Why was I interested in interviewing Thijs? He is an Associate Professor of Environmental Science at the Institute of Environmental Sciences (CML) at Leiden University and Programme Director of the BSc Science for Sustainable Societies. His research focuses on understanding the impacts of emerging and cumulative environmental stressors, particularly plastic pollution, across a wide range of ecosystems and species, from plants and zooplankton to marine mammals. Beyond his scientific contributions, Thijs is deeply committed to education and interdisciplinary learning. Through his leadership of one of Leiden University’s most innovative sustainability programmes, he works to equip students with the scientific knowledge, critical thinking skills, and societal awareness needed to address some of the most complex environmental challenges of the twenty-first century.
This interview offers much more than an exploration of environmental science; it provides a thoughtful reflection on how curiosity, education, and empathy can shape a meaningful career dedicated to sustainability. Thijs shares insights not only into pressing issues such as environmental governance, planetary boundaries, food systems, and climate action, but also into the human dimensions of these challenges, including hope, responsibility, resilience, and the importance of agency. Combining personal stories with reflections on science, teaching, and social change, the conversation reveals how sustainability is ultimately about people as much as it is about ecosystems. Readers will come away with a deeper understanding of the environmental challenges facing our world, as well as a renewed sense that meaningful change remains possible when knowledge is paired with action.
Here’s our exchange:
Where are you originally from, and what aspects of your childhood there most shaped who you are today?
I was born in Rotterdam, a large port city in the Netherlands, but many of my childhood memories are actually set outside the city. My family often spent time camping on farms or staying in a small beach house along the Zeeland coast. Those experiences immersed me in nature and gave me a strong appreciation for the outdoors from an early age.
In fact, because of the time I spent on farms, my childhood dream was to become a farmer. That did not quite happen, but the ambition directly influenced my choice of study: Plant Sciences at Wageningen University, one of the world’s leading agricultural universities. Looking back, the connection to land, crops, and outdoor life that I developed as a child became the foundation of my entire scientific career. Even today, much of my work is driven by a fascination with how humans interact with natural systems and how we can manage those relationships more sustainably.
How would you describe your family environment growing up, and who were the most influential figures in your early life?
I grew up in a very warm and caring family with two brothers. Although both of my parents had demanding jobs, they always made time for us and were actively involved in our lives. There was a strong sense of support, but also a clear expectation that we would learn to think for ourselves and take responsibility for our decisions.
My parents and my grandfather were probably the most influential figures in my early life. They provided guidance, encouragement, and perspective whenever I needed it. What I appreciated most was that they helped me reflect on important choices without ever trying to make those choices for me. That balance between support and independence shaped how I approach both personal and professional decisions today.
Were there particular family or cultural traditions that played a lasting role in shaping your values or worldview?
There is no single family tradition that immediately stands out, but if I think about broader Dutch traditions, the so-called polder model comes to mind. Historically, people living in the Netherlands had to work together to manage water and maintain dikes, regardless of their differences. Over time, this evolved into a culture of consultation, dialogue, and compromise.
The idea that people with different interests should sit around the table and keep talking until a workable solution emerges has had a lasting influence on how I view collaboration. It has shaped my approach to leadership, teamwork, and interdisciplinary research, where finding common ground is often essential for progress.
What initially drew you to the field you chose to study, and was there a moment when you realized it was the right path for you?
My connection to outdoor life and the land was the starting point. As I mentioned earlier, I wanted to become a farmer, which was perhaps not the most realistic ambition for someone growing up in a major city. I even remember feeling slightly embarrassed to tell my high school friends about it. At that age, farming did not exactly seem like the coolest profession.
Over time, however, my interests expanded beyond agriculture. As I became more aware of major environmental challenges, I developed a growing interest in environmental science and sustainability. One memory that stands out is a presentation I gave in primary school about a major environmental disaster—I believe it was related to a chemical spill involving BASF in the 1990s. Preparing that presentation made me realize how profoundly human activities can affect ecosystems.
During my university studies, I increasingly focused on sustainable agriculture and alternative approaches to food production. That was the point where my interest in farming and my concern for environmental issues truly came together. Looking back, it became clear that this intersection was where I wanted to build my career.
At what age did you begin working, and what did your first job teach you about responsibility or independence?
I started working when I was twelve years old, delivering newspapers. It may seem like a simple job, but it taught me some very important lessons. Getting up at six in the morning, regardless of the weather, and making sure the newspapers were delivered on time every day required discipline and consistency.
More than anything, it taught me the value of reliability. Sometimes responsibility is not about doing something extraordinary; it is about showing up every day, doing what you said you would do, and understanding that others depend on you. That lesson has stayed with me throughout my career.
How would you describe your current professional role, and what aspects of it do you find most meaningful?
I am an Associate Professor of Environmental Science at the Institute of Environmental Sciences (CML) at Leiden University, and Programme Director of the BSc Science for Sustainable Societies. My research focuses on developing innovative, robust, and standardized methods to study the effects of novel and cumulative environmental stressors, particularly plastic pollution, across systems ranging from plants and zooplankton to marine mammals.
What I find most meaningful is the relationship between research and teaching, and the fact that the exchange runs in both directions. Research-led teaching means that I bring my own research questions directly into the classroom, allowing students to engage with science at its frontier rather than simply learning established textbook knowledge.
At the same time, teaching-led research is equally important. The curiosity, creativity, and fresh perspectives of students often influence and advance my research agenda. I have seen classes of two hundred students collectively remove thousands of pieces of plastic from local beaches and create political art projects that reshape public conversations about sustainability. I have also seen undergraduate theses develop into co-authored publications in international journals. Those moments remind me that education and research are not separate activities; they reinforce one another in powerful ways.
How do you assess the risk that sustainability science becomes technocratically driven, prioritizing measurable environmental indicators while sidelining questions of power, justice, and political feasibility?
It is a real risk, and one I take seriously. Sustainability is fundamentally rooted in the interaction between the natural sciences, the social sciences, and the humanities. At times, we have lost sight of that broader foundation.
Environmental science is very good at producing measurable indicators: concentrations, thresholds, emissions data, model outputs, and so on. These metrics are essential, but they do not tell the whole story. A sustainability transition that focuses exclusively on technical indicators while neglecting social realities will struggle to succeed, regardless of how robust the underlying science may be.
Questions of power, justice, equity, and political feasibility are not secondary concerns. They often determine whether a proposed transition is accepted, implemented, and sustained over time. This is precisely why I am excited about the BSc Science for Sustainable Societies. The programme intentionally combines natural science, social science, governance, and design thinking. Students learn from the beginning that environmental indicators are important, but they are never sufficient on their own.
In interdisciplinary sustainability programs, how do you ensure that natural science perspectives do not dominate at the expense of social, cultural, and ethical dimensions of environmental change?
The key is to build interdisciplinarity into the structure of the programme rather than relying on goodwill alone. In practice, we achieve this through co-teaching. Two lecturers from different disciplines are present in the classroom at the same time, engaging with the material together rather than teaching separate modules in isolation.
This approach creates a dynamic environment where assumptions can be challenged immediately. A natural scientist cannot simply default to a purely technical framing when a colleague from governance, anthropology, sociology, or ethics is present to offer a different perspective.
Importantly, this process is not always comfortable. We do not always interpret issues in the same way, and we do not always share the same priorities or values. However, those disagreements are not hidden from students. They become part of the learning experience. Students see firsthand how complex sustainability challenges require dialogue across disciplines and how productive disagreement can contribute to better solutions.
To what extent do current planetary boundaries frameworks risk oversimplifying complex socio-ecological systems, and how should they be revised to better account for regional inequality and historical responsibility?
The planetary boundaries framework is extremely valuable because it captures the interconnectedness of environmental challenges while providing concrete and understandable boundaries. Its clarity is one of the main reasons it has become so influential. It is intuitive, visually compelling, and communicates urgency in a way that both policymakers and the public can engage with.
However, the framework was designed primarily to identify biophysical limits. It was not originally intended to address the social, political, and historical dimensions of environmental change. As a result, it cannot fully explain who is responsible for crossing those boundaries or who bears the consequences.
Many scholars have worked to complement the framework with additional perspectives. Kate Raworth’s Doughnut Economics is an excellent example. By combining planetary boundaries with a social foundation that addresses human wellbeing and basic needs, it creates a more holistic picture of sustainability. Rather than replacing planetary boundaries, such approaches help situate them within broader discussions about equity, justice, and development.
How should environmental scientists engage with activism without undermining their credibility, particularly when scientific evidence clearly supports urgent political action?
I believe the credibility of environmental scientists depends on being very clear about what the evidence shows and equally clear about where evidence ends and value judgments begin.
As scientists, we can state with confidence when data demonstrate that certain contaminants are increasing, that ecosystems are being harmed, or that cumulative environmental pressures are reaching dangerous levels. Those conclusions are based on evidence. Deciding which policy response is preferable, however, involves additional considerations, including economics, social priorities, ethics, and politics.
That said, scientists also have a responsibility to communicate the implications of their findings. If available evidence clearly demonstrates that current policies are insufficient to address objectively measurable impacts, we should continue highlighting that gap clearly, accurately, and persistently. This is not activism in the partisan sense; it is part of our responsibility to ensure that scientific knowledge remains visible and relevant within public decision-making processes.
The challenge is to remain rigorous, transparent, and honest about where scientific evidence informs the discussion and where societal choices ultimately need to be made.
In your experience as a programme director, how do you address the tension between training students for employability and equipping them to challenge the economic systems driving environmental degradation?
I do not really see this as a tension; I see it as an opportunity. Yes, our students will enter and operate within existing economic systems, but those systems are not static. They contain a growing number of individuals, organisations, and sectors that genuinely want to contribute to change. There is real space to help create social tipping points from within.
Our role is to give students the knowledge, confidence, and agency to become part of that transformation. Alongside disciplinary knowledge, we place strong emphasis on transferable skills: working effectively in diverse teams, navigating complex and sometimes polarised debates, communicating across disciplinary boundaries, and understanding the interactions between science, society, and technology. These are valuable skills for employers, but they are also exactly the skills needed to challenge assumptions, build coalitions, and drive change from wherever students ultimately work.
How do you respond to critiques that sustainable development discourse often preserves the status quo by framing systemic problems as issues of efficiency, innovation, or individual behavior?
I think that critique has considerable merit. Innovation can certainly help, and individual behaviour does matter, but neither is sufficient on its own. Many environmental challenges are rooted in systemic structures that shape how societies produce, consume, and distribute resources.
What is ultimately required is systemic change, supported by effective governance and collective action. If we frame sustainability solely as a matter of technological efficiency or personal responsibility, we risk overlooking the political, economic, and institutional drivers of environmental degradation. Better technologies and more conscious consumers are important, but they cannot substitute for broader societal transformation.
What responsibilities do universities in the Global North have when teaching sustainability models that may be ecologically sound but socially disruptive or inappropriate in other contexts?
This is an extremely important question. If universities engage internationally, that engagement must be based on genuine collaboration rather than the export of predetermined solutions. My own approach has been to build research and teaching partnerships with local organisations and institutions, recognising that valuable knowledge already exists within those communities.
Knowledge should flow in both directions. Too often, sustainability solutions are developed within European or North American contexts and then assumed to be universally applicable. In reality, ecological, social, cultural, and political conditions vary enormously.
We also bring these discussions directly into the classroom. Students engage with debates on fortress conservation, alternative knowledge systems beyond Western science, and the broader movement to decolonise science. A sustainability model may appear effective on paper and still be socially disruptive, unjust, or simply inappropriate in a specific context. Students need to learn to ask those questions before assuming that solutions can be transferred unchanged from one place to another.
How can environmental science education avoid producing “sustainability generalists” who understand problems broadly but lack the depth needed to drive real systemic change?
I think what is needed is not someone who knows everything, but someone who knows how to bring the right expertise to the table. Sustainability challenges are too complex for any individual to master every relevant discipline.
The key skill is being able to communicate with specialists, understand different forms of expertise, and critically evaluate what is being proposed. Deep knowledge remains essential, but access to information has never been easier than it is today, especially with advances in AI and digital technologies.
What increasingly makes the difference is the ability to use information critically, identify gaps in understanding, and ask the right question at the right moment. In many ways, sustainability professionals act as translators and connectors between fields, helping expertise come together in productive ways.
To what extent should environmental policy be guided by precaution when scientific uncertainty remains high but the potential consequences are irreversible?
I would challenge the premise slightly. In many cases, the scientific uncertainty is not actually as high as it is sometimes portrayed. Exact outcomes can never be predicted with complete certainty, but there is overwhelming scientific consensus regarding many environmental risks associated with biodiversity loss, pollution, and climate change.
The evidence demonstrating harm to ecosystems, societies, and future generations is already substantial. In that sense, we have sufficient knowledge to justify action. The real challenge is no longer deciding whether action is necessary, but determining which actions are most effective, equitable, and politically feasible.
How do you see the role of quantitative environmental modeling evolving in light of growing recognition that uncertainty, nonlinearity, and surprise are inherent features of Earth systems?
This is not my primary area of expertise, so I would hesitate to make a strong technical argument. However, from the perspective of environmental science more broadly, one lesson is clear: the natural world continues to surprise us.
There are many examples of this. Scientists have travelled to remote Arctic regions expecting to find pristine environments, only to discover unexpectedly high concentrations of contaminants transported there through atmospheric circulation. Similar surprises occur when ecological systems respond in ways that were not anticipated.
For that reason, I believe quantitative models will continue to improve and remain essential tools. At the same time, they should be developed and interpreted with humility. Uncertainty is not simply a limitation to be eliminated; it is an inherent feature of complex systems. Models should help us understand possibilities and risks while recognising that Earth systems can still behave in unexpected ways.
How can sustainability science meaningfully incorporate indigenous and local knowledge without instrumentalizing it or stripping it of its cultural context?
By treating it as a genuine partner in the scientific process rather than as a source of information to be extracted. Meaningful engagement requires listening, dialogue, and mutual respect.
Indigenous and local knowledge systems often represent generations of observation and interaction with specific environments. They should not simply be translated into scientific data points while ignoring their cultural and historical foundations.
A good example is New Zealand’s Vision Mātauranga policy, which requires applicants for major national research funding to explain how their projects engage with Māori knowledge and communities. The goal is not simply inclusion, but partnership. That distinction is crucial if we want knowledge systems to interact in a way that is both respectful and productive.
In what ways does the current emphasis on green growth limit our imagination of alternative socio-economic futures compatible with ecological limits?
This is not my own field of expertise, so I will not claim a strong theoretical position. However, I do think we should be cautious about framing every discussion in terms of growth.
Sustainability is not only about increasing economic output while reducing environmental impacts. It is also about questions of fairness, access, wellbeing, and the distribution of resources. A sustainable future should not be measured solely by aggregate growth figures, but by whether prosperity and opportunity are shared more broadly across society.
Focusing exclusively on growth risks narrowing our imagination and limiting discussions about alternative ways of organising economies and societies within ecological limits.
How should sustainability curricula confront the emotional and psychological dimensions of ecological crisis, including eco-anxiety and moral distress among students?
Directly, and without minimising those emotions. Eco-anxiety and moral distress are understandable responses to learning about large-scale environmental challenges. Ignoring them does not make them disappear.
One of the most effective responses is to give students agency. Projects such as beach clean-ups, citizen science initiatives, or political art interventions allow students to translate concern into meaningful action. That shift is important because it transforms anxiety from something paralysing into something productive.
At the same time, students need spaces where they can openly discuss these emotions and recognise that many of their peers share similar concerns. Hope is not created by pretending problems are smaller than they are; it comes from recognising that action is still possible.
What does “sustainable societies” mean in practice when sustainability transitions are likely to produce winners and losers across regions and generations?
It means acknowledging from the outset that sustainability transitions are not automatically win-win processes. Some communities, industries, regions, and generations will bear greater costs than others.
A serious sustainability education must prepare students to identify these uneven impacts and engage with the difficult ethical and political questions they raise. Too often, sustainability is presented as a universally beneficial process, but reality is more complicated.
Understanding who benefits, who bears costs, and how those costs can be managed fairly is a central part of building truly sustainable societies. Sustainability is not just about environmental outcomes; it is also about justice and legitimacy.
How do you evaluate success in sustainability education when meaningful impact may only become visible decades after students leave the university?
In many ways, you cannot evaluate it directly, at least not while students are still in the programme. The most meaningful impacts often emerge years or even decades later.
What I look for instead is whether graduates continue to engage with sustainability wherever they go. Whether they work in NGOs, government agencies, businesses, research institutions, politics, or entirely different sectors, do they continue raising these issues and integrating sustainability into their decisions?
We can already see evidence of this happening. Sustainability and environmental science are relatively young fields, becoming mainstream only in recent decades. Yet graduates from these programmes have helped place environmental challenges on both local and global agendas. Their collective impact is visible across society, even if it is difficult to measure through traditional educational metrics.
Has there been a book, film, or work of art that significantly influenced the way you see the world or think about your work?
One book that had a significant impact on me is A Short History of Nearly Everything by Bill Bryson.
What I particularly appreciate about the book is that it presents science as a profoundly creative and human endeavour. It is driven by curiosity, persistence, and a desire to understand the world, rather than by certainty or authority.
Perhaps most importantly, it portrays many of history’s great scientists as ordinary people with quirks, flaws, and moments of failure. That perspective makes science feel more accessible and reminds us that discovery is often a messy and deeply human process.
Looking at younger generations today, what gives you the greatest sense of hope, and what concerns you the most?
What gives me hope is something I see regularly in my own classroom. When students are given genuine agency and meaningful opportunities to contribute, many demonstrate an impressive determination to make a difference.
Despite the scale of environmental challenges, they are often remarkably creative, pragmatic, and solution-oriented. They do not necessarily become paralysed by the crisis; instead, they look for ways to engage with it.
What concerns me most is the growing number of people who seem disconnected from these issues altogether. The challenge is not simply convincing those who already care. It is finding ways to engage those who feel excluded, overwhelmed, sceptical, or indifferent. If we are serious about sustainability transitions, we need to reach beyond our existing audiences.
If you could spend a full day with any historical figure, who would you choose, and what questions would you want to ask them?
I would choose Jane Goodall.
I would be fascinated to learn how she sustained her commitment and energy over such an extraordinary career. She has spent decades combining scientific research, conservation, education, and public engagement, often in the face of significant challenges.
I would ask her how she maintained hope during difficult periods, how she dealt with setbacks and disappointments, and what kept her motivated to continue pushing for change year after year. Those lessons seem particularly relevant today.
If you were asked to teach a class on a subject completely unrelated to your profession, what would it be, and what would you hope students take away from it?
I would choose law. Not necessarily environmental law, but the broader question of how societies translate knowledge into action.
One of the lessons I have learned is that understanding a problem does not automatically lead to change. Law provides mechanisms that can turn knowledge into enforceable action, whether the issue is environmental protection, social justice, or public health.
What I would hope students take away is the importance of integrating ethics into whatever field they pursue. Knowing that something is wrong is only the beginning. The more difficult question is what we are willing to do about it, and whether we are prepared to act rather than simply look away.
If you could ensure that one human value is never lost in society, which value would you choose, and why?
Empathy.
Not only empathy for other people, but also for animals, ecosystems, and the broader biomes of which we are all a part. Many of the environmental and social challenges I work on ultimately stem from an inability, or unwillingness, to consider the perspectives and wellbeing of others.
At its core, sustainability requires us to think beyond ourselves, beyond our immediate interests, and beyond the present moment. Empathy creates the foundation for that broader perspective. If we could preserve that one value, I suspect many of the others would follow naturally.
Humanity is facing radical changes. To name just ten: geopolitical instability, climate change, economic inequalities, technological risks, public health challenges, political polarization, resource scarcity, humanitarian crises, misinformation, and disparities in global healthcare access. If, in an imaginative exercise, you had the power to solve one of these problems, which one would you choose first and why?
Given my own field of expertise, I would choose the current global food production system. It is not always highlighted as a standalone issue, but in many ways it sits beneath a large number of the environmental and social challenges we face today.
Our food system is largely oriented toward maximizing quantity rather than optimizing quality, resilience, or sustainability. That single focus creates enormous pressures across multiple planetary boundaries, contributing to climate change, biodiversity loss, freshwater depletion, soil degradation, and nitrogen and phosphorus pollution. At the same time, it is deeply connected to social issues such as inequality, resource scarcity, food insecurity, and, in some cases, humanitarian crises.
Of course, transforming the food system would not solve every problem overnight. However, it would address one of the most powerful underlying drivers of environmental degradation and social instability. If we could fundamentally rethink how and why we produce food, the positive effects would ripple across many other areas of society and the environment.
What do you believe human beings owe one another, both as individuals and as members of a global society?
I think we owe one another the willingness to look beyond our own immediate horizon, and even beyond our own generation or lifetime. That is not always easy. Human beings naturally focus on the present because we all have immediate concerns, responsibilities, and challenges that require our attention.
At the same time, we have a responsibility to consider the consequences of our actions for others, including people we will never meet and generations that have not yet been born. The challenge is finding a balance between living fully in the present and acting responsibly toward the future.
For me, that balance means being conscious of the footprint of our choices today while leaving behind a world that remains livable, equitable, and full of opportunity for those who come after us. In many ways, sustainability is simply another expression of that responsibility.
Interviews often focus on successes. Could you share something from 2025 that did not unfold as you expected, and what that experience taught you?
Looking back at 2025, there were plenty of things that did not go the way I had hoped. A grant application was unsuccessful. A paper was rejected. A course did not run as smoothly as I wanted. More importantly, there was also a serious accident involving a loved one, which naturally had a much greater impact than any professional setback.
I think disappointment is a normal and healthy response to these experiences. In fact, I often tell my students the same thing: if something matters to you, it is perfectly reasonable to feel upset when it does not work out. Otherwise, it might suggest you never really cared in the first place.
The important part is what happens next. Allow yourself time to process the disappointment—whether that is a day, a week, or however long you need—but then shift your focus toward solutions and the next opportunity. Failure, rejection, and setbacks are not exceptions in academic life; they are part of the process. Learning how to recover from them is often just as important as learning how to succeed.
Are there any personal or professional goals you feel comfortable sharing for 2026?
One project I would very much like to develop is a website dedicated to stories of hope and positive change. The idea would be to create a growing database of real-world examples showing that meaningful progress is happening, often in places and ways that receive little public attention.
Importantly, I would like students to actively contribute to the platform by identifying and documenting these stories themselves. Throughout this interview, I have spoken about the importance of agency and the danger of people, particularly younger generations, becoming disconnected or overwhelmed by environmental challenges.
A resource like this could help counter that sense of helplessness. It would not ignore the seriousness of the problems we face, but it would remind people that solutions exist, that progress is possible, and that individuals and communities around the world are already making a difference.
When you imagine the final moments of your life, what kind of news would you most hope to hear, and why?
Like most people, what I hope for is simply to be surrounded by those closest to me. I hope the only news that reaches me is personal and close to home—not updates about global affairs, conflicts, or the constant noise of the wider world. We are already inundated with information, much of it amplified through social media, and I make a conscious effort to protect myself from that. I am not on social media, and I am deliberate about where and how I consume news. When those final moments come, I hope that remains true: that my attention is focused not on the world at large, but on the people I love most.