Earth Overshoot Day (Thursday August 13th, 2015), marks the date when humanity’s demand for ecological resources and services in a given year exceeds what Earth can regenerate in that year. We maintain this deficit by liquidating stocks of ecological resources and accumulating waste, primarily carbon dioxide in the atmosphere. Earth Overshoot Day is hosted and calculated by Global Footprint Network, an international think tank that coordinates research, develops methodological standards and provides decision-makers with a menu of tools to help the human economy operate within Earth’s ecological limits.

To determine the date of Earth Overshoot Day for each year, Global Footprint Network calculates the number of days of that year that Earth’s biocapacity suffices to provide for humanity’s Ecological Footprint. The remainder of the year corresponds to global overshoot. Earth Overshoot Day is computed by dividing the planet’s biocapacity (the amount of ecological resources Earth is able to generate that year), by humanity’s Ecological Footprint (humanity’s demand for that year), and multiplying by 365, the number of days in 2015:

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

Measuring Ecological Wealth

Just as a bank statement tracks income against expenditures, Global Footprint Network measures a population’s demand for and ecosystems’ supply of resources and services. These calculations then serve as the foundation for calculating Earth Overshoot Day.

On the supply side, a city, state, or nation’s biocapacityrepresents its biologically productive land and sea area, including forest lands, grazing lands, cropland, fishing grounds, and built-up land.

On the demand side, the Ecological Footprintmeasures a population’s demand for plant-based food and fiber products, livestock and fish products, timber and other forest products, space for urban infrastructure, and forest to absorb its carbon dioxide emissions from fossil fuels.

Both measures are expressed in global hectares—globally comparable, standardized hectares with world average productivity. A hectare is equivalent to 10,000 square meters or 2.47 acres

Each city, state or nation’s Ecological Footprint can be compared to its biocapacity. If a population’s demand for ecological assets exceeds the supply, that region runs an ecological deficit. A region in ecological deficit meets demand by importing, liquidating its own ecological assets (such as overfishing), and/or emitting carbon dioxide into the atmosphere.

At the global level, ecological deficit and overshoot are the same, since there is no net import of resources to the planet.


The concept of Earth Overshoot Day was first conceived by Andrew Simms of the UK think tank New Economics Foundation, which partnered with Global Footprint Network in 2006 to launch the first global Earth Overshoot Day campaign. At that time, Earth Overshoot Day fell in October. WWF, the world’s largest conservation organization, has participated in Earth Overshoot Day since 2007.  


Here are some suggested steps that you can take to help end Earth Overshoot.


Join AELA’s “Let’s Talk About Consumption” workshop and publications series and complete the national survey that invites all Australians to share information about the initiatives and projects they’re working on, to reduce consumption and live within their ecological limits.

Use the power of art as a catalyst for public awareness and environmental change.

Blue Ventures works to rebuild tropical fisheries with coastal communities on the front line of many challenges including climate change and over consumption of limited resources. Take action to support our cross sectoral work in marine conservation or volunteer in Madagascar or Belize to see a very different side of life for yourself.

Join the Center for Biological Diversity in demanding that Target meet their own sustainability goals by eliminating single-use plastic shopping bags from all stores in the United States.


CARE’s response to climate change is rapidly growing to reflect the scope and severity of the challenge. Our overarching objectives are to empower poor and marginalised people to take action on climate change at all levels and to build knowledge for global change. See the climate reality of the communities we partner with and the work we do


Sign a climate petition that will be delivered at COP21 to world leaders to show the power of the environmental movement and the desire to move to 100% renewable energy.


Fledge welcomes volunteers and scholars to submit innovative ideas to increase action at the individual and community levels in India to reduce their National Ecological Footprint. The three best ideas will receive a commemorative certificate and a citation. Please write to


Support Plattform Footprint to convince the Austrian Government to pledge binding reductions for ecological footprint and CO2 emissions beyond 2020 and to start implementing the necessary measures immediately!

Learn more about how each minute, forest area the size of five soccer fields is illegally cleared to line our supermarket shelves with bread, cookies, margarine, and other consumer products.


Measure your personal Ecological Footprint with our online calculator (desktop only) and learn what you can do to reduce it. Sign up for our newsletter to stay up to date on the latest news about the Ecological Footprint.


Join Global Population Speak Out and help raise awareness by distributing copies of our book Overdevelopment, Overpopulation, Overshoot.


Apply for or partner on the Transformative Actions Program (TAP) and help cities and regions TAP their potential for action on climate change.


Ecuador is the only country in Latin America to calculate its National Footprint with official data and include this indicator within its development plan “National Plan for Good Living.” Discover how you can help reduce your Ecological Footprint through simple actions with “You can make the difference / A greener world depends on us.


Learn about and teach sustainability with short and engaging animation videos.

Be responsible in your choice of packaging by looking for packaging material made from renewable resources.


Cut C02 emissions by walking, cycling or using public transport instead of the car or motorbike. Discover 365 different individual actions on our “Biodiversity is Us” application for smartphones and tablets.


Seize the biggest business opportunity for the foreseeable future, the transition to a low carbon economy. Join our Low Carbon Technology Partnerships initiative (LCTPi) and collaborate across industries to be part of the climate solution


Sign WWF’s letter to President Obama and tell him you support the Clean Power Plan and his recent efforts to address climate change.


WWF China:Calculate your personal footprint to learn how many Earths would be required to sustain your lifestyle. Participate in the sustainable consumption week, a campaign involving more than 600 stores in China August 4 to 18 that calls for more sustainable consumption to help reverse overshoot.