Top climate scientists have long warned that swiftly curbing fossil fuel production will be necessary to avert climate catastrophe. Yet international climate treaties have failed to include such commitments. Despite pressure from vulnerable nations and activists, in the agreement signed at international climate talks last year, world leaders failed to commit to a fossil fuel “phase-out”, instead calling for a “transition away” from coal, oil and gas. Its a longstanding problem: the 2015 Paris agreement does not even mention that fossil fuels are responsible for global heating.

That paradox led climate-vulnerable nations and civil society groups to launch the Fossil Fuel Non-Proliferation Treaty Initiative. First dreamed up following the Paris climate talks and officially launched in 2019, the proposed treaty would include concrete plans for the phase-out of fossil fuels, complementing the Paris agreement. It has been endorsed by 13 countries including Colombia and vulnerable island nations such as Vanuatu, as well as hundreds of elected officials, 118 cities and municipalities, and thousands of organizations. Inspired in part by the 1968 nuclear non-proliferation treaty, which aimed to prevent the spread of nuclear weapons, the initiative calls on nations to agree to halt the expansion of coal, oil and gas.

On Monday, the treaty initiative announced its new president: the longtime South African activist Kumi Naidoo, the former executive director of Greenpeace International and former secretary general of Amnesty International.

The Guardian spoke with Naidoo about his vision for the fossil fuel non-proliferation treaty and why he is optimistic that it will prevail. This conversation has been edited and condensed for clarity.

Congratulations on your new role. How are you feeling stepping into it?

It’s a complicated question. Since stepping down from Amnesty in 2019, I’ve been focused on why activism is not winning enough. I realized a major challenge is communication. State-controlled, corporate-controlled media are generally resistant to giving coverage to ideas that go against the status quo. But also, we climate activists tend to focus on the science, the policy – tend to focus on the mind and ignore the heart.

In 2019, the Icelandic artist Olafur Eliasson invited me to a funeral for an iceberg in Iceland. The funeral was probably more effective than about 95% of actions because it wasn’t about science or degrees of warming, it was about loss. I began to realize that we needed to harness the power of arts and culture to push the climate agenda forward. Later, I had an opportunity to be a fellow in Berlin with the Bosch Foundation, which is where Olafur is based, and he and I did joint interviews speaking to both the cultural world and the activism world.

While I was in Berlin, I had a personal tragedy that pushed me even further in this direction. My son was a very popular musician, a rapper, a hip hop artist. He committed suicide. In the last face-to-face conversation with his mum and I six weeks before, he joked with us and said you guys are really not good at your jobs, because the things you have been working on since you were teenagers, human rights, democracy, gender equity, sustainability and so on are going in the wrong direction. You’ll need to learn to really connect with people.

When I asked him what we were doing wrong, he said, you’ll know how to talk to yourselves, not people living in poverty who don’t have time to read reports and so on. You should not focus only on the brain and ignore the heart, body and soul.

His mom and I started the Riky Rick Foundation for the Promotion of Artivism to begin bringing the world of arts and culture and activism together. We just held our inaugural artivism conference in South Africa. One of the most powerful endorsers of the fossil fuel treaty is This Is Our Home, a collective of artists. They were the star performers at the artivism conference.

Wow. How did you then come to this new role with the treaty?

Tzeporah Berman [the Canadian activist], the founder of the treaty, told me that the 2,000-plus endorsers of the fossil fuel treaty had also been saying there needed to be more use of art and culture. She reached out to me about whether we could bring the fossil fuel treaty and artivism project together. That was the conversation that started this.

The endorsers were asking for more arts and culture from the bottom up. I was very impressed with the treaty’s understanding that you have to have a people-driven process. So when Tzeporah had the idea for me to become president, I did it. It’s absolutely the right place for me to be. I feel that the treaty is the most optimistic climate intervention that we have going on right now.

We’re speaking less than two months before Cop29 begins in Azerbaijan. What will efforts to boost the treaty look like at those negotiations?

We’ll have to convince especially the most vulnerable countries in the world that there is no contradiction between making sure that we get the positive things from the Paris [agreement] adhered to, and also get something that is stronger and more enforceable than the agreements that we get out of Cop negotiations. Right now, we think that we are on the brink of being able to make that breakthrough. So our focus will be on the most vulnerable countries, small island states, the least developed countries.

We see the climate negotiations as deeply imperfect in terms of who has a voice and who is in the room. We know that thousands of fossil fuel lobbyists are in the room. At the Glasgow negotiations in 2022, there were more people from fossil fuel companies than there were delegates from any country. But the negotiations are still the best game in town in terms of getting to consensus on solutions. And so we need to make sure there are sufficient levels of pressure on governments while we’re there.

The good news is, the level of climate consciousness is higher than ever. A lot of that is thanks to activism. But activists must also ask how we can improve. And some of those new approaches, like using arts and culture and using different communication approaches, are some of the things that we do.

We’re speaking as Greenpeace USA faces a serious legal battle, with the pipeline company Energy Transfer seeking $300m in damages from the non-profit over accusations that Greenpeace entities incited protests against the Dakota Access pipeline in 2016 at Standing Rock, funded attempts to damage the pipeline, and spread misinformation about the project. Greenpeace USA says the suit would wipe out their organization and constitutes an “existential threat”. Could you talk about the challenges facing Greenpeace and other climate advocacy groups?

The Global Witness project tracking the environmental activists who are killed is important to remember. Ten years ago, they found two activists were killed a week. That number has nearly doubled. So we are operating in a very difficult situation. Civicus: World Alliance for Citizen Participation has also been tracking how in the last two decades, since the so-called Patriot Act passed in the US, there has been a systematic attack on freedom of assembly and expression. Elsewhere, Amnesty and Greenpeace and others have also come under attack, like under the Modi government in India.

To the specific issue of what’s happening to Greenpeace USA, essentially, this is a Slapp lawsuit, or strategic litigation against public participation. They are hoping to get a judgment not because they need the $300m, but because they want to make sure that resistance to fossil fuel infrastructure is opposed. But I have seen similar cases where creative activism can turn things on its head. And here, I would say that the company in question might actually regret bringing this case, because I think if Greenpeace USA can go to the people in the US to explain what’s happening, this will be one of the most visible campaigns they could launch and actually raise consciousness and support. I hope that the company will withdraw the case, but if they don’t, they need to understand they will hurt their reputation beyond anything that they’ve already experienced.

Is the treaty taking steps to ensure it can withstand any potential criticism or attacks from the fossil fuel industry?

I think right now the industry is just monitoring and observing. They’re not saying much about it, but I think they will start [to be] more anxious … when we go from 16 countries that are signing up … to about 25 countries. Once we get to 25 they’ll start taking this more seriously.

I don’t think they will engage us publicly because they’ve got no basis to do that. Even Saudi Arabia accepts the science of climate change today even if their actions are inconsistent. And every fossil fuel company acknowledges that their product is driving the climate crisis.

We won the debate at that one level: the companies all say, yes, we accept the science. Now it’s about the urgency, about how quickly we phase out fossil fuels.

But it’s important to remember that the fossil fuel industry has been aware of the climate crisis for decades. So more than anyone, they stand accused of betraying our children’s future. So they already face this serious repetitional problem. I don’t think they’re going to stop this treaty from coming into place.

Global consumption of fossil fuels reached record levels this year. Global leaders plan to produce more than double the amount of fossil fuels in 2030 than what is consistent with capping global temperature rise at 1.5C. Can the non-proliferation treaty’s efforts prevail?

In the moment of history that we find ourselves in, pessimism is a luxury we simply can’t afford. Pessimism that justifiably emerges from our observations, our lived experience, and our analysis of the situation can and must and should be overcome by the optimism of our thought, our action, our efforts, our courage and our sense of humanity.

Now, I don’t want to suggest to you that we are in a good place. But I’m optimistic because we don’t have another choice. We don’t have another choice other than to push our leaders as hard as we can. And I believe, both believe the scale of the crisis is what will help us deliver change, combined with the growing sense of urgency, the sense of courage that people are bringing to the fight to save our children’s future, and also young people themselves.

Part of what we will be trying to do with the treaty is to make it as accessible as possible. Don’t focus simply on the legal instrument, important as it is, but make sure that people are making connections, that the treaty is about our children’s future, is about our water quality, air quality, it’s about our survival on this planet.

I’m not saying this is a walk in the park. Far from it. But we are at a point where sanity needs to prevail, and the fossil fuel non-proliferation treaty offers us a road to sanity.