As inhabitants of planet Earth we use up more natural resources in a given year than nature can absorb or replenish. In the past, when the global population was significantly lower, we were able to live ‘sustainably’. But during the mid-1970s, with the global population reaching 4 billion - roughly half of what it is today - we crossed a threshold. The demand we started placing on nature exceeded what nature could regenerate in that year. Earth Overshoot Day was born. On that day we ran out of budget and used up all resources nature should have had for us for the remainder of the year.