A country’s overshoot day is the date on which Earth Overshoot Day would fall if all of humanity consumed like the people in that country.
Country overshoot days are published on January 1st of each year. In order to meet this publication deadline, the 2023 country overshoot days were calculated in December 2022 using the 2022 edition of the National Footprint and Biocapacity Accounts, which was the latest edition available at the time. The 2022 edition data stretches from 1961 to 2018. This is due to a three to four-year lag between the latest data-year and the latest edition year as a result of the UN’s reporting process. Additionally, time is needed to assemble the accounts.
Let’s take Swiss Overshoot Day as an example. Its 2023 overshoot day is based on the latest (2018) available results from the 2022 edition of the National Footprint and Biocapacity Accounts:
- The Ecological Footprint of Switzerland is 4.35 global hectares (gha) per person (in 2018)
- Global biocapacity is 1.6 gha per person (in 2018)
Therefore, it would take (4.35/ 1.6) = 2.75 Earths to support humanity if everyone on the planet lived like the Swiss.
We can determine Swiss Overshoot Day using the equation 365 x (1.6/4.35) = 133, or as the 133rd day in the year. The 133rd day of 2023 is May 13th.
Not all countries will have an overshoot day. By way of the country overshoot equation above, a country will only have an overshoot day if its Ecological Footprint per person is greater than global biocapacity per person (1.6 gha). Countries with an Ecological Footprint per person that is less than global biocapacity per person (1.6 gha) and which do not have an overshoot day are listed as “none” in this table. In leap years, we calculate the date based on a 366 day-long year, rather than the usual 365.
IMPACT OF COVID-19 AND THE INVASION OF UKRAINE
Many have asked us about the war in Ukraine and the coronavirus pandemic’s impact on each country’s Ecological Footprint and overshoot day. Because of time delays in UN statistics, the latest full assessment of countries only stretches through 2018 and does not cover these events. Producing country estimates for 2023 is possible, as explained in the box on the right.
HOW EARTH OVERSHOOT DAY IS CALCULATED
To address the “gap” between the latest data-year and the present, Global Footprint Network uses additional UN statistics and trendlines from the National Footprint and Biocapacity Accounts to extend the global results all the way to the present year. Read more about how Earth Overshoot Day 2022 was calculated. Our assessment for Earth Overshoot Day 2023 will be released on June 5, 2023.
Now-Casting Country Footprints
Estimating today’s Ecological Footprint of a country, which is called “now-casting,” can be useful for policy analysts and decision-makers. This is done by integrating the more recent UN data and applying updated data points from other sources. Now-casts can provide a business-as-usual estimate based on a combination of historic trends and recent data, but are not biophysical accounts based on reported data, and therefore must be treated with the same caution as a forecasting model. We undertake projects for which this approach is appropriate through partnerships, as we did for WWF France in 2022. Please reach out to us if you are interested in commissioning such an analysis. Typically, the assessment takes a few weeks.