Earth Overshoot Day returns to July 29

Earth Overshoot Day 2021 falls on July 29, Glasgow City Council Leader Susan Aitken announced on behalf of Global Footprint Network and the Scottish Environmental Protection Agency (SEPA).

“With still almost half a year ahead of us, by July 29, 2021 we have already exhausted all the biological resources that our planet’s ecosystems can renew over the course of the entire year. If we need a reminder that we’re in the grip of a climate and ecological emergency, Earth Overshoot Day helps us do that,” said the councilwoman.

The date is already back alongside 2019, after being momentarily pushed forward into 2020 due to various lockdowns induced by the coronavirus pandemic. The main factors are a 6.6 percent increase in the footprint due to carbon emissions compared to last year, as well as a 0.5 percent decrease in global forest biocapacity due in large part to the spike in deforestation in the Amazon – in Brazil alone, 1.1 million hectares were lost in 2020, and estimates for 2021 point to up to a 43 percent increase in deforestation over the previous year.

“As the United Nations Decade for Ecosystem Restoration is launched on World Environment Day, June 5, these data make it blatantly clear that post-COVID 19 recovery plans will only succeed in the long run if they go to key aspects such as regeneration and efficiency in the use of ecological resources,” says Laurel Hanscom, CEO of Global Footprint Network.

Each year, Earth Overshoot Day marks the date when humanity has used all the biological resources the planet’s ecosystems can regenerate over the course of an entire year. Humanity currently uses 74% more resources than the planet’s ecosystems can regenerate – or the equivalent of “1.7 Earths.” From Earth Overshoot Day to the end of the year, humanity operates in ecological debt. This debt is currently one of the largest found since the world entered ecological overshoot in the early 1970s, according to National Footprint & Biocapacity Accounts (NFA) based on United Nations data.

In 2021, the footprint due to carbon dioxide emissions from transportation remains below pre-pandemic levels. CO2 emissions from domestic air travel and road transport are projected to remain 5% below 2019 levels, while international aviation is projected to decline by 33%, according to the International Energy Agency (IEA). Global CO2 emissions related to energy consumption, on the other hand, are expected to rebound and grow 4.8% from last year as the economic recovery foments demand for fossil fuels. In particular, 2021 is expected to see a spike in global coal use, which is estimated to contribute 40% to the carbon footprint this year.

Business-as-usual must be left behind
Last year, when the pandemic struck the world, governments showed they could act quickly, both in terms of regulations and spending, putting human lives above all else. The perfect storm that is brewing, as the impacts of climate change and biological resource security converge, requires the same – if not higher – level of alertness and swift action from heads of state.

“In November, as a weary world turns its attention to Scotland and COP26, together we can prefer the Planet’s prosperity to its misery. We can and must rebuild from the pandemic – benefiting from our global capacity to plan, protect and steadily advance. Scottish innovation helped lead the industrial revolution; in 2021, the Glasgow Summit and the future we choose as a community, city, business or country offers real hope for a new zero-impact revolution,” said Terry A’Hearn, CEO of SEPA.

Through their infrastructure and regulatory powers, cities have significant opportunities to shape their resource consumption and, with it, their future. Given their exposure to risk, aligning their development plans with what resilience requires in a world shaped by climate change and biological resource constraints has become cities’ top priority, regardless of international agreements.

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 a year:

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

Global Ecological Footprint and biocapacity metrics are calculated each year in the National Footprint and Biocapacity Accounts. Using UN statistics, these accounts incorporate the latest data and the most updated accounting methodology (the National Footprint and Biocapacity Accounts 2021 Edition feature 2017 data.) To estimate this year’s Earth Overshoot Day, Ecological Footprint and biocapacity are “nowcasted” to the current year using the latest data from additional sources, such as the Global Carbon Project.

To maintain consistency with the latest reported data and science, the Ecological Footprint metrics for all past years since 1961 (the earliest year data is available) are recalculated every year, so each year’s metrics share a common data set and the exact same accounting method. The annual dates of Earth Overshoot Day are recalculated accordingly.

Consequently, it is inaccurate to simply look at media accounts from previous years to determine past Earth Overshoot Days. Indeed, a true apples-to-apples comparison of Earth Overshoot Days can only be made using the same edition of the National Footprint and Biocapacity Accounts. For instance, it would make no sense to compare the date of Earth Overshoot Day 2007 as it was calculated that year—and reported by the media at the time—with the date of Earth Overshoot Day 2020, because improved historical data and new findings such as lower net carbon sequestration by forests have slightly shifted the results. Even a few percentage points change can shift the date of Earth Overshoot Day by a good number of days.

This is why, ultimately, the precise Earth Overshoot Day date for each year is less significant than the sheer magnitude of the ecological overshoot, as well as the overall trend of the date progression year over year—which, as you now understand, is rigorously identical to that of the Ecological Footprint (given the fact that biocapacity remains basically unchanged.) Over the last decades, the date has been creeping up the calendar every year, although at a slowing rate.

The dates of past Earth Overshoot Days, as calculated with the National Footprint and Biocapacity Accounts 2021 Edition, are:

*The calculation of Earth Overshoot Day 2020 reflects the initial drop in resource use in the first half of the year due to pandemic-induced lockdowns. All other years assume a constant rate of resource use throughout the year.