decade, local air pollution in cities like Beijing and other major cities across China have really plummeted with massive health benefits for those populations.

EZRA KLEIN: To just add some numbers to that — because I think they’re really striking — in Beijing air pollution fell by 55 percent between 2013 and 2020. The number you have in the book for China as a whole is 40 percent. So how did they do that? What is happening that China could make air pollution fall so much faster than other countries have been able to do it in the past?

HANNAH RITCHIE: So this was really kick started by the 2008 Beijing Olympics. Pre-2008, if you were to ask someone, picture a city with really high levels of air pollution, they’d probably picture Beijing. And the world was descending on Beijing for the Olympics. The top athletes in the world were coming to the city, and all eyes were on Beijing.

The Chinese government realized we can’t have this horrendously polluted city. We need to clean this up for the athletes that are coming in. And it was still one of the most polluted Olympics ever, but emissions and levels of air pollution were much lower than they were pre-Olympics. The problem is that when all the athletes went home and all of the eyes turned away, the pollution levels came back. It was a very short-term reduction in order to facilitate the Olympics.

And it was really this public pressure that kickstarted action on concerted reductions in levels of air pollution. A key one has been really strict reduction in coal burning in households, for example, which you would imagine in Edinburgh or London a century ago, as well. It’s the same in China, where people were using coal in cities to heat their homes.

And there was a really strict crackdown on that, in some sense too strict, such that some households were temporarily left without energy. A shifting of industry outside of the city — the problem is that often you’ll have industrial sites very, very close to dense population centers. So you can move those industrial sites further out where there are less people. And then strict industrial controls — and in China, strict regulation can be put in place very, very quickly. And actually, industries do take action very quickly.

EZRA KLEIN: How much is the rapidity of what China was able to do because we simply have more ways to generate energy in 2024 than we did in 1904 without burning things? We have nuclear energy. We have solar energy. We have wind energy. We have advanced battery technology. How much is that an enabler of the possibilities here?

HANNAH RITCHIE: I think for China, in the last decade it hasn’t been — that contribution hasn’t been massive. Now, to be clear, China is rolling out renewable energies very, very, very quickly. It’s rolling out electric cars extremely quickly. But it’s still burning more coal than it was a decade ago. But as I say, going forward — and I think, for many other countries, this opportunity to skip a lot of the burning stuff phase of energy and moving straight to energy technologies where you don’t burn stuff is a massive opportunity to avoid the really high emissions and high polluting pathway that most countries have now been through.

EZRA KLEIN: One reason I really like the air pollution chapter in your book is that it sort of operates, I think, as a metaphor, which is this thing we did with air pollution, this thing we keep doing with air pollution, where we were able to bring it sharply down — the air in London, as you say, might be cleaner now than it has been in centuries. Is that possible for other kinds of environmental harm?

Because I do think there is this question that sits in people’s minds of whether the materially rich lives that we live in richer countries today is possible for the planet without completely cooking it. And one of the ways you look at this is by comparing your carbon footprint to that of your grandparents. And it’s a kind of surprising comparison. So can you walk me through that?

HANNAH RITCHIE: Yeah. So if you look at the carbon footprint of the average person in the U.K. over time, what you see is that over the last few decades, emissions in the U.K. have fallen really sharply. So since 1990, they’ve fallen by around 50 percent. The pushback on that is always, well, we’ve only achieved that because we’ve offshored emissions to other countries. And that’s not a genuine reduction.

Now, it’s completely true that the U.K. has offshored some of its emissions. But even when you account for that, and you account for that based on what we call consumption-based emissions — so it tries to adjust for the goods and services that the U.K. is buying and importing, and allocates those emissions to the U.K. rather than China, for example — what you find is that emissions are still falling, and still falling pretty quickly.

And if you look at pre-Paris Agreement — so Paris Agreement 2015 — the course that we were talking about the world heading towards then was 4 to 5 degrees. And that was just completely catastrophic. That’s not really the pathway that we think we’re on anymore. We’re kind of on track for between 2.5 to 3 degrees. Now, to be clear, that’s not an acceptable. We do not want to be on a path towards 2.5 degrees. But it is vastly different from a world of 4 degrees. We’ve chopped off a degree of that trajectory, at least a degree of that trajectory that we thought we were on.

EZRA KLEIN: The point you make that I found somewhat revelatory, even though it makes total sense now that I think about it, is that actually as you get into higher numbers, as we hit 1.5 degrees, if we hit 2 degrees, that every tenth of a point after that becomes more, not less consequential. Can you talk through that idea of the increasing marginal value of reducing climate change?

HANNAH RITCHIE: Yeah. So we know that the impacts of climate change — and by that I mean the impact that temperature has on stuff like precipitation patterns, for example — does not scale linearly with warming. So going from 1.5 degrees to 2 degrees is worse than going from 1 degree to 1.5 degree. So as we get into these higher and higher temperature ranges, we expect that the impacts will not be linear and they will scale much more quickly, which means that our emphasis to keep temperatures as low as possible increases the higher the temperatures go.

We also risk hitting feedback loops, or to some extent tipping points, which can amplify warming. And the words tipping points are kind of thrown around quite freely. And often people don’t define them very clearly. Here, I’m not necessarily talking about really large planetary scale tipping points that somehow flip us from one system into another. I’m often talking about more localized tipping points that we know exist in the system but don’t know exactly where they are.

Now, that’s not going to have a massive impact on the global climate system. But it could increase our warming by, I don’t know, the estimate’s about 0.15 degrees. Now, if you had several of these feedback loops or tipping points, again you might not go from 2 degrees to 5 degrees. But you could very easily increase the temperature by 0.2 degrees, 0.3 degrees, 0.4 degrees, which means that if you are at a temperature of 1.8 degrees, you’re then shifted into a world of 2.2 degrees.

And I think the key point here is that we don’t know exactly where these tipping points are. But some of them are potentially in that 1.5 to 2 degree range. And you’d certainly massively increase the risk of hitting them, the higher you are and closer you are to 2 degrees. So that’s why going from 1.8 to 2 degrees is much more consequential than going from 1.3 to 1.5.

EZRA KLEIN: I was struck reading through your book how much the solutions or the ameliorating policies seem to stretch across problem areas. I mean, it seems to me basically you’re talking about really two things over and over and over again, which is don’t burn so much stuff, and try to reduce the human footprint over land. And if you could get those two things more or less right, we could be in a much better place.

That’s a question of political will, and organization, and cooperation. And it is an extraordinarily hard question, as we’ve talked about and as everybody knows. But it is not an unsolvable problem. It is a set of choices we make or we do not make.

So if you’re talking about energy, for example, we’re in a vastly different position from where we were a decade ago. Because it’s not just about tackling climate change or tackling air pollution. It’s also about energy security. It’s about having lower energy bills. It’s about having more localized energy systems, which makes me more optimistic that they become viable and accelerate.

When people think about the vast array of environmental problems that we face, they get really overwhelmed. And they get really overwhelmed because they assume there are 50 solutions to 10 different problems, and therefore we need to find a way of implementing 500 different solutions.

And as you say, the reality is that when you bring it down to the basics we need to stop burning stuff for energy. And we need to find a way of feeding people on much less land. And I think we are getting closer and closer to the solutions we need, and the solutions are getting better and better for us to do that every year.

EZRA KLEIN: One of the most common questions I just hear at all is whether it is possible for all these different countries to be powered by clean energy sources — renewables, nuclear. And we know there’s a lot of solar power. Right? The sun is big and it keeps shining. We know there’s a fair amount of wind. But other things are limiting factors — the number of minerals we have to create solar panels with. You’ve got to mine all this lithium and mine all this cobalt to get your batteries.

As a matter of material, as a matter of how much the Earth has to give us, can we do what we need to do? Can we live and have more people living the kinds of lifestyles we see in the U.K., in the U.S., built on a clean energy foundation?

HANNAH RITCHIE: So there are a large number of researchers and different research organizations that have studied this question. And the answer that comes out is nearly always, yes, we have enough stuff. This has been said by the International Energy Agency. This has been said by Bloomberg New Energy Finance, by the Payne Institute.

There was a recent paper by Seaver Wang and Zeke Hausfather and colleagues, where they looked at the mineral requirements specifically on low carbon electricity globally. And the resounding answer was there are almost no minerals where total amount is a constraint.

What people also underestimate is that the amount of stuff we have or think we can extract tends to go up over time. And that’s because we find new deposits. We find new ways of extracting stuff that we couldn’t extract before. And actually, just the drive for low carbon energy will just increase our efforts in order to do that.

The other key change there goes in the other direction, where we’re becoming much more material efficient about building this stuff. The amount of materials you need to build a solar panel today is not what it was a decade ago. For many of these minerals you need far, far less. So our amount of supplies are going to go up, and our material requirements are probably going to go down. So if we were looking into the future, I’m just not concerned about total material requirements.

Are people right to be suspicious that the mining we’re going to need, the intensity of getting the Earth to give up what it needs to give up if we’re going to have all these solar panels and batteries and turbines, that that’s going to blunt a lot of the efficacy of turning over to these fuels?

HANNAH RITCHIE: I think what’s key to highlight here is that there are no perfect solutions to this. There are no perfect solutions to meeting our energy needs or the energy transition. And I think the tough reality is that if we’re looking for a perfect solution that needs no materials, that needs no land, that has zero impacts whatsoever, we’ll be waiting forever. And we’ll just stay on this course of fossil fuels. So what we’re looking for are solutions that are much, much, much better than fossil fuels. And the reality is that we have them.

Estimates for the amount of material requirements for mining is something like tens of millions of tons per year at an upper limit. Compare that to how much fossil fuels we’re currently extracting. That’s $15 billion tons every single year.

We’re talking about mining orders of magnitude lower amount of materials compared to fossil fuels. It’s vastly, vastly different. And these are very, very vastly different systems. With fossil fuels, you extract them, you burn them. You extract them, you burn them. You get nothing back in return.

What’s going to happen with the energy transition is that we’re going to need this massive ramp up period where we’re building stuff. Right? So we are extracting a lot of materials out of the Earth. But you can reuse that stuff at the end of its life. And I think we will also see massive leaps in terms of recycling or refurbishing these materials back into the system later.

So we will have this big ramp up period, but we’ll move to a much more circular and sustainable system, which is vastly different from a fossil fuel system where it’s just extract, extract, extract.

EZRA KLEIN: To hold on that point about recycling for a minute — if you have a car that burns gasoline, you burn every tank of gasoline until you’re done with the car. And there’s no gasoline left at the end of that. If you have an electric vehicle, when you want to trade up for a different model or your car has reached the end of its useful life, that battery still has lithium and other things in it that can be reused.

Right now, people reuse the minerals in electric vehicle batteries. And so, at the very least, there’s a possibility — I’m always a little bit skeptical of recycling because there are plenty of things that people think they can recycle that they cannot. But the things that are precious, you often can. And things like car batteries seem to be one of those even now.

HANNAH RITCHIE: Yeah, exactly. And I think, again, this comes back to underestimating how rapidly I think some of these technologies could shift, where it might not even be the case that the materials in your current electric car battery go into another electric car battery at the end of their life. They might be able to power more than one battery. And that’s because the material requirements for a battery in 15 years might be much lower than they are today just because we’ve had so much innovation and advancement in these technologies.

HANNAH RITCHIE: Yeah. So there are some studies that say if you take account of the mining, and the transport, and the full life cycle, actually sometimes the land footprint of coal is higher than it is for solar. But the fact that you get for some of these estimates is touch and go would suggest that the land footprint of solar is not massively bigger than it is for coal. The question of land use for these technologies is a perfectly valid one. But I think it’s important to highlight that these are choices.

And what I often think is a bit suspicious or people don’t take account of is that there are current land uses that we have that we don’t really question. But as soon as solar and wind come along, the guardrails go up and we shouldn’t build this stuff.

To give context, if you were to put solar panels in the U.S. on all of the land that’s currently used to produce biofuels, you could power the U.S. three times over. You would be able to easily decarbonize the U.S. and meet its energy requirements. That land use is a choice, and you can make a different choice.

EZRA KLEIN: I’ve never heard that about biofuel production in the U.S. So we’re talking things here like growing corn for ethanol?

EZRA KLEIN: And we are actually using as much of that as we would need for all solar combined?

HANNAH RITCHIE: Yeah. So if you put solar panels on that land, back of the envelope estimates suggest that you could meet the U.S.’s electricity demand around three times over.

EZRA KLEIN: So in some theoretical world, if we just paid off every farmer at above market prices for all the land being used for fairly low output ethanol from corn. We could solve a lot of these problems. I feel like that’s a version of this I’ve not really heard before.

HANNAH RITCHIE: I’m not saying this is a solution. I’m not saying we should put solar panels —

EZRA KLEIN: No. This is your policy. [LAUGHS]

HANNAH RITCHIE: No. I’m just making the point that we raise our eyebrows at the thought of how much land solar would need. But no one thinks about the land that’s currently being used for biofuels, and not particularly productive for U.S. gasoline and cars.

Tell me a bit about how you think of nuclear, which on the one hand is very clean, and on the other hand, I think people perceive as very dangerous, and on the third hand, if we had a third hand, really has a quality that wind and solar doesn’t, which is that it can kind of be anywhere and does not require very much land to generate a lot of electricity.

HANNAH RITCHIE: Yeah. So I think nuclear energy has a lot of merits, one of the primary ones being land use. If you want to conserve land and produce lots of energy, nuclear is ultimately your best option. It’s low carbon. It is safe. I give figures in the book looking at death rates from different forms of energy per unit of electricity production. And as we discussed earlier, fossil fuels are off the charts because — even if you take climate change out of the picture, even based on local air pollution they’re just vastly more dangerous than nuclear energy.

EZRA KLEIN: Well, can you zoom in on that for a minute? Because people have probably heard of two major disasters here, Chernobyl and Fukushima. Can you talk about the death rates of both?

HANNAH RITCHIE: Sure. So Fukushima in Japan in 2011, the death toll there — I mean, the direct death toll was zero. No one died in that nuclear disaster. Since then there has been — one of the workers has subsequently died of cancer. And then there are what they call excess mortality deaths from the stress of evacuation, the stress of the event. And they attribute that to several thousand, which is obviously a lot.

But as I said earlier, we have millions dying from fossil fuels, solely from air pollution every single year, even taking out the issue of climate change. So those numbers are just so vastly different that when you crunch the numbers per unit of electricity that we’ve produced from each of these sources, nuclear energy is just vastly safer than fossil fuels.

EZRA KLEIN: I want to talk about land here. Because we’ve been talking about that in terms of energy production, but I also want to talk about it in terms of use. Because how we use land is relevant to climate. It’s relevant to deforestation, which your book talks about, relevant to biodiversity loss, which your book talks about.

And I read this statistic every couple of months because of the kind of work I do, and every time I’m just stopped cold by it, which is at roughly percent of ice free land on Earth is used for agriculture. It’s a lot. [LAUGHS]

HANNAH RITCHIE: It is a lot.

EZRA KLEIN: Walk me through that.

HANNAH RITCHIE: Yeah, so if you take the world’s — what we call — well, we call it habitable land. So it’s basically taking away the ice and the kind of barren land that you literally couldn’t use for anything else, and other species couldn’t really use for anything else. Farming uses 50 percent of that. I mean, we produce around 5,000 kilocalories per person per day. Now, that’s around double what the average person in the world actually needs.

EZRA KLEIN: So how does that grazing land break down by animal?

HANNAH RITCHIE: So wild grazing land is basically just cattle, and sheep, and maybe some goats. But stuff like chicken, and pork, and fish, et cetera — I mean, fish where we actually feed them, not out in the ocean, they are not raised on grazing land. They’re raised on land where we grow the crops and then feed them to the animal.

EZRA KLEIN: So when you do that calculation sort of virtually everything — because goat and sheep are not major sources of human calories. They exist, but they’re not a huge part of the diet. All of the other meat aside from cattle is actually included in the crop raising calculation.

HANNAH RITCHIE: Yes, exactly. Yeah.

EZRA KLEIN: So functionally, we are using a huge portion of usable human land to raise cows.

HANNAH RITCHIE: Yeah. We’re using a huge amount of land to raise cows. I mean, sheep are not totally insignificant. Especially on more marginal lands, they are actually quite large land users in some countries. But, yes, it’s primarily cattle. And cattle ranching is also the leading driver of deforestation globally. So again, it’s not just that we’re using a lot of land for this. We’re actively cutting down forests and more land to raise more cattle.

HANNAH RITCHIE: Yeah. So if you look at the history of global deforestation, it increased very rapidly in the 20th century. But various estimates point towards a peak in global deforestation around the 1980s. We have targets of getting to zero deforestation by 2030, and we’re really not on target for that. So we still have large amounts of forest being lost, but less than we were cutting down in the 1980s.

What’s been really key there is a shift in where deforestation is happening. In the U.K., we cut down our forests centuries ago. And we then had all of this agricultural land to use. In temperate countries, deforestation has definitely peaked. And now many forests are coming back. We’re regrowing forests on these old lands. The center of deforestation today is in the tropics. So nearly all of our global deforestation is tropical deforestation today.

EZRA KLEIN: Beyond agriculture, to the extent there is a beyond agriculture, what are the drivers of deforestation? If we wanted to take what is happening in the tropics seriously, if we wanted to blunt it, what is the equivalent of shifting the energy system to renewables?

HANNAH RITCHIE: I mean, when it comes to deforestation, it’s nearly all about farming. Cattle ranching is the biggest driver by far, followed by oil crop production, so soy and palm oil. And then there are a couple of other major drivers or crops. Rubber, for example, is a growing one. There’s some deforestation for cereal production. In some regions, the primary way to increase food production in the absence of increases in crop yields is to just cut down forest and use more land.

EZRA KLEIN: And what’s the role of this in climate?

HANNAH RITCHIE: So I think people underestimate the contribution of food to climate change. So if you look at the breakdown of emissions, around a quarter to a third of emissions come from food systems. I think if you take emissions from livestock alone, it’s somewhere in the region between 14 percent to 18 percent of greenhouse gas emissions. Without any change in this trajectory in food that we’re on, emissions from food alone would take us past 1.5 degrees.

EZRA KLEIN: And tell me about the role here in biodiversity. I think people know that there is a huge, genuinely historic level of species extinction happening right now. And I think in their minds — in many of our minds — people assume it’s probably climate, right, or making the world hot and messing with weather. And that’s destroying species. And in some cases, that’s true. But talk me through the research on the relationship between that and how big of a driver functioning our food system is.

HANNAH RITCHIE: I think the first thing that jumps out when you look at the research is how little we know about the world’s biodiversity. Quantifying carbon emissions is easy. Quantifying what’s happening to the world’s biodiversity is really, really difficult. And the researchers in this area do amazing work. But biodiversity is just so vast that they’ve hardly even touched the sides.

But what’s clear from the data that emerges is that most of the trends are downward, and downward very steeply. I always get this question, are we in the middle of the sixth mass extinction?

And a couple of ways to look at this is the world has been through five big mass extinctions previously. And the definition of a mass extinction is losing around 75 percent of the world’s species in a geologically short period of time. And by short here, we mean within 2 million years. Not short to us, but on geological periods a relatively short period of time.

And I think what’s quite alarming is that, when you look at this data, the rates by which species are going extinct today are higher than any of the five previous mass extinctions. The key difference there is that in the previous mass extinctions there were these sustained very high rates for very, very long periods of time.

My optimism on this is that even though extinction rates are very, very high they can be stopped. And they can be stopped because we are literally the handbrake. We are the ones driving this, and we can be the ones to stop this or certainly slow it down vastly.

Climate change is one driver, and I think will be a 

 growing driver of biodiversity laws in the future. But it’s not top of the list. The biggest drivers of biodiversity loss are basically what we call direct exploitation or food production. So that’s stuff like overfishing. That’s stuff like deforestation or logging for wood. That is driving deforestation for food production. That’s conflicts with livestock.

So it’s really food production that is the biggest driver of biodiversity loss by far. And again, climate change, I think, will grow in the future. But it’s currently not the biggest threat.

The reason I think that the climate movement doesn’t emphasize the role of beef and the role of dairy is because it is just insanely, unfathomably lethally unpopular to do so. There’s a reason the right is always accusing the left of wanting to ban hamburgers. And the left does not want to ban hamburgers. And, in fact, most people I know who worry about climate eat hamburgers and eat steak and all the rest of it.

But at the same time, of the things you could do that would one, have a pretty significant effect on emissions, on deforestation, on biodiversity, and I think not totally incidentally from my perspective, animal cruelty. So there’s something here where, this is really, really, really, really, really big linked across a bunch of our problems, and yet totally politically untouchable. I’m just going to put a question mark here and just ask how you think about this.

HANNAH RITCHIE: So on this I’m just way more optimistic about the energy transition than I am about the food transition. Overall, people might have some biases towards what energy source they like. Ultimately, they just want cheap energy coming out of the plug. And if you can give them that, they’re not that bothered.

That’s not the same for food. Right? People are actively making decisions about what they eat three or four times a day, and they really care about what they eat. And they will push back if you try to tell them what to eat.

So I don’t have a good answer to how we actually achieve this, just to say that I think this will be much more challenging than, for example, the energy transition.

EZRA KLEIN: It’s so interesting, though. Because it’s so technologically simple compared to the energy transition. On the energy transition, we’re having to figure out how to get all of these electrons we generate in other ways and replace them with these space age — we’re going to do what they do in stars and create nuclear fusion. Right? We’re going to harness the power of the sun. We’re going to use a nuclear reaction.

And here it’s like, you could eat something different. You could shop in just literally any other part of the grocery store. But it gets at this truth, I think, across this whole transition, which is that the problems are not nearly as technological as they are political and cultural.

And maybe to add one other complication here from the animal suffering side, I think a lot of people in the animal suffering and animal rights movement worry about this. Because I’ve known many people who see this data and decide to give up red meat. They decide to give up beef. But from the animal suffering perspective, that’s very, very, very bad if you substitute with chicken or fish or other smaller animals. Cows are known for living better lives even in industrial agriculture than, say, chickens. And a family can eat a chicken and a night. It takes them a year to eat a cow. So in terms of the total numbers of animals that you are killing or raising in very difficult conditions, cows mean fewer of them.

HANNAH RITCHIE: No. And I think the trade off between animal welfare and environmental impact is a really underrated one. I wrote about this previously, an article in Wired, where I think the title was something like “Should We Kill Trillions of Animals to Save the Planet” or something. And it was getting at the heart of this, where the amount of chickens you would need to kill to produce the same amount of beef is just orders of magnitude lower despite the fact that it would have a lower carbon footprint and a lower environmental impact. And that’s just a naughty and hard to grapple with tension between these two outcomes.

I actually wish I had said more about this in the book. I think my dietary habits have actually changed in the last few years because of this tension, where I had very much motivations that were just about environment and climate. So I cut out red meat. I mostly cut out dairy. And I’d sometimes eat some chicken and fish, because they have a relatively low carbon footprint compared to other meats.

But in the end, I just couldn’t handle the tension with the Animal Welfare question, which is one, the number of animals that you have to kill to produce the same amount of beef. But also, to me, just the welfare standards of many of these animals is worse. Right? For me, just a chicken packed into a cage or a barn just seems to have a lower standard of living than a cow in a field, even if it has a much, much lower environmental impact.

So I couldn’t handle that trade-off and that dilemma, so I opted out and went completely vegan. But it is really hard to communicate this to people. And my approach to this is to give people good information, and then hope that they then make the right decision for them. But I’m not going to pretend that this is going to move very quickly, because I don’t think it will.

HANNAH RITCHIE: So if the world shifted to a fully plant-based diet, which we’ve got to be clear we’re very, very far away from. But if we did that, we could reduce global agricultural use by 75 percent. So we basically shrink global agricultural land to a quarter of what it is today. And you could feasibly feed everyone on that land.

EZRA KLEIN: I always just find this astonishing. I think people imagine human land use and what they think of as humans. We think of where we live. We think of where we build buildings. But actually, just a huge amount of that land is just raising cows for humans. That’s what we’re talking about here actually in terms of the human land footprint — raising cows for us to eat, or drink their milk, or consume their cheese.

HANNAH RITCHIE: Yeah. I think I you’re really, really set on the cows. I think I’d just say in general food production, but you’re right that by far the biggest land user there is cows. But you’re right. The land footprint of humans is really not about where we live or where we build stuff. Urban land area is about 1 percent of global land, maybe a few percent if you add in stuff like roads and other infrastructure. But you’re talking about a few percent for where we live and nearly half of habitable land for the food that we eat. Ultimately, the land footprint of humans is very much what we eat.

EZRA KLEIN: One thing you talk about at the end of your book is the way in which being a good environmentalist by the numbers sometimes makes you feel like you’re being a bad environmentalist in your actions. And you talk about this as the natural fallacy, that there is this tendency to believe that things that feel natural — cooking on a word burning fireplace or getting all your food from within 10 miles — often do not actually align with what the data tells us is environmentally sustainable. Do you want to talk through that feeling bit and how you’ve resolved it in your own life?

So if you take the example of food, what seems good to us or natural to us is a nice picture of a cow in a grass field, and especially if it’s from a local farm. Right? That seems like just the lowest way possible to produce that food. Right? You’re not growing crops on croplands. You’re not transporting the food very far.

And compare that to, for example, a meat substitute that’s grown in a lab or produced in a factory, where you’re using loads of energy for the processing. It’s coming in packaging. You’re putting in lots of ingredients and chemicals, as people would say. That seems really bad, and the beef in a field — or a cow in a field seems really, really good.

And, of course, when you break down the data, the emissions from the meat substitute burger are just vastly, vastly lower than the beef. So many of our gut instincts on this are often very, very off. And as I say in the book, this often makes you feel quite bad as an environmentalist. And you will get pushback. You’ll get pushback on, for example, the local food story, where people just assume that the best way to reduce the carbon footprint of your diet is to buy locally, even if that is beef.

And if you’re buying a product that’s being shipped in from the other side of the world, they assume that has a very high carbon footprint. And therefore, that’s a very bad thing environmentally to do. When you break down the emissions of those two things, the vegetarian product that’s shipped in probably has a vastly lower footprint.

EZRA KLEIN: So I’ve done most of the things that would reduce my personal carbon footprint. I live in a building in a dense urban area. I’m a vegan, or mostly vegan. I slip up here and there. But I travel by air. And either I don’t go see my family in California or I am emitting that carbon. My view on everything we’re talking about with cattle and with sheep, and with goats — and so I do think there is this question between the places where the only answer is abstention, which is a very, very hard form of politics, the places where the answer is substitution, which is a much easier form of politics, particularly when the substitutes are good — moving to electric vehicles is much more possible now because the electric vehicles are very good — and the issue where we believe we might be able to invent a substitute but we haven’t done it yet.

My view on the issues of meat is that until we figure out the whole cell-based meat thing people are trying to work through, which is going slowly — it’s not like we’re going to have affordable meat replacements tomorrow where people can eat the meat they want to eat without the animals being nearly so involved — we’re not going to solve that.

HANNAH RITCHIE: Yeah. On the beef question, I’m with you. I’m very pessimistic that most people make that switch to existing products that we have. And I think my pessimism around that behavioral change pushes me towards a technological fix, where we can literally produce like for like substitution for beef.

And I think ultimately, in the end we will be able to do that, just not in a very, very short time scale. My concern with some of this is that we have some fantastic technologies to address some part of our emissions pie, so primarily electricity and road transport. We now have very, very good solutions for those. We have them. We need to build them really, really quickly. Right? We just need to build, build, build, build, build.

And in some of those, I’m actually quite optimistic that in the next decade some of these solutions come online. But the key thing is not to get discouraged that we don’t have all of the solutions now and let that hold us back from deploying the technologies that we have and we urgently need to roll out.

EZRA KLEIN: This is, to me, something that has actually changed. And it is required a change in our politics. It is happening right now, but is very messy, which is for a lot of the history of the environmental movement, we didn’t have good substitutes. And to get some of these problems to a point where they were being ameliorated, we had to get people to stop doing things or we had to add new technologies to things we were already doing, like the scrubbers for sulfur dioxide.

And now we have this capacity to substitute with solar panels and wind and electric vehicles and heat pumps. And it requires a huge amount of construction, transmission lines. And so you have this movement and this politics that for a lot of its life was about trying to get human beings to do fewer destructive things and now needs them, very rapidly, to do far more constructive things.

And that’s actually new. That actually is a change from the dominant answer we had to environmental problems in the ’70s. And the fact that it’s messy and difficult is a little bit to be expected. I mean moving from an environmentalism of stopping things to environmentalism of building things is almost reversing the polarity of an entire political sentiment.

If we’re relying on that to get out of this climate crisis, I would have very little optimism about our ability to do so. People always frame me as a kind of techno optimist. But I think I lean that way because I’m just more optimistic about the substitution effect rather than a stop doing this effect.

But I think you’re right that it is a massive change. A point I make regularly now is that many of the big solutions we need, we have. And we have solar, wind, electric cars, et cetera. They’re good solutions. They’re now really, really cheap, and it’s just about building them.

And often they get the pushback of well, yeah, but we’ve had the solutions for decades now and we just haven’t done anything. To me, that’s just really, really not true. We haven’t had cheap replacements for fossil fuels for decades. This is really a change in the last five years. It’s only in the last five years that low carbon technologies have now become competitive or undercutting the cost of fossil fuels. This transition was just not feasible 20 years ago.

Of course, you can argue that countries should have been investing more in these technologies 20 to 30 years ago so we would get to the position faster. And I agree with that. But to me, it’s just not true that we’ve had these solutions just sitting there ready to build for decades and decades and we just haven’t done anything. We’re in just a fundamentally different position going forward.

And so in my writing about climate change 10 years ago, I was extremely pessimistic. And it was only the shatteringly fast drop in solar wind and battery cost that has made me relatively more optimistic. But that’s only to say that if you begin from the perspective — and I do begin from it, or at least I’ve concluded it — that there isn’t a politics here that is going to work that is a politics of sharp and near-term sacrifice.

The politics here somehow has to align with people’s desire for a better life, a more prosperous life than the one they currently lead. And as that becomes more technologically possible, the politics become more possible in lockstep. And to the extent that it’s technologically not possible, as in the case of, say, meat or as in the case currently of cement, the politics are not possible. We’re not going to get people to stop eating beef. We’re not going to get people to stop using cement.

So I don’t really want to have all my chips in on inventing solution after solution to the problems that human beings create. But I don’t really think there’s a choice.

HANNAH RITCHIE: No. I think I’ve ended up in a similar position. It was often framed as this kind of iron law, where if you put up climate mitigation against either energy security or energy cost, energy security and energy cost will win every single time. And that’s just the harsh reality of this. And therefore, if we want to make progress on climate change, then what’s really key is that we line up this long-term incentive of climate change with short-term incentives. And short-term incentives are primarily about cost and quality of living.

EZRA KLEIN: I think that’s a good place to end. So then, always our final question, what are three books you would recommend to the audience?

HANNAH RITCHIE: So my first book is called “Factfulness,” and it’s by Hans Rosling. And anyone that knows my work or knows Our Own Data will know that we were massive fans of Hans Rosling. And he was a big inspiration to me. And he was really the first person that got me into looking at the world through data, and really zooming out to understand what was going on.

And his book in “Factfulness” looks at the long history of many measures of human well-being and global change, but more importantly kind of gives 10 key rules or pitfalls that guide you into how to understand the world, how to understand data, how to understand the information ecosystem , and how that shapes your thinking in the world. So it had a profound impact on me, and I hope it does on you as well.

My second pick is a book called “Possible” by Chris Goodall. Now, he is a U.K. energy analyst. And what he does in this book is looks at the solutions that we need in so-called “hard to abate” sectors on climate. And I think when people hear “hard to abate” they think impossible to abate. And really, the key point of Chris’s book is that it will be hard but it’s possible.

So, for me, it just gives a very, very clear eyed vision of this set of sectors that we need to tackle, and what our options in this space might be. It’s not prescriptive. It doesn’t say we have to do this, or we have to do this. It just lays out very, very clearly these are the options that we have. And, for me, it made me more optimistic that we will get there.

And then the final book for me is called “Range,” and it’s by David Epstein. And it’s really a book looking at this contrast between specialists and generalists. And the key point of the book is that, really, the world needs more generalists. I think we have a lot of specialists, and we absolutely need specialists. We won’t get anywhere on any of these engineering problems or climate problems without specialists.

But we also need generalists that can somehow sit in the middle, pull these different pieces of complex problems together, sit in the middle of different disciplines — so whether that’s research and communication, or research and policy — and be able to incorporate a wide range of disciplines and inputs, and then somehow drive that to change in the world. So I think my takeaway from that is that we need a bit of a better ratio of specialists in the world to generalists.

EZRA KLEIN: I can see why you like that book, given that I think that’s something you do very well and you do very well in this book. And it’s the connections you’re able to draw here between different domains of environmental disaster that ends up being so powerful. Hannah Ritchie, thank you very much.