When humanity’s demand for natural resources and services in a given year exceeds what the Earth can renew in that year, Earth Overshoot Day occurs. We keep this deficit going by depleting natural resource supplies and accumulating trash, principally carbon dioxide, in the atmosphere. Global Footprint Network, a worldwide research organisation that offers decision-makers a menu of tools to assist the human economy in operating within Earth’s ecological constraints, hosts and calculates Earth Overshoot Day.

The Global Footprint Network determines the number of days in each year when Earth’s biocapacity is sufficient to meet humanity’s Ecological Footprint to determine the date of Earth Overshoot Day. The rest of the year is characterised by a global overshoot. The Earth Overshoot Day is calculated by multiplying the planet’s biocapacity (the quantity of ecological resources Earth can generate in a given year) by humanity’s Ecological Footprint (humanity’s demand for that year) by 365:

(Earth’s Biocapacity / Humanity’s Ecological Footprint) x 365 = Earth Overshoot Day

Measuring Ecological Wealth

Global Footprint Network assesses a population’s demand for and ecosystems’ supply of resources and services, similar to how a bank statement tracks revenue and expenditures. The results of these calculations are then used to calculate Earth Overshoot Day.

On the supply side, biocapacity refers to the biologically productive land and sea area of a city, state, or nation, including forest lands, grazing lands, agriculture, fishing grounds, and built-up land.

Global Footprint Network assesses a population’s demand for and ecosystems’ supply of resources and services, similar to how a bank statement tracks revenue and expenditures. The results of these calculations are then used to calculate Earth Overshoot Day.

On the supply side, biocapacity refers to the biologically productive land and sea area of a city, state, or nation, including forest lands, grazing lands, agriculture, fishing grounds, and built-up land.

The Ecological Footprint assesses a population’s need for plant-based food and fibre goods, animal and fish products, lumber and other forest products, urban infrastructure space, and forest to absorb carbon dioxide emissions from fossil fuels on the demand side.

 Both are expressed in global hectares, which are standardised, globally similar hectares with average world productivity. A hectare is 10,000 square metres (2.47 acres) in size.

The Ecological Footprint of each city, state, or country can be compared to its biocapacity. When the demand for natural assets outnumbers the supply, the region suffers from an ecological deficit. A territory with an environmental deficit must import, liquidate its own ecological assets (such as overfishing), and emit carbon dioxide into the atmosphere to meet demand.

Because there is no net resource input globally, ecological deficit and overshoot are the same at the global level.

Methodology and Projections

Earth Overshoot Day is a hunch rather than a precise date. It’s impossible to predict when we’ll blow our ecological budget with 100% certainty. Therefore, revisions to the date we enter overshoot are due to improved estimates, not human-environmental advancements.

Projections will continue to modify as the methodology of the Global Footprint Network evolves. However, every scientific model used to account for human demand and nature’s supply shows the same pattern: we’re way over budget, and debt is mounting. It’s an ecological debt, and the interest we’re paying on it—food shortages, land degradation, and CO2 buildup in our atmosphere—has severe human and financial consequences.

History of earth overshoot day

Andrew Simms of the UK created earth Overshoot Day think tank New Economics Foundation, which partnered with Global Footprint Network to launch the first global Earth Overshoot Day campaign in 2006. We’ve gone much over budget, and the debt is growing. It’s an ecological debt, and the interest we’re paying on it—food shortages, land degradation, and CO2 buildup in our atmosphere—has severe human and financial consequences.

What can we do?

Small actions can have a significant impact. Consider altering your consumption habits and encouraging others to do so as well. 

Reduce your carbon footprint:

Avoid driving REC-Individual-1 and offset your emissions with carbon offsets. Instead, use your bike or short walks to get around.

Conserve energy and encourage the use of renewables. Unplug your electrical vampires and set your thermostat to a higher temperature in the summer and a lower temperature in the winter. Consider getting solar panels installed. Support renewable energy with our Renewable Energy Credits if you haven’t already. We reduce the need to use fossil fuels for years to come by developing a future with more renewable energy.

Consume a vegetarian diet that is low in carbon.

Purchase environmentally friendly things. Buying sustainably is growing easier by the day.

Reduce your water footprint:

Stop leaks and turn off the faucet when not in use. Leaks waste 10 gallons of water every day on average. You can save 14% on your indoor water use by plugging up.

When shopping for appliances, look for the EnergyStar and WaterSense labels. They were created to conserve water.

Grow a garden that requires less water. Numerous lawn choices will make you wonder why you spent so much time mowing! Collect rainwater and greywater. With fewer gallons, you’ll be able to accomplish more. Collect water for plants while you wait for the tap to warm up, for example.

BEF Water Restoration Certificates help you reduce your water footprint.