When Christiana Figueres took the reins of the United Nations’ international climate negotiations in 2010, hopes were not high that the world would come together to forge an agreement to tackle global warming—especially after talks had fallen apart in Copenhagen the previous year. In fact, when she was asked at a press conference if she thought such a global agreement would ever be possible, she replied, “Not in my lifetime.”

But when she walked out of that press conference, Figueres says, she realized she needed to shift her thinking and messaging to one of possibility—what she and Tom Rivett-Carnac, her chief strategist from 2013 to 2016, call “stubborn optimism” in a new book aimed at inspiring continued climate action. They argue that believing real change is possible and pushing for that change were crucial to drafting the landmark Paris climate agreement in 2015. And Figueres and Rivett-Carnac say this approach will be equally important to the monumental task of reaching net-zero emissions (where carbon dioxide is no longer building up in the atmosphere) by midcentury to limit the earth’s temperature rise. The Paris Agreement’s stated goal is to keep warming to less than two degrees Celsius above preindustrial temperatures but to aim for an even lower 1.5 degrees C.

The book, The Future We Choose: Surviving the Climate Crisis (Knopf, 2020), aims to expand their message from the wonky world of international climate negotiation to the broader public. It lays out imaginary futures in which the globe does and does not bring emissions under control and the strategies that can be employed to choose the less destructive path. Figueres and Rivett-Carnac sat down at Scientific American’s offices to discuss the book and what drives their own optimism.

[An edited transcript of the interview follows.]

What prompted you to write this book and to do so now?

RIVETT-CARNAC: The specialness of this year—2020 is the beginning of the decade in which we are going to have more of an impact on the future of humanity than in any decade in history. And that sounds like an exaggeration, but it’s not. By 2030 we need to have reduced our emissions by 50 percent, minimum, if we’re to have any chance of keeping climate change to 1.5 degrees C. If we start now, that’s more than a 7 percent reduction every year. That is a mobilization at a scale that’s barely imaginable. Now it is achievable, and science tells us that it’s achievable. But we’ve reached the point at which we’re going to discover if we’re serious about dealing with this. So this book is about communicating what’s at stake.

We have allowed ourselves to feel powerless in the face of this challenge. But the reality is that we have more power than we can possibly imagine, because of the impact we can have. And so we hope that people reading this book will, at the end of that, feel the sense of importance of this moment—but also a sense of empowerment that they can be part of this great generational endeavor that will improve the future for all generations to come.

When you talk about the need for climate action, how do you find a balance between individual responsibility versus the need for larger systemic change?

FIGUERES: Well, we actually don’t think that this is systemic versus the individual. This is an “and also” [situation]. Now it’s about everyone everywhere—at all points in time.

Also, we tend to forget that both governments and corporations actually respond to their reading of what the individual is demanding. The clearest single [example of] that recently is what has happened with plastic straws. We had one or two very, very moving photographs of a straw that had pierced the nose of a sea turtle, and that went viral. And individuals then decided, “I’m not going to use a plastic straw anymore.” I have yet to see a government that put in a law that said, “Thou shalt not use a plastic straw.” They interpreted the human reaction—that is, the collection of all of us who decided no more plastic straws. You don’t see a single company now making major investments into plastic straws. You see many, sometimes even new, companies creating jobs and [making] investments into creating and producing straws—which we still need—out of other products. The point is that was a sea change that occurred because of individual decisions taken to change individual behavior. We tend to underestimate the power of the individual.

A key message of your book is about maintaining optimism that we can make the choices we need to make to limit climate change. How do you personally maintain that optimism? And are there any recent actions or developments that have buoyed it?

RIVETT-CARNAC: People tend to think of optimism as a sort of generic sense of “things are going to be great,” or a sunny outlook, which is very different from what we mean in the book. In the book, we coined a phrase called “stubborn optimism.” And the way we define that is less a sort of attitude of mind and more a strategy to change the world. So what we say is that in the face of this unbelievable challenge, we have a responsibility to dig in and say, “We will not allow this to happen on our watch.” Now we see that as a form of optimism, a belief that the world can be changed.

Alongside that, there are loads of good things happening—if you care to look—on climate change. Just one example is that right now, countries, investors, cities, businesses—if you add them all up, it’s about half of the world’s GDP that has already [been] committed to [an emissions reduction] target that is sufficient to keep us to 1.5 degrees C. We can take huge heart from that. And of course, it’s easy to forget that it’s only been 15 months since [teenage climate activist] Greta [Thunberg] gave her speech at the [2018 United Nations climate change conference] and how quickly that’s changed the world. So if you care to look, there are really good things happening. But that sense of optimism is how we’re going to do it.

Given that there is already a lot of inequality baked into our existing economy and energy systems, how do we make the changes that need to be made in an equitable way?

RIVETT-CARNAC: I think that climate change is fundamentally unfair. And I think that’s one of the things that really grabs people, actually—that sense of the injustice of this. And it’s unfair in multiple ways. It’s unfair generationally, because it’s the young people who are going to bear the brunt of this—and they’re very aware of that now. And there’s real anger on the part of young people. It’s unfair geographically, in the sense that those countries that have done the least to cause it are, in many cases, tragically going to be the countries that are going to be most affected. It’s unfair economically, in the sense that, actually, it’s people with less means—who’ve done the least [to contribute to the problem—who] are looking like they might well be disproportionately affected as well. Former secretary of state John Kerry, who was on our podcast Outrage and Optimism, said that [climate change] is a threat multiplier—because it applies to everything. It applies to national security threats. It also applies to these injustices. It’s an injustice multiplier as well.

The flip of that is that there are enormous opportunities to actually create a better world with better jobs. In making this transition, it is entirely within our capability to provide training and support to people, to help them embrace this new economy. But that requires deep public policy thinking that happens in multiple countries around the world—around what is the best use of public money to help people embrace this transition. I think we’re generally not doing a great job, from a public policy perspective, of really getting a handle on what that world is going to look like. Because, of course, there are multiple other forces at play. A nice example is plant-based protein: That could be great because of the enormous amount of land that goes into producing soy to then feed cattle, et cetera. At the same time, it could lead to massive agricultural unemployment if not done well, which could lead to political extreme swings, et cetera. There are ideas out there like universal basic income and other things that are kind of being kicked around—or the cap-and-dividend idea, where you cap emissions, then you distribute the proceeds across the population. That type of thinking needs to go further and faster.

One strategy for lowering emissions that has gotten a lot of attention recently is planting trees. President Donald Trump has even touted this idea. How do you try to communicate that there is no magic bullet to solving this problem and that we need multiple solutions?

FIGUERES: Think about the carbon budget—the absorption capacity of the atmosphere—as a huge bathtub. And for the past 100 years, we have opened the faucet. And especially in the past 50—actually, the past 10 to 20—years, we have opened that faucet to its absolute maximum. And we have been filling that bathtub up very, very quickly. Now we’re at the point at which we’re almost at the brim of that bathtub. And if we go over the brim, that water will spill and make it completely impossible for us to control the effects of climate change.

Had we started this 20 or 30 years ago, we could actually rely on closing that faucet gradually. We can’t do that anymore, because we’re almost at the brink. So, number one, we have to close the faucet drastically, halving emissions by 2030. But, also, we have to use the drain at the bottom of the bathtub. Now there are many ways to do that, right? You can invest in carbon capture and storage. You can do direct air capture, which is now being developed. The problem is that industrial carbon capture and storage is currently still an incipient technology and very, very expensive. And direct air capture is an even more incipient technology. The one technology that actually captures carbon from the air and puts it back in the soil—that is tried-and-true, that is a technology that we have had for thousands of years, that has no safety risks and that we know has many, many other beneficial effects—is growing trees or growing any other kind of biomass. It’s taking care of nature and actually replenishing and regenerating nature’s capacity to deal with the carbon in the air. So what we have to understand is that one thing cannot replace the other. We have to both close the faucet and drain the bathtub. We actually have to do both with environmental integrity, not as a greenwash.

RIVETT-CARNAC: We would say that any corporation or national leader that claims that planting trees means we don’t have to do the hard work of decarbonization is trying to divert our attention from the real issue. There are some gas companies that do that. Certainly, President Trump is doing that. That absolutely should be called out because that has the potential to slow us down.