When knowledge is no longer enough, then what?

Interview with director Florian Heinzen-Ziob about THE WEIGHT OF THE WORLD, by Maya Reichert

Three scientists, three life paths, one shared dilemma: they know just how serious the climate crisis is, yet at the same time they see how little impact this knowledge has. For glaciologist Maria, chemistry professor Sebastian and molecular biologist Nana, this calls into question not only their research but also their very role as scientists. Faced with this dilemma, they take action, leave the laboratory and seek new paths between education, public engagement and protest.

In the documentary film THE WEIGHT OF THE WORLD, Florian Heinzen-Ziob follows this transition from awareness to action. The film promises not only an insight into scientific work, but also into a period of upheaval, both internal and external: what happens when the people closest to the crisis can no longer remain silent? The protagonists and the director will be guests at DOK.fest Munich, where they will answer our questions about the film.

When did it dawn on you that this film had to be about scientists who are no longer merely observers?

As a documentary filmmaker, I have long wondered how I could contribute to tackling the climate crisis. Then, in 2022, I read an article about marine biologists who, following an extreme weather event on Canada’s Pacific coast that claimed the lives of billions of marine creatures, were examining the dead bodies on the beach. I wondered: how are these scientists faring, who set out to explore the wonders of nature and are now chroniclers of a dying world?
Shortly afterwards, the Ahr Valley disaster struck. I sat with my mother in the garden of my grandparents’ flooded house, where I had often played as a child, and we tried to rescue photos and documents from the mud and water. Many of the family heirlooms were lost forever in the process. It then dawned on me that I had to make a film about climate change, but not far away in Canada, but here in Germany, right at my doorstep.

Your protagonists work with highly complex data, ranging from ice cores to molecular processes. How can such abstract scientific findings be translated into film without oversimplifying them?

In fact, this was a major challenge I faced whilst working on THE WEIGHT OF THE WORLD. Scientific work often takes place in front of a computer screen, which is difficult to convey on film, and scientific language can quickly become so complex that it excludes the majority of the public.
That is why my approach was to explain individual aspects of scientific work in detail. What is an ice core and what role does it play in collecting climate data? How can polymers help produce drinking water? At the same time, however, I also wanted to show scientific work in general, how the facts of the climate crisis are painstakingly established through meticulous processes.

At what point do your protagonists feel that scientific responsibility can no longer be confined to the laboratory?

I believe that Maria, Nana and Sebastian have all realised for themselves that it is not enough to simply hand over their climate change research data to politicians, the media or other stakeholders and trust that they will do the right thing with it. They had to accept that their responsibility does not end with the handover of the data. Maria says in the film: “My science isn’t some nice game I’m playing; it has concrete consequences for millions of people.” And Nana says that if those who know best what the current situation is like do not reflect this in their actions, how can we expect the rest of the population to do so?

The film repeatedly addresses the question: why do scientific findings fail to gain traction? What did you learn during your research and filming about why this communication falls short? What forms of communication do you believe are still effective today?

There are complex reasons why scientific findings on climate change are failing to gain traction. There are very powerful players who are deliberately obstructing or casting doubt on the debate. There are psychological and neurological reasons why we humans find it difficult to grasp this existential crisis. It calls into question our economic system and also our self-image of the Western Enlightenment, individual freedom and humanity’s detachment from nature. And it raises questions of justice, temporally between generations, and spatially between the Global North and South.

Whilst filming, I felt that Maria, Nana and Sebastian were at their most compelling whenever they communicated authentically and honestly. When they were talking about themselves. Like Sebastian, who talks about the loss of his homeland, sleepless nights and chronic exhaustion. When they communicate not in a lecturing or evangelical way, but as equals, as people searching and struggling. This is exactly what I tried to capture in the film.

Your film revolves heavily around the idea that knowledge can be not only insight but also a burden. How did you address this feeling of being ‘overwhelmed’ in your film?

The particular challenge with this film is that, unlike in my previous films, I am no longer just an observer, but am simultaneously someone affected by the issue and part of the problem. So I often found myself sitting down to dinner with my cameraman after a long day’s filming, and we would talk about what we’d filmed that day meant for us and, above all, for our children.
I feel that campaigning for the climate crisis always involves a sense of isolation. Even though people always say that what you should do as an individual to combat the climate crisis helps you become part of a community. An alienation from colleagues, friends, and sometimes even your own family, who can’t – or won’t – listen any more, and for whom you become a nuisance.

Thus, in my film, alongside the many moments of action, exploration, discussion and struggle, there are repeated moments of calm and solitude. Moments of solitude. Nature and the surroundings in which the protagonists live and feel at home play an important role here. These are quintessentially German places such as the Harz Mountains, the Alps and the North Sea coast. And yet these are places that have been thrown into disarray by climate change. They are ‘uncanny’ places, for they are familiar homelands and yet at the same time reflect the extreme changes that threaten us as a result of the climate crisis. The disappearance of the Alpine glaciers, the flooding of the North Sea coast, the dieback of the forests. And in a way, they also reflect the inner lives of the three protagonists.

Your protagonists decide to go beyond their research and take action as activists, ranging from TED Talks and public engagement to civil disobedience. At what point does academic responsibility become political action?

I believe the line between the two is blurred. In my film, the meteorologist Özdem Terli jokes: “Physics is left-wing.” In today’s heated political climate, simply citing scientific facts or the laws of nature is often enough to have oneself labelled politically. What is considered “neutral” is being increasingly distorted and restricted by certain political parties and media organisations. Fearing they might not be scientifically neutral, more and more scientists are withdrawing from the public eye and falling silent. Culture is currently facing the same threat.
Sebastian sums it up: “I used to be afraid of being accused of activism. But we are all activists. We are either activists for a world of + or - 3 degrees.” That is the challenge of the climate crisis: failing to act, staying out of it, being “neutral”, means further exacerbating this crisis.

All three protagonists are torn by a powerful inner conflict between knowing and acting. You accompany them even in very personal moments. At what point does the cost of their actions begin to become apparent? And how did you decide how close to get to them and where to maintain a distance?

My documentary films are always a journey and shaped by the protagonists. There is no script beforehand, no defined endpoint, no pre-determined path to get there. The protagonists’ lives dictate the narrative.
It was clear to me that people’s personal responses to the climate crisis would play an important role in the film. But precisely because the personal is not supposed to play a role in scientific work, it wasn’t at all easy to convince the three of them that their personal attitudes were important for our film. It was a delicate process to draw them out of their scientific roles. This was only possible through trust, by spending a lot of time together and listening, rather than simply starting to film straight away with the camera. Even if these are moments of weakness, doubt or failure. Perhaps these are the most striking moments in the film, because they touch on taboos. It is always dangerous to stray from the established path. Doing so makes you vulnerable. By participating in a film like this, the three of them are also making themselves susceptible to criticism.

Your film is powerful, but not overtly emotional. What is your aim: do you want it to inform, move people, or inspire them to take action?

I think that if, as a filmmaker, you try too hard to control how the audience leaves the cinema, you usually end up achieving the opposite. It has always been my aim to keep the film as open as possible. Dissenting voices are heard, questions are asked, and no promises of easy solutions are made. Viewers are invited to think for themselves and develop their own stance. I believe that is what makes cinema special. When we are emotionally moved by the information, it translates into action.

After all these insights and conversations with the scientists who are ‘closest to the issue’, has the film changed your own perspective on the climate crisis?

When you make a film like this, you end up feeling very lonely. Whenever people asked me what my new film was about and I replied, ‘The climate crisis’, there was usually an awkward silence. And I felt compelled to apologise for bringing up this unpleasant topic. Or I was told that the climate issue was over, which is a strange statement, because the issue is certainly not over for us.
A film is always a document of its time. During the period in which I made the film, 2023–2025, we in the Western world experienced a rollback in climate protection. Climate targets were watered down, climate protection laws were repealed. The 1.5-degree target will not be met. The European Union’s Scientific Advisory Board is already warning of a world that is 3–4 degrees warmer. A film about the climate crisis in 2026 must therefore inevitably also be a film about failure. And about farewells. And about how to remain hopeful and keep fighting despite everything. Here, I have learned a great deal from my three protagonists, Nana, Maria and Sebastian. They carry on, not out of naive optimism, but out of hard-won hope and a deep sense of responsibility.

Many thanks to filmmaker Florian Heinzen-Ziob!

Come and see THE WEIGHT OF THE WORLD at DOK.fest Munich 2026. You can find all the screening dates here.
Click here to view the full 2026 film programme.