07 October 2022

The ecosystem approach and the barrier of state sovereignty in environmental treaties

Thanks to massive advances in science and technology, the last few decades have revolutionised our understanding of the world’s ecosystems and their contribution to human well-being. Dario Piselli explored in his PhD thesis the influence of this unprecedented production of new knowledge on the development of international environmental law. Unfortunately, international environmental law will not effectively benefit from this new knowledge as long as it continues to give a central place to the sovereignty of states over their biological resources.

How did you come to choose your research topic?

This doctoral research project was an attempt to bridge two key interests of mine, namely the science of ecology and international environmental law. For as long as I can remember, I have been fascinated by the concept of ecosystem, which evokes both stunning images of our planet’s diversity and complex mathematical models of ecological dynamics. I recall reading essays such as “The Little Things that Run the World” by Edward O. Wilson and being filled with a sense of wonder at the idea that these dynamics – of which we sometimes understand very little – actually sustain life on our planet.

Today, continuing advances in environmental sciences and monitoring technologies such as satellite observation systems have greatly expanded our knowledge of key ecological processes. At the same time, they have shed light on how deeply human activities are affecting the integrity of the Earth’s ecosystems. When I started my PhD, I began to ask myself whether we, as international law researchers, fully grasp the implications that these scientific advances may have for how multilateral environmental agreements are designed and operate. This immediately seemed to me a very pertinent – if often neglected – question. After all, we cannot hope international environmental law to be effective in protecting ecosystems if its approach to regulating their use neglects how they function in the first place!

Can you describe your thesis questions and the methodology you use to approach those questions?

In order to study how multilateral environmental agreements incorporate scientific knowledge about ecosystems, I decided to focus on a concept that sits at the boundary of science and international environmental law. This concept, known as the “ecosystem approach”, is frequently mentioned in the work of international treaty bodies, with the ostensible purpose of embracing a more integrated perspective on the conservation and use of ecosystems. However, its actual impact on this area of international law has never been fully assessed. In my study, I decided to explore three questions in relation to the approach:

  1. What types of legal obligations could theoretically be derived from the science that informs the ecosystem approach?
  2. What type of obligations have been adopted in practice by environmental treaties seeking to apply an ecosystem approach?
  3. If there is found to be a gap between the science underpinning the approach and the legal obligations used to implement it, what are the potential reasons for this gap?

Because these are fundamentally interdisciplinary questions, I tried to address them through a methodology which combines traditional doctrinal analysis of legal instruments, insights coming from ecology and other sustainability sciences, and a historical account of the interface between scientific advances and international environmental law. The specific treaties I looked at include both general instruments, namely the Convention on Biological Diversity (CBD), and sectoral agreements in areas such as fisheries management, marine pollution, and freshwater resources.

What are your major findings?

I show that while environmental treaties that formally endorse the ecosystem approach have indeed adopted more integrated regulatory techniques, they have mainly done so through “procedural” provisions which only prescribe states a certain conduct – for example the obligations to conduct environmental impact assessment or to use the best available scientific knowledge when adopting decisions which may have an impact on ecosystems. By contrast, these agreements have so far failed to introduce “substantive” obligations requiring countries to protect the integrity of their ecosystems vis-à-vis the international community, which is arguably the core dimension of the ecosystem approach and is heavily supported by what the science currently tells us about the cascading effects that ecosystem degradation can have across national borders and spatial scales.

From this perspective, a key argument of the thesis is that this is not merely a problem of tweaking regulatory techniques in this or that treaty. Despite gradual advances, such as the possible interpretation of duties to co-operate and prevent environmental harm as relating to ecosystems, rather than individual natural resources, the entire structure and daily practices of international environmental law are still premised on the principle that states enjoy the sovereign right to exploit the biological resources under their national jurisdiction. This represents a formidable structural limitation to the uptake of a “strong” version of the ecosystem approach in environmental treaties.

Can you give us examples of treaties or policy agendas that are currently trying to address this state of affairs? 

The issue of ecosystem conservation and restoration features prominently in a growing number of international policy agendas, ranging from the post-2020 framework of the CBD to the European Green Deal. Biodiversity and ecosystems have now moved to the fore of political discussions just as it happened, years ago, to climate change. However, it is clearly not enough for these agendas to formally endorse the notion of ecosystem approach. Taking an ecosystem-wide perspective in international environmental law requires addressing the structural limitations that hinder progress in implementing such an approach – most notably, a lack of ambition in setting “hard” limits to our use of ecosystems and the failure to fully recognise countries’ duty to protect their integrity. With respect to the post-2020 framework of the CBD, for example, the thesis argues that even the likely inclusion of an ambitious target to protect ecosystem integrity could mean little, at the level of implementation, if the CBD’s emphasis on state sovereignty continues to prevent the adoption of stronger mechanisms for monitoring and compliance.

But how can this emphasis on state sovereignty be overcome?

As I mentioned, one of the central contentions of my thesis is that ecosystems cannot effectively be governed through an architecture of multilateral environmental agreements that is still, more or less rigidly, upholding the sovereignty of states over their biological resources. Understandably, there have been important historical reasons that explain why this principle remains so relevant, for example in relation to the interests of “Global South” countries towards self-determination. However, the fact remains that the integrity of the entire biosphere may be at risk if states continue to destroy ecosystems at the current pace. This means that there should, at the very least, be a significant political push towards stronger compliance mechanisms in environmental treaties and greater cooperation in the regulation of ecosystems, including through forms of joint management and knowledge and technology transfer.

What are you doing now in your post-PhD life? 

Since completing my PhD journey, I have moved to Copenhagen, where I am now working as an expert in environment and health at the European Environment Agency (EEA). This is an agency of the European Union which assesses the state of the environment in Europe and supports European and national decision-makers in the development, implementation and evaluation of environmental policies. At the EEA, I follow dossiers relating to the sustainability of food systems and the interface between biodiversity and human health, among other things. In the near future, I also plan to work towards the publication of my PhD manuscript as a monograph. 

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Dario Piselli defended his PhD thesis, “Protecting Ecosystem Integrity in the Age of Planetary Boundaries: Science, International Environmental Law, and the Ecosystem Approach”, in February 2022. The jury members were Adjunct Professor Jorge Enrique Viñuales (chair and internal examinator), Associate Professor Anne Saab (supervisor), and Professor Eloise Scotford, Faculty of Laws, University College London, UK.

Access to the PhD thesis:
Members of the Geneva Graduate Institute can access the PhD thesis on this page of the Institute’s repository. Others may contact Dr Piselli at

Citation of the PhD thesis:
Piselli, Dario. “Protecting Ecosystem Integrity in the Age of Planetary Boundaries: Science, International Environmental Law, and the Ecosystem Approach.” PhD thesis, Graduate Institute of International and Development Studies, Geneva, 2022.

Interview by Nathalie Tanner, Research Office.
Banner picture: excerpt from an illustration by Willem Tims/