We are using 50 percent more resources than the Earth can sustainably produce, and unless we change course not even two planets will be enough to sustain mankind.

This is the message from Morne du Plessis, chief executive of WWF-SA, on Earth Overshoot Day.

This is the day of the year when people have used as much renewable natural resources as our planet can regenerate in one year.

The day was initiated by the Global Footprint Network, which uses ecological footprint data to measure what resources we have, who uses them, and to what extent. Global Footprint Network’s data shows that Africa’s ecological footprint is expected to double by 2040 and that the continent’s resource demand will outstrip domestic availability by 2015.

Du Plessis said: “If everyone in the world consumed at South Africa’s rate, then we would need 2.2 planets to sustain ourselves. We are asking for more than we have available, and we are not alone. Today, more than 80 percent of the world’s population lives in countries that use more than their own ecosystems can renew.”

Overshoot Day illustrates that from tomorrow we are effectively in overdraft on the balance sheet of nature’s goods and services.

Egypt’s residents consume the ecological resources of 2.4 Egypts. Kenya uses the ecological resources of 1.8 Kenyas.

Du Plessis said switching to clean, renewable, abundant energy sources like solar energy and wind power would slash dirty emissions that strained our oceans and natural vegetation, and polluted our air.

Jim Leape, director-general of WWF International said: “More than 50 percent of humanity’s ecological footprint is composed of our carbon footprint, especially from the burning of fossil fuels.”

The WWF is running a global campaign, Seize Your Power, pressing for much greater investment in renewable energies, saying that “for a clean and healthy future for our children, we must preserve the natural capital that is left – and be much better stewards of the planet we call home”.