Written By Paula Harrison
In December 2024, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) released a groundbreaking scientific report that may change how the world tackles its greatest environmental and societal challenges. The Nexus Assessment (ipbes.net), officially titled the Assessment Report on the Interlinkages Among Biodiversity, Water, Food and Health, is the most comprehensive, evidence-based global assessment of its kind—built on more than three years of research, contributions from 165 leading experts from 57 countries, and a deep synthesis of hundreds of peer-reviewed studies, future scenarios and real-world interventions.
At its core, the Nexus Report delivers one clear message: our crises are connected, and so must be our responses.
The Interlinked Web of Global Crises
Biodiversity loss, water and food insecurity, health threats and climate change are not just interrelated—they are inseparable. As the IPBES Nexus Report outlines, efforts to address one crisis in isolation can undermine progress on another. For example, agricultural intensification may boost food production, but it often comes at the cost of biodiversity loss, increased greenhouse gas emissions, water pollution, and rising health issues such as non-communicable diseases.
Importantly, these crises do not arise in isolation. Indirect drivers—such as unsustainable consumption, economic growth and demographic shifts—intensify the direct drivers of land and sea use change, unsustainable exploitation of resources, climate change, pollution and invasive alien species. Together these drivers create cascading and compounding impacts that propagate across natural and human systems, undermining ecosystem resilience, human well-being, and long-term sustainability.
Critically, the negative impacts of these interlinked crises are unequally distributed, with developing countries, small island nations, Indigenous Peoples and marginalised communities bearing the heaviest burdens, despite contributing the least to global environmental degradation. However, current approaches often fail to address these crises because they are fragmented and siloed, don’t account for the underlying causes, or fail to recognise the interdependencies at play. This leads to conflicting objectives, inefficiencies, perverse incentives and costs, and unintended consequences.
And yet, the evidence from the report is clear: biodiversity underpins our food and water supply, our health and wellbeing, the stability of our climate and our economic prosperity, with more than $58 trillion—over half of global GDP—moderately to highly dependent on nature. Despite this, biodiversity is in steep decline at all scales, across every region of the world. Worse still, our current economic and financial systems perpetuate the problem. According to the report, the world allocates 35 times more funding to activities that harm biodiversity than to those that protect it, resulting in an estimated $10–25 trillion in unaccounted-for externalities—hidden costs reflecting negative impacts on biodiversity, water, health and climate change.
So how can we move towards more sustainable and just futures?
Scenarios for the Future: Modelling Our Choices
The Nexus Assessment analysed 186 future scenarios to understand the likely outcomes of different societal pathways. The findings are unambiguous: “business-as-usual” will not meet global biodiversity, climate or health goals. In addition, pursuing isolated goals—like increasing food production without addressing environmental sustainability—can lead to declines in biodiversity, degraded water resources and worsening climate impacts.
But there is good news: other scenario studies show that nexus-wide benefits with positive outcomes for people and nature are feasible in the future. Such scenarios focus on nexus approaches that combine response options on sustainable consumption and production, ecosystem conservation and restoration, pollution reduction, and integrated climate mitigation and adaptation. These scenarios were found to provide the most consistent co-benefits across the nexus elements, while enhancing resilience and equity. These outcomes offer strong evidence for what can work when interventions are designed with nexus thinking.
The Way Forward: Nexus Thinking
One of the most powerful contributions of the Nexus Assessment is its evaluation of more than 70 response options, each evaluated for their impacts across biodiversity, water, food systems, public health, and climate mitigation and adaptation. These response options were structured into ten broad categories and reflect a diversity of approaches: conserve or halt conversion of ecosystems of high ecological integrity, restore natural and semi-natural ecosystems, manage ecosystems in human-exploited lands and waters, consume sustainably, reduce pollution and waste, integrate planning and governance, manage risk, ensure rights and equity, and align financing.
The report highlights how such response options work better when applied through "nexus approaches" that take account of the interlinkages and interdependencies between sectors and systems holistically to develop integrated and adaptive decisions that aim to maximise synergies and minimise trade-offs.
What the evidence shows is that certain interventions have broad, synergistic benefits across the nexus, with many response options providing positive impacts for all five nexus elements—biodiversity, water, food, health and climate change. Examples of these are:
- Restoration of carbon-rich ecosystems like forests, wetlands, and mangroves, which simultaneously store carbon, support biodiversity, improve water quality, and reduce health risks.
- Sustainable healthy diets, which benefit both human health and the planet.
- Urban green infrastructure, proven to reduce heat island effects, improve air and water quality, and lower the burden of non-communicable diseases.
- Recognition and support of Indigenous food systems, which have demonstrated effectiveness in conserving biodiversity while providing nutrition and community resilience.
To help decision-makers implement these response options, the Nexus Report provides a practical eight-step “roadmap for nexus action”. The roadmap emphasises collaborative diagnosis of nexus challenges and their underlying drivers and interdependencies, co-creation of shared visions to facilitate coordinated and strategic action, and the negotiation and scaling of solutions that deliver benefits across sectors and communities. It highlights the role of inclusive participation and provides evidence that such engagement increases both the equity and effectiveness of responses. The report also identifies more than 200 decision support tools that can be used alongside the roadmap for implementing nexus approaches related to biodiversity, water, food and climate change—although health is commonly not included in these tools—, underscoring the accessibility of actionable solutions.
A Call to Action for All of Us
The message of the IPBES Nexus Report is both urgent and empowering: while the crises we face are daunting, the tools to address them are within our grasp. Integrated, adaptive and inclusive governance—guided by science and supported by diverse knowledge systems—can unlock a cascade of benefits across our planet’s most vital systems.
Whether you're a policymaker, business leader, scientist, farmer, activist or consumer, you have a role to play. As the Nexus Report illustrates, everyone can contribute to building a more just and sustainable future.
Let us not treat nature, climate, water, food, or health as separate issues. The Nexus Report gives us the blueprint to act—and to act together.