August 20, 2013, Kyiv — The Ecological Debt Day, also known as Earth Overshoot Day, in 2013 fell on August 20. This means that as of this date, according to approximate calculations, the humanity "by a joint effort" has exhausted the planet's annual biological capacity to renew its natural resources, absorb man-made wastes, and sequestrate greenhouse gases. From this day on until the end of the year, we will live with an "overdraft" – further draining the stock accumulated by nature all over its history and accumulating carbon dioxide in the atmosphere.

The coming of Earth Overshoot Day is calculated from the ratio of the Earth's annual biocapacity to so-called "Ecological Footprint" in that year, which is the global consumption of natural resources and CO₂ sequestration:

Earth Overshoot Day = [World Biocapacity]/[World Ecological Footprint] х 365

The Overshoot Day has a sad trend of creeping ever closer to the beginning of year. Before 1987, the humanity managed to keep within the Earth's biocapacity. In 1987, however, the annual "budget" of natural resources was first spent up ahead of schedule – by December 19. Last year, the Day fell on August 22.

According to Global Footprint Network (GFN), which conducts Earth Overshoot Day campaigns every year, to meet our today's demand for renewable ecological resources we would need to have one and a half Earths. If we don't change our attitude toward resources, we will need two Earths well before the mid-21st century.

Not in all countries the demand for resources exceeds the capacity of their ecosystems. As examples, GFN cites Australia, Brazil, Canada, Sweden, Madagascar and Indonesia, where Ecological Footprint is below biocapacity. However, the spread between the two in these countries is narrowing by the year.

In Ukraine, one year after gaining independence in 1991, its Ecological Footprint level was almost twice that of biocapacity. Until 1999, the Ecological Footprint was plummeting, obviously as a result of the economic decline, and has been gradually increasing since then. As of 2007, the volume of natural resources consumption in Ukraine exceeds the replenishing capacity of its ecosystem by a factor of 1.6. At the same time, Ukraine is one of few European "biocapacity exporters" – along with Finland, Norway, Russia and Sweden – that have a positive balance of their exports' and imports' Ecological Footprints (2007).

The worst ratio of Ecological Footprint to biocapacity is in Japan, which consumes natural resources at seven times what its nature is able to reproduce.

The concept of Earth Overshoot Day was developed by Andrew Simms of UK think tank New Economics Foundation, a GFN partner.