Introducing SEDI: Measuring the Seasonal Ecological Debt of Tourism Destinations

“You cannot improve what you do not measure.” That principle has guided sustainability for decades. Yet one important question has often remained unanswered:

Many tourism destinations appear sustainable when viewed across an entire year. Annual statistics smooth out the peaks and present averages that can hide what residents, ecosystems and public infrastructure experience during the tourism season.

A small coastal city may have enough water, transport capacity and waste management infrastructure for most of the year. During July and August, however, visitor numbers may multiply several times over. Roads become congested, water demand rises, waste generation accelerates and protected natural areas receive far more visitors than they were originally designed to accommodate.

This is the challenge that inspired the development of the Seasonal Ecological Debt Index (SEDI).

SEDI was created by Green Path Alliance to measure the seasonal environmental, social and governance pressures generated by tourism. Rather than evaluating policies or commitments alone, SEDI focuses on the measurable effects that tourism places on destinations during periods of highest demand.

Why Seasonal Ecological Debt?

Tourism creates economic opportunities, employment and cultural exchange. It also places additional pressure on local communities and ecosystems.

The purpose of SEDI is not to discourage tourism.

Its purpose is to understand:

• when pressures occur
• where they occur
• why they occur
• and how destinations can manage them more effectively

The concept of Seasonal Ecological Debt describes the temporary environmental and social burden created when tourism demand exceeds the normal operating conditions of a destination.

Examples include:

• increased freshwater consumption
• higher waste generation
• seasonal traffic congestion
• air quality deterioration
• visitor pressure on sensitive ecosystems
• seasonal labour dependency
• pressure on local housing
• growing infrastructure demands

By measuring these pressures systematically, destinations can prioritise investments, improve planning and communicate their progress transparently.

A Different Perspective on Sustainability

Many sustainability frameworks evaluate whether policies, strategies or commitments exist.

SEDI asks an additional question:

Instead of relying on declarations alone, the methodology combines measurable indicators with transparent evidence. Every indicator is assessed using documented sources and classified according to its level of confidence.

The Six Dimensions of SEDI

The methodology evaluates destinations across six complementary dimensions.

Transparency Before Perfection

One of the principles behind SEDI is simple:

Not every destination publishes every dataset required for a comprehensive assessment.

Rather than hiding these gaps, SEDI makes them visible.

Every indicator is clearly classified as:

This allows readers to understand not only the score itself but also the confidence behind it.

Drivers of Ecological Debt

A single score rarely explains why a destination performs well or poorly.

SEDI therefore identifies the Drivers of Ecological Debt.

These drivers highlight the indicators that contribute most significantly to seasonal environmental and social pressure.

Instead of asking:

Decision-makers can ask:

This transforms SEDI from a reporting tool into a practical management framework.

Designed for Continuous Improvement

SEDI has not been designed as a one-time assessment.

Destinations can repeat the assessment annually, allowing them to monitor progress, compare results over time and evaluate the effectiveness of policy interventions.

As more official datasets become available, confidence increases while maintaining methodological transparency.

The First Pilot

Every methodology begins with a first application.

The inaugural SEDI Pilot Assessment has been conducted for Split, Croatia, where the framework was tested using publicly available official statistics, environmental datasets and transparent proxy methodologies where necessary.

The pilot helped validate:

• the indicator structure
• evidence classification
• confidence assessment
• reporting methodology
• and practical usability

It also generated valuable improvements that will be incorporated into future versions of the framework.

Looking Ahead

Sustainable tourism is no longer only about reducing impacts.

It is about understanding them.

By combining environmental science, tourism statistics, governance transparency and destination management into a single framework, SEDI aims to support better decisions rather than simply produce another sustainability score.

As more destinations participate, each assessment contributes to a growing body of knowledge that helps governments, tourism organisations and local communities better understand the seasonal pressures they experience — and the opportunities they have to manage them.

The journey begins with measurement.

Because every sustainable destination starts with one simple question: