Earth Overshoot Day 2021: what the date represents and how it was estimated
Earth Overshoot Day marks the date when humanity's demand for ecological resources and services exceeds what the planet's ecosystems can regenerate in that year. In 2021, the Global Footprint Network announced the date as 29 July.
The Ecological Footprint estimates the biologically productive area needed to provide the resources people consume and absorb certain wastes, including carbon dioxide. Biocapacity represents ecosystems' ability to regenerate those resources and absorb waste. The date is calculated by dividing global biocapacity by humanity's Ecological Footprint and multiplying the result by the number of days in the year.
The annual date is not a real-time measurement. National accounts rely on international statistics published with a time lag. To estimate the current year, the Global Footprint Network extends trends and incorporates more recent data where available. The result is an estimate that may be revised as historical datasets are updated.
The 2021 estimate highlighted a 6.6% increase in the carbon Footprint compared with 2020 and an estimated 0.5% decrease in global forest biocapacity, associated in part with degradation and deforestation in the Amazon. The comparison with 2020 should also be understood in the context of the temporary reduction in economic activity during the pandemic.
The indicator communicates humanity's aggregate pressure on the planet's regenerative capacity. It does not mean that all resources run out on a single date, and it does not replace specific indicators for water, biodiversity, climate or land use. LCA provides a complementary analysis of impacts associated with products, services and supply chains.
References
- Global Footprint Network — 2021 calculation
- How Earth Overshoot Day is calculated
- 2021 nowcast report