Sustainability Hierarchy: Prioritizing Survival and Equity

Sustainability is one of the most widely used words in environmental policy, business strategy, and everyday conversation. But what does it actually mean – and more importantly, how do we decide what sustainability issues matter most? Not all sustainability concerns carry the same weight. Some threaten our very survival as a species, while others are about preferences and aesthetics. The sustainability hierarchy, proposed by Julian Marshall and Michael Toffel, offers a structured way to prioritize these concerns – from the most urgent existential threats down to quality-of-life improvements. This framework draws a compelling parallel with Maslow’s hierarchy of needs and also challenges how corporations define sustainability.

What is the sustainability hierarchy? 🔗

In their 2005 paper published in Environmental Science & Technology, Julian Marshall and Michael Toffel proposed a four-level framework to organize the wide range of issues that fall under the umbrella of sustainability. They argued that sustainability issues differ dramatically in urgency, severity, and consequences – and that lumping them all together under one vague term weakens the concept’s usefulness. Their sustainability hierarchy classifies unsustainable actions based on their potential to cause harm at four distinct levels, with the most critical threats forming the foundation.

Level 1: Threats to human survival 🔗

The base of the hierarchy addresses actions that could endanger the survival of the human species. These are existential-level threats – scenarios where ecosystem functions that sustain all human life could collapse. Think of catastrophic climate disruption, the depletion of the ozone layer, or the destruction of ecosystems that regulate Earth’s atmosphere and water cycles. At this level, the stakes could not be higher. If the ecological systems supporting human life fail, nothing else on the hierarchy matters. This is why Marshall and Toffel placed it as the foundational, non-negotiable priority of any sustainability agenda.

Level 2: Impairment of human health 🔗

The second level deals with actions that impair human health without necessarily threatening species-wide survival. This includes exposure to toxic pollutants, contaminated water supplies, air pollution in urban centres, and the health consequences of environmental degradation. According to the Lancet, biodiversity loss is itself a growing health crisis – the destruction of ecosystems undermines the natural resources on which medicine, nutrition, and disease regulation depend. Pharmaceutical drugs derived from natural products, traditional medicines used by over 80% of the global population, and the emergence of zoonotic diseases are all directly linked to the health of our ecosystems. Level 2 recognises that even when humanity’s collective survival is not at stake, widespread harm to human health demands urgent action.

Level 3: Species extinction and human rights violations 🔗

Level 3 broadens the scope to include species extinction and violations of human rights. The current biodiversity crisis makes this level acutely relevant. The World Wildlife Fund estimates that the current species extinction rate is between 1,000 and 10,000 times higher than natural background rates. The 2024 Living Planet Report found that monitored wildlife populations have declined by an average of 73% over the past 50 years. Meanwhile, the United Nations warns that human activities are driving extinction at tens to hundreds of times the rate seen over the past 10 million years, with over 400 vertebrate species lost in just the last century.

On the human rights side, this level encompasses actions that violate fundamental rights – forced displacement due to environmental destruction, denial of access to clean water, and the dispossession of indigenous communities from their ancestral lands. Species extinction and human rights are placed together at this level because both represent irreversible losses that diminish the planet’s ecological and social fabric.

Level 4: Quality of life and values-based concerns 🔗

The top level of the hierarchy covers actions that reduce quality of life or conflict with cultural values, beliefs, and aesthetic preferences. This includes desires for scenic open spaces, recreational access to wilderness, and broader social justice goals. While these concerns are entirely legitimate, Marshall and Toffel argued that including them under the sustainability label dilutes the concept. They contended that for sustainability to remain scientifically and politically meaningful, these value-driven issues – which vary across cultures and evolve over time – should be addressed separately rather than treated as core sustainability challenges.

The Maslow connection: why foundations come first 🔗

Marshall and Toffel explicitly drew an analogy between their sustainability hierarchy and Abraham Maslow’s hierarchy of needs. Maslow’s well-known psychological framework holds that basic physiological needs like food, water, and shelter must be met before a person can focus on higher-order needs like belonging, esteem, and self-actualisation. The same logic applies here: ecological survival and human health form the foundation that must be secured before societies can meaningfully pursue higher-order sustainability goals.

This parallel is more than just a neat comparison. The Brundtland Commission’s foundational definition of sustainable development – meeting present needs without compromising future generations’ ability to meet theirs – is itself built around the concept of “needs,” with explicit priority given to the essential needs of the world’s poor. The idea of intergenerational equity is central to both frameworks. Just as Maslow argued that unmet lower-level needs dominate motivation, the sustainability hierarchy suggests that ignoring existential ecological threats while pursuing quality-of-life improvements is fundamentally misguided.

However, there is an important nuance. Maslow noted that once existing needs are addressed, new aspirations rise to prominence. Marshall and Toffel observed the same dynamic in sustainability: societies that have secured basic survival and health begin demanding environmental amenities, social justice, and aesthetic values. This is natural – but it also creates the risk that Level 4 concerns consume political attention and resources while Level 1 and Level 2 threats remain unresolved for vulnerable populations elsewhere.

Corporate sustainability: where the gap lies 🔗

One of the most pointed implications of the sustainability hierarchy is its critique of corporate definitions of sustainability. Much of what passes for corporate sustainability today focuses on efficiency improvements, reporting metrics, and brand reputation – areas that, in the hierarchy, would fall into Levels 3 and 4 at best. The ecological foundations that sustain human survival and health are rarely centred in corporate sustainability frameworks.

Whiteman, Walker, and Perego argued in a 2013 paper in the Journal of Management Studies that corporate sustainability scholarship needs to more closely integrate ecological science. They pointed out that corporate sustainability research often neglects ecological systems and their interactions with business activities. Three planetary boundaries – climate change, biodiversity loss, and nitrogen cycle disruption – are already under severe pressure, yet corporate sustainability metrics rarely measure how firms impact these critical processes.

The dominant triple bottom line framework – which balances economic, social, and environmental performance – has also faced criticism. Scholars have noted that in practice, companies frequently prioritise the economic dimension, treating environmental and social goals as secondary or as marketing opportunities. Some firms meet environmental regulations on paper while engaging in practices like carbon offsetting that do little to reduce actual emissions. Research on stages of corporate sustainability has found that most companies operate within a narrow, business-case understanding of the concept – one that focuses on shareholder value and competitive advantage rather than genuine ecological health.

Shareholder value vs. ecological reality 🔗

The tension between shareholder value and ecological sustainability is a recurring theme. Corporate sustainability, in practice, often means adapting environmental language to business goals – reducing waste to cut costs, investing in renewable energy to hedge against fuel price volatility, or improving supply chain transparency to manage reputational risk. These are positive steps, but they do not necessarily address the lower levels of the sustainability hierarchy. A company can be “sustainable” by corporate standards while its operations contribute to biodiversity loss, water contamination, or the displacement of rural communities.

This disconnect matters especially for rural livelihoods. Many of the world’s poorest communities depend directly on ecosystem services – forests, fisheries, soil fertility, and freshwater – for their daily survival. When corporations extract resources or alter landscapes without accounting for these dependencies, they may improve their own sustainability metrics while undermining the ecological foundations that support millions of people. The Brundtland Commission’s emphasis on the “essential needs of the world’s poor” was meant to prevent exactly this kind of trade-off, but it is routinely overlooked in corporate sustainability practice.

Why prioritisation matters now 🔗

The sustainability hierarchy is not just an academic exercise. It offers a practical framework for allocating limited resources – financial, political, and scientific – toward the issues that matter most. The evidence for ecological urgency is overwhelming. The WWF’s 2024 Living Planet Report documents a 73% decline in monitored wildlife populations since 1970, driven primarily by habitat loss and unsustainable food systems. The Arctic is warming four times faster than the global average. Multiple Earth-system tipping points – from the collapse of ocean currents to the loss of Arctic summer sea ice – loom closer with each passing year.

Against this backdrop, the sustainability hierarchy reminds us that not all sustainability concerns are equally urgent. Debates about eco-friendly packaging and green building certifications are worthwhile – but they should not crowd out action on climate destabilisation, mass extinction, and the collapse of ecosystem functions that billions of people depend on. The framework asks a simple but powerful question: are we securing the foundation before decorating the upper floors?

Applying the hierarchy to policy and practice 🔗

For policymakers, the sustainability hierarchy suggests a clear order of priorities. Government spending, international agreements, and regulatory attention should first address Level 1 threats – the systemic risks to human survival from climate change, ocean acidification, and the degradation of critical biogeochemical cycles. Level 2 health threats, including pollution exposure and environmental health hazards, come next. Level 3 issues, particularly biodiversity conservation and the protection of human rights in environmentally vulnerable communities, form the third priority tier.

For businesses, the hierarchy challenges the comfortable narrative that corporate sustainability can be defined purely in terms of competitive advantage and stakeholder relations. Companies must assess whether their operations contribute to lower-level threats – not just whether they meet existing environmental regulations or satisfy ESG reporting frameworks. This requires moving beyond eco-efficiency metrics to measure actual impacts on ecosystem functions, species populations, and the livelihoods of communities at the frontline of environmental change.

For individuals and communities, the hierarchy provides a useful lens for evaluating sustainability claims. When a product is marketed as “sustainable,” it is worth asking: sustainable at which level? Does it address fundamental ecological threats, or does it simply align with consumer preferences for greener alternatives? Understanding the hierarchy helps distinguish between actions that protect the planet’s life-support systems and those that merely make us feel better about our consumption habits.

What do you think? Should corporate sustainability definitions be required to address the lower, more urgent levels of the sustainability hierarchy before claiming progress? And in your own life, how often do the sustainability choices you encounter address survival-level ecological threats versus quality-of-life preferences?

References

1. https://pubmed.ncbi.nlm.nih.gov/15757326/
2. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)02350-X/fulltext
3. https://www.worldwildlife.org/stories/what-is-the-sixth-mass-extinction-and-what-can-we-do-about-it
4. https://news.un.org/en/story/2024/05/1150056
5. https://en.wikipedia.org/wiki/Corporate_sustainability
6. https://www.researchgate.net/publication/256033203_Planetary_Boundaries_Ecological_Foundations_for_Corporate_Sustainability
7. https://journals.sagepub.com/doi/abs/10.1177/1086026617717456
8. https://www.arcticwwf.org/newsroom/news/wwf-living-planet-report-2024-a-planet-in-crisis/