Ecological Overshoot

According to data from the Global Footprint Network, humanity have been exceeding the capacity of Earth to regenerate since the 1970’s. This is a phenomenon known as ecological overshoot. In 2018 it was estimated that we were using a biocapacity equivalent to about 1.7 Earth’s. The Wikipedia entry for biocapacity contains this statement as at February 2023:

For example, there were roughly 12.2 billion hectares of biologically productive land and water areas on this planet in 2016. Dividing by the number of people alive in that year, 7.4 billion, gives a biocapacity for the Earth of 1.6 global hectares per person. These 1.6 global hectares include the areas for wild species that compete with people for space.

To achieve sustainability we need biodiversity to thrive. E. O. Wilson is famous for recommending that at least half Earth’s biocapacity is required for biodiversity to thrive. This means that the average biocapacity usage per capita in 2016 needed to be less than half the 1.6 global hectares that were available. So in 2016 the maximum biocapacity that was sustainably available was only 0.8 global hectares on average per person. The actual consumption in 2016 is irrelevant in this calculation, because we are just assessing the available biocapacity. Our actual usage was, and still is, well in excess of the available biocapacity. There are very few countries that are currently subsisting on less than 0.8 global hectares per capita; the global population is still rising; and Earth’s biocapacity is rapidly diminishing due to desertification, climate extremes, and biodiversity loss. These factors all combine to ensure that we can never reach sustainability unless we are willing to undertake an urgent campaign to willingly reduce our population size, as well as reducing our consumption to the minimum levels required to subsist and maintain our emotional resilience.

The UN Charter for Ecological Justice spells out the aspiration to voluntarily and equitably shrink our collective ecological footprint until we once again operate within the biocapacity of our planet. It uses scientific research which suggests that 2.14 global hectares per capita should be adequate for a human to achieve a fulfilled lifestyle. Note that if we achieved a global average consumption around this level the sustainable population is about 2.8 billion (6 billion gha / 2.14 gha). This only applies if Earth’s ecosystems can be restored to a healthy level of biodiversity. The chart below shows the current split between those above and below this consumption level.

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