A Conversation with Johan Rockström

Explaining Planetary Boundaries: An Interview with, 2024 Tyler Prize Laureate Professor Dr. Johan Rockström.

We were honored to speak with 2024 Tyler Prize Laureate Professor Johan Rockström, a pioneer in environmental science and the visionary behind Planetary Boundaries, a scientific guide to help keep the planet in a safe operating space. As the director of the Potsdam Institute for Climate Impact Research (PIK), Professor Rockström’s work has redefined the way we understand and address global sustainability. Here, Professor Rockström sheds light on Planetary Boundaries, the importance of science in safeguarding the future of humanity and pays tribute to the work of his collaborator and friend, the late Australian chemist Will Steffen. 

In a few sentences, could you explain what Planetary Boundaries are?

The Planetary Boundaries are the scientifically identified limits within which humanity can safely operate. The boundaries cover critical environmental processes and act as a navigational chart to ensure the stability of the planet and its ability to support life. The Planetary Boundaries include climate change, ocean acidification, biosphere integrity, stratospheric ozone depletion, atmospheric aerosol loading, biogeochemical flows, freshwater and land systems change. If we push Earth beyond these boundaries, we risk causing irreversible changes and destabilizing the life support on planet earth. By keeping within the boundaries, there’s a high chance of keeping the planet in a positive livable state for humanity.

What does winning the Tyler Prize mean to you?

The Tyler Prize is not only one of the most prestigious environmental science prizes in the world, it’s also one of the world’s first. So, it is a particular honor to get recognition for the science that I’ve been pursuing. But I see this in particular as a recognition of the importance of Planetary Boundary science, which is a broad community effort. It’s really a recognition of 20 years of effort among colleagues around the world: from my previous institution, the Stockholm Resilience Center, my colleagues here at the Potsdam Institute for Climate Impact Research, but also everything that we’ve been doing with the Earth Commission, with Future Earth, with the Earth League. So, collaborations that I’ve been privileged to be involved in for such a long time. So, it’s really a fantastic boost and a recognition that we’re on the right track scientifically. And I’m sure that this recognition, the Tyler Price 2024, will give even more impetus for our science moving forward.

What led you to develop the Planetary Boundaries framework?

The framework stands on three decades of scientific advancements. It’s like we’re standing on the shoulders of giants. Firstly, we had the realization that we had moved into the age of the Anthropocene, where human activities dominate geological forces. We have so much proof that humanity has filled up the entire space available, we are hitting the ceiling of the carrying capacity on planet Earth.

Secondly, we had research showing that planet Earth is a complex self-regulating system, with tipping points. These tipping points are crucial: push the system too far and you can cross a tipping point into a state that no longer helps us. Lastly, and perhaps surprisingly for some: the biggest breakthrough came from insights from paleoclimatology, which provided an important historical context. When we look back at the two ice ages and two interglacials that humanity has lived through, we see that the Holocene was a remarkably stable period in terms of temperature fluctuation. It served as a takeoff point for the modern world as we know it today which has allowed civilization to flourish. So if we want to take a moral responsibility for humanity, the Holocene is the only reference point we have for the desired necessary state of the planet. These three lines of science were brought together in 2007, 2008, and then I was able to invite scientists from across all the scientific disciplines of the Earth sciences to study further, and that is what took us to the Planetary Boundary science.

Six of the nine planetary boundaries have been breached. Why haven’t we experienced catastrophic consequences already?

The boundaries are set with caution and each of the safe boundaries are placed at the lower end of the scientific uncertainty range. The only reason why there is uncertainty is that we don’t fully understand the functioning of the Earth system. If we could interview planet Earth and she could talk to us, she would give us the exact numbers, but sadly, that’s not possible. Breaching the boundaries signals danger rather than an immediate collapse. When you’re in a high-risk zone, that acts as a warning bell. It tells you that this is a place where things are likely to go wrong, but we cannot say exactly when they go wrong, and we cannot say exactly when they go wrong irreversibly. It’s important to think of the Planetary Boundaries as a risk assessment and a warning signal.

You’ve advocated for the United Nations Security Council to adopt the Planetary Boundaries framework. What specific actions would you like to see from the UN?

Firstly, to recognize that planetary sustainability is a security issue. It’s not about environmental protection, it’s about security because staying within planetary boundaries gives us stable societies. Food security and water security reduces conflicts. Placing the planetary boundaries at the United Nations Security Council where it belongs: that’s number one. Number two, the United Nations has the opportunity to show that we need to collectively become stewards of the whole planet. All countries in the world need to keep a continuous monitoring of how things are going on the planet and recognize the joint responsibility of keeping the planet stable.

Considering the urgency, do you believe breaching Planetary Boundaries is comparable to a nuclear-level threat, necessitating a non-proliferation treaty for fossil fuel use?

Yes, indeed. There is already a proposal for a non-proliferation treaty on fossil fuels, which is inspired by Planetary Boundary science for the climate planetary boundary. I think we can be inspired by the nuclear non-proliferation treaty because the threats we’re facing on breaching planetary boundaries constitute an equally large threat to humanity. So having the same kind and scale of action is definitely justified, it’s on par with each other.

Turning our attention to the United States, if you could suggest one policy for President Biden and Secretary Kerry, what would it be?

I would like to see the U.S. as the world’s leading nation, not only on economics and defense and finance, but also on the position of planet Earth. The U.S. wants to be a leader in space, Moon and Mars exploration. I think they now have a particular responsibility to take a lead on governing the whole planet and recognizing that we need to have, like a space program, a new Earth program to monitor and measure the whole planet and to take the lead on a planetary boundary-led security monitoring system. The U.S., under President Biden, has launched the National Nature Assessment. The U.S, could be the first country in the world to do a planetary assessment: no one has done that before.

Reflecting on your extensive collaboration with the late Professor Will Stefan who passed away last year (2023), how important was his work in establishing the Planetary Boundaries framework?

Will Stefan played a pivotal role in conceptualizing and advancing the framework. We spent months working together with crazy brainstorming sessions. His interdisciplinary expertise, particularly in defining the Anthropocene, greatly contributed to our understanding. He was a phenomenal interdisciplinary Earth system scientist. He mattered so much to the work, and we continued to work together after the publication of the first Planetary Boundaries science, developing the framework and updating it together. He’s co-author on the 2023 paper on Planetary Boundary science, which was published after he passed away. So, I think he would be really proud.

For individuals aiming to live within safe Planetary Boundaries, what three actions would you recommend, especially for those living in the minority world or ‘global north’, as those most responsible for our planet’s worsening climate?

First and foremost, educate yourself and engage in conversations about Planetary Boundaries. Recognize the interconnectedness of climate, biodiversity, and nature. Second, avoid seeking silver-bullet solutions. Acknowledge the importance of nature in building resilience. Lastly, strive for honesty in reducing your footprint of carbon, waste, pollutants, and resource consumption. A lot of these changes are win-win: if you eat more healthy food, you tend to reduce pressures on all the nature boundaries plus the climate boundary and of course it’s also good for your health.

Considering the environmental impact, what goes through your mind when you find yourself in a situation that involves significant fossil fuel consumption, such as air travel?

It’s a continuous struggle. Every time I’m forced to step on a flight, I find that really difficult and something that I and my colleagues here at the Potsdam Institute try continuously to reduce as much as we ever can. While we transition towards a fossil fuel-free world, we must recognize the current challenges. Reducing individual impacts, such as travel, is essential. Every effort counts, and I, like many others, continually work towards minimizing my environmental footprint. I take the train as often as possible. I actually don’t have a car myself, so I’m a fanatic cyclist. So, we all try to do as much as we can, but still, it is a problem.

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Discover more about Planetary Boundaries and more about Professor Dr. Johan Rockström here.