Earth Overshoot Day, first created in 2006, aims to calculate the number of days per year that correspond to the necessary biocapacity — the ability of an ecosystem to reestablish its biological resources and absorb waste — to account for civilisation’s ecological footprint. Global Footprint Network (GFN), the research organisation which comes up with the yearly date along with environmental group WWF, compares the calculation to a bank statement tracking income against expenditures. It crunches thousands of UN data points on resources like biologically productive forests, grazing lands, cropland, fishing grounds and urban areas. That tally is then measured against the demand for those natural resources, among them plant-based foods, timber, livestock, fish and the capacity of forests to absorb carbon dioxide emissions. Today, humanity uses about 74% more than what global ecosystems can regenerate; to continue living the way we do now, we’d need the resources of about 1.7 Earths. And that doesn’t look set to change any time soon. CO2 emissions related to energy — particularly fossil fuels like coal — are projected to grow by 4.8% this year over 2020 levels, according to the International Energy Agency.