Measuring Sustainability: Indicators for Tracking Progress

How do you know whether a country, a city, or even the entire planet is actually moving toward sustainability? You cannot manage what you cannot measure – and that is exactly where sustainability indicators come in. These quantifiable metrics help governments, organizations, and researchers track progress, identify gaps, and make informed decisions about environmental, social, and economic policies. Without them, sustainable development would remain an abstract ideal rather than a measurable goal.

The role of indicators in sustainable development 🔗

Sustainability indicators are specific, measurable data points that provide a snapshot of how well a system – whether a nation, region, or organization – is performing against sustainability objectives. They translate broad goals like “end poverty” or “protect biodiversity” into concrete, trackable metrics such as the proportion of the population below the poverty line or the rate of forest loss per year.

For policymakers, these indicators serve multiple functions. They help set baselines to understand the current state of affairs, track trends over time, compare performance across regions, and evaluate whether specific policies are working. The UN Statistics Division maintains the global indicator framework specifically because decision-makers need standardized data to coordinate international action on sustainable development.

Indicators also play a critical role in accountability. When countries commit to targets – such as those under the 2030 Agenda for Sustainable Development – indicators provide the evidence base for assessing whether those commitments are being met. National and local governments use them to prepare voluntary national reviews, which they submit to the United Nations to report their progress.

Beyond government use, sustainability indicators help businesses evaluate their environmental footprint, allow civil society organizations to hold institutions accountable, and give researchers a common language for studying development patterns across different contexts.

Weak vs. strong sustainability indicators 🔗

Not all sustainability indicators are built on the same assumptions. The debate between weak sustainability and strong sustainability represents a fundamental divide in how we conceptualize – and therefore measure – sustainable development.

Weak sustainability indicators 🔗

Weak sustainability operates on a key assumption: that different types of capital – natural, manufactured, human, and social – are interchangeable. Under this view, depleting a natural resource is acceptable as long as you compensate by building up manufactured or human capital of equivalent value. For instance, cutting down a forest is considered sustainable if the economic gains from logging are reinvested into infrastructure or education.

Indicators built on this framework tend to be economic in nature. Genuine Savings (also called Adjusted Net Savings) is a prominent example – it measures whether a country is saving enough to offset the depletion of its natural resources and environmental degradation. Green GDP is another concept in this category, adjusting traditional GDP figures to account for resource depletion and pollution costs. However, adoption of green GDP has been slow due to the technical difficulty of putting a price tag on nature.

The Genuine Progress Indicator (GPI) and the Index of Sustainable Economic Welfare (ISEW) also fall under this umbrella. They attempt to adjust economic output measures by factoring in environmental and social costs that standard GDP ignores.

The core criticism of weak sustainability indicators? They rely on an unrealistic assumption of substitutability between natural and manufactured capital. You cannot replace a collapsed ecosystem or an extinct species with a factory or a road, no matter how economically productive that factory might be.

Strong sustainability indicators 🔗

Strong sustainability takes the opposite position: certain ecological functions and resources cannot be substituted with technological or manufactured replacements. Natural capital has unique, irreplaceable qualities – clean air, stable climate systems, pollination services, fertile soil – that human-made capital simply cannot replicate.

Indicators based on strong sustainability therefore focus on physical and ecological measures rather than monetary ones. The Ecological Footprint is a leading example. Developed by the Global Footprint Network, it measures how much biologically productive land and water area a population requires to produce the resources it consumes and absorb its waste. This demand is then compared against the Earth’s available biocapacity. If demand exceeds supply, the population is in ecological overshoot.

Other strong sustainability indicators include material flow analysis, which tracks the total physical throughput of materials in an economy, and planetary boundary indicators, which measure how close human activity is to crossing critical ecological thresholds like climate change, biodiversity loss, and nitrogen cycle disruption.

The key strength of strong sustainability indicators is that they respect ecological limits. Their limitation, however, is that physical data can be harder to collect and standardize across countries compared to economic data.

Examples of sustainability indicators in action 🔗

The most ambitious application of sustainability indicators at the global scale is the United Nations Sustainable Development Goals (SDGs) framework.

The UN SDG indicator framework 🔗

When 193 UN member states adopted the 2030 Agenda for Sustainable Development in 2015, they committed to 17 goals and 169 targets spanning poverty, hunger, health, education, gender equality, clean water, energy, economic growth, inequality, climate action, and more. To track progress on these targets, the Inter-Agency and Expert Group on SDG Indicators (IAEG-SDGs) developed a global indicator framework.

As of 2025, this framework includes 234 unique indicators covering environmental, social, and economic dimensions. Each goal has eight to twelve targets, and each target has between one and four indicators. These indicators measure specific changes – proportions, rates, amounts – that signal whether progress is being made.

The indicators are classified into tiers based on data availability. As of late 2024, 161 of the 231 unique indicators at the time were classified as Tier I (meaning they have an established methodology and regular data production), while 62 remained Tier II (methodology exists but data is not regularly produced). This tiering system is important because it reveals where data gaps still exist.

The SDG indicator framework underwent its second and final comprehensive review in 2025, during which proposals were considered for replacing, revising, and adding new indicators to strengthen the monitoring process for the remaining years of the 2030 Agenda.

Human Development Index (HDI) 🔗

The HDI, developed by the United Nations Development Programme, measures a country’s average achievements across three dimensions: health (life expectancy at birth), education (mean and expected years of schooling), and standard of living (gross national income per capita). It was introduced in 1990 as an alternative to purely economic measures of development.

While the HDI is widely used and effective at capturing human well-being, it has a significant blind spot: it does not account for environmental sustainability. A country can score very high on the HDI while consuming resources at a rate that would require multiple planets if everyone lived that way.

Ecological Footprint paired with HDI 🔗

To address this gap, researchers have combined the Ecological Footprint with the HDI to create a more holistic picture. The Global Footprint Network uses this pairing to identify which countries are achieving high human development within the planet’s ecological limits. The UN considers an HDI above 0.8 as “very high” human development, while a sustainable Ecological Footprint requires staying below the global average biocapacity of approximately 1.5 global hectares per person.

The sobering finding? Very few countries achieve both. Most high-HDI countries have ecological footprints far exceeding what the planet can sustain. This reveals a fundamental tension: development as conventionally pursued tends to come at the expense of environmental sustainability.

Other notable indicators 🔗

Several other indicators are used globally to assess sustainability from different angles:

Environmental Performance Index (EPI) – Developed by Yale and Columbia universities, this index ranks countries on environmental health and ecosystem vitality using dozens of indicators covering air quality, water sanitation, biodiversity, and climate policy.

Genuine Progress Indicator (GPI) – This adjusts GDP by subtracting costs like pollution damage, loss of leisure time, and income inequality while adding the value of household work and volunteer activities.

Happy Planet Index (HPI) – This measures how efficiently countries deliver long, happy lives relative to their ecological resource use. Costa Rica consistently ranks highly on this index despite having a fraction of the GDP per capita of countries like the United States.

Sustainable Development Index (SDI) – Proposed as a strong sustainability alternative to the HDI, it retains the base formula of the HDI but divides it by per capita CO₂ emissions and material footprint, measured against planetary boundaries. This makes it a measure of ecological efficiency in delivering human development.

The need for integrated indicators 🔗

One of the biggest challenges in sustainability measurement is that environmental, social, and economic dimensions are deeply interconnected – but most indicators only capture one dimension at a time. GDP tells you about economic output but nothing about biodiversity. The Ecological Footprint tells you about resource consumption but does not capture income inequality or educational access.

Why single-dimension indicators fall short 🔗

Sustainability is inherently multidimensional. Climate change affects food production, which affects poverty, which affects political stability. Water scarcity impacts public health, economic productivity, and ecosystem functioning simultaneously. When indicators only measure one aspect, they can paint a misleading picture. A country can look sustainable on one metric while being deeply unsustainable on another.

This problem is evident even within the SDG framework. While it covers 17 goals across multiple dimensions, some scholars argue that the SDGs are internally incoherent, with certain targets conflicting with each other. For example, pursuing aggressive economic growth (Goal 8) can undermine environmental targets (Goals 13, 14, and 15) if growth relies on increased resource extraction and emissions.

Moving toward composite and integrated measures 🔗

To address these limitations, researchers have worked on developing composite indicators that combine multiple dimensions into a single index. The SDI, the Doughnut Economics framework proposed by Kate Raworth, and the HDI-Footprint pairing are all attempts at this kind of integration.

Raworth’s Doughnut framework is particularly notable. It visualizes sustainability as a space between two boundaries – a social foundation (the minimum level of well-being no one should fall below) and an ecological ceiling (the planetary limits no one should exceed). The goal is to operate in the space between these two boundaries. This framework has gained traction at city and regional levels, with places like Amsterdam and Barcelona using it to guide local policy decisions.

Another important direction is dashboard approaches, where instead of trying to collapse everything into a single number, policymakers track a curated set of indicators side by side. The SDG framework itself functions this way at a macro level, and national statistical offices often create their own dashboards tailored to local priorities.

Data challenges and the path forward 🔗

Developing better integrated indicators also depends on improving data infrastructure. Many countries, particularly in the Global South, lack the statistical capacity to produce reliable data across all sustainability dimensions. The SDG Report 2025 acknowledges that while substantial development gains have been made since 2015, progress remains uneven and the current pace is insufficient to achieve all goals by 2030.

Investments in national statistical systems, remote sensing technology, and open-data platforms are all helping close these gaps. The UN’s Data Commons for SDGs, for example, leverages AI and machine learning to make key sustainability data more accessible to policymakers, researchers, and the public.

Ultimately, the goal is not to find a single perfect indicator – that may not be possible given the complexity of sustainability. Instead, the focus should be on developing indicator frameworks that are transparent about their assumptions (weak vs. strong sustainability), comprehensive enough to capture multiple dimensions, and practical enough to guide real policy decisions.

What do you think? Should governments prioritize strong sustainability indicators that respect ecological limits, even if they are harder to measure? And can any set of indicators truly capture the full complexity of sustainable development, or will there always be critical blind spots?

References

1. https://unstats.un.org/sdgs/indicators/indicators-list/
2. https://en.wikipedia.org/wiki/Sustainable_Development_Goals
3. https://en.wikipedia.org/wiki/Sustainability_metrics_and_indices
4. https://www.emerald.com/insight/content/doi/10.1108/09566169910275022/full/html
5. https://www.sciencedirect.com/science/article/abs/pii/S092180090600454X
6. https://www.footprintnetwork.org/our-work/sustainable-development/
7. https://unstats.un.org/sdgs/iaeg-sdgs/2025-comprehensive-review
8. https://sdg.iisd.org/news/iaeg-sdgs-updates-on-2025-review-of-global-indicator-framework/
9. https://www.sciencedirect.com/science/article/abs/pii/S0921800919303386
10. https://unstats.un.org/sdgs/report/2025/