Ecological overshoot keeps growing. As a result, humanity is facing a ballooning ecological debt. Since our planet cannot be depleted forever, overshoot will eventually end. The question is whether this will happen by design or disaster.

So, how do we design our future? The beta version of this simple tool allows you to design possible futures by choosing key parameters that shape overshoot: how much biocapacity we will lose or gain over time, how much each of us will use, and how many of us there will be on the planet. You can also choose how quickly the change in consumption and family size may happen. What do your explorations reveal?

Data sources include the National Footprint and Biocapacity Accounts, the UN Population Programme, and the World Bank. The full population model powering the scenario tool’s population projections is available here.

The purpose of this tool is to explore a range of outcomes humanity could generate. Play with the levers to shift the trajectories.

Overshoot is determined by the “supply side” (biocapacity: how much is being regenerated), and on the “demand side” (footprint: how much is being taken). The demand can then be broken down into how much is being taken per person, and how many people there are.

Your assumptions about how these parameters will change enable this tool to calculate the implications for overshoot. Therefore, you can both explore what might be likely futures, as you choose parameters according to what you believe is probable. You can also test options, by exploring how parameters would have to change to achieve particular overshoot outcomes.

Ecological debt: most ecological impact is driven by the accumulation of overshoot over time. Overshoot’s 50-year persistence has led to a massive ecological debt. It would take Earth 20.5 years to regenerate what was depleted, if we left Earth untouched. Also, this ecological debt may not be fully reversible. The number on the bottom of the scenario tool shows you how much ecological debt will have accrued by the end of the century (in Earth-years). Like with money, the ecological debt is the sum of the yearly deficits.  A big portion of the debt is the build-up of greenhouse gases in the atmosphere. 

The current ecological debt of 20.5 Earth-years is high, and it is not clear how much more ecological debt the biosphere can absorb without regeneration starting to decline. The ability of the biosphere to regenerate is challenged by pressures like soil erosion, freshwater shortage, climate change, or biodiversity loss. The future ability of the biosphere to regenerate is the third parameter you can choose in this scenario tool). 

The population scenarios are calculated with our cohort model available for download here (2021 version). To explore variances in per person footprints, you can use our personal Footprint calculator.

Default parameters:

• Ecological footprint: Humanity’s Ecological Footprint is approximately 2.77 global hectares per person. Learn more about Ecological Footprint here. For more information about Footprint over time, check here.
• Fertility rate: The global average fertility rate in 2020 was about 2.35 children born per woman over her lifetime. It has been declining.
• Age of mother at birth of first child varies among countries, from 18 years in Chad to 31 years in Switzerland, Italy, Spain, South Korea or Japan.
• Biocapacity: Based on FAO statistics, the planet’s biocapacity has increased on average 0.46% annually since 1961, largely driven by agricultural intensification. But this number may hide ecological damages that undermine future yields.

The future of this tool: With additional resources, Global Footprint Network plans to expand upon this beta version to make the tool more versatile. For example, we will break down population side and the consumption side into more parameters. For instance, consumption could be split into different categories, so one could choose how much we will reduce carbon emissions and how much of that reduction will truly vanish. This is because some of the carbon reduction could simply shift pressure onto other Footprint categories such as when biofuels are used rather than fossil fuels, or when cotton replaces synthetic fibers). You could also be able to choose how much humanity reduces its biological resource use, for instance, by using less animal-based food, or by using biological materials longer. We would also love to add more specific choices for strengthening (or weakening) our planet’s biocapacity.

The population side is complex, because family size is influenced indirectly: as women and men start to have equal rights and opportunities, family sizes shrink, markedly. Also, access to reproductive health reduces family size and leads to longer and healthier lives for all family members. In contrast, imposed family policies typically backfire: their effectiveness is minimal, and they cast long shadows of psychological and cultural wounds.

Additional Resources
• Check out Ecological Footprint and biocapacity data for countries from 1961 to today
• Learn about the factors that determine ecological overshoot. These are also the five key solution areas
• Calculate your personal Ecological Footprint
• Find out more about the population dimension
• Should we even talk about population?
• Download and play with a population cohort model Global Footprint Network assembled (2021 version). It allows to calculate implications of changes in fertility, mortality, and average age of mothers
• Explore existing solutions
• Add solutions you love to the #MoveTheDate map

We’d love to hear your feedback on the tool. Please email Mathis at mathis(at)footprintnetwork.org to share your comments or concerns.