Estimating the Date ofEarth Overshoot Day 2024
David Lin, Ph.D, Mathis Wackernagel, Ph.D.

Outline1. Overview: Earth Overshoot Day Calculation
2. The Need for Nowcasting
3. Methodological Overview: Accounting for Biocapacity
4. Starting Point: National Footprint and Biocapacity Accounts
5. Nowcasting: Extending the Timeline of the National Footprint andBiocapacity Accounts
6. Nowcast results for the world: 2024
7. Relevant publicly available references

Overview: Earth Overshoot Day Calculation
Earth Overshoot Day is the day of the year on which humanity’s demandon nature exceeds the Earth’s annual biological capacity to regenerate.
In 2024, Earth Overshoot Day falls on August 1st, meaning thatbetween January 1st and August 1st, humanity’s demand for biologicalregeneration is equivalent to the planet’s entire annual regeneration.

The Need for Nowcasting
The National Footprint and Biocapacity Accounts (NFBA) are built on
official UN datasets. However, this data comes with a time delay. The
most recently reported UN data typically has a time lag of about 3 to 4
years. As a result, the National Footprint and Biocapacity Accounts
reports also have a lag time.
Earth Overshoot Day is an estimate of the current year’s consumption,
therefore, nowcasting is needed to provide an estimate of where
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humanity’s Ecological Footprint stands compared to the planet’s
biocapacity. To generate results for the World’s Ecological Footprint andbiocapacity, Global Footprint Network uses the latest data from the
NFBA and incorporates input data from additional sources to estimate
the World’s Ecological Footprint and biocapacity for the current year.
Nowcasting is distinct from forecasting. While forecasting uses models to
extrapolate data into the future, based on assumptions of how theforecasted item operated in the past, nowcasting uses actual dataassociated with the nowcasted years. Generally, this is proxy data, suchas yield fluctuations in some crops to estimate fluctuation in entire
harvest, car usage, electricity intensity, and change in housing stock.
Such proxy data can be used to estimate relative changes in Footprint of
biocapacity related resource aspects and may be superimposed over the
more complete NFBAs that end 4 years prior.
Timely estimates are needed by decision makers. Therefore, nowcastingis common for economic indicators like GDP, which in some cases arereported quarterly. Although Ecological Footprint and biocapacity does
not shift rapidly and historical trends are informative, a 4-year time lag
may be too long for decision makers as these results may not reflect
how their resource consumption and their decisions impacted the trends.
Thanks to the nowcasted estimates, the COVID-lockdown effect can
now be seen in the trajectories of many countries.

Methodological Overview: Accounting for
Biocapacity
The Ecological Footprint’s underlying research question isstraightforward: How much mutually exclusive, biologically productive
area1 is necessary to renew people’s demand for nature’s products andservices? The demands on nature that compete for biocapacity include:• food, fibre, and timber• space for roads and structures,• energy production (from hydropower to biomass), and• waste absorption, incl. CO2 from fossil fuel or cement production.

1

Before adding up the areas, they are first productivity adjusted, hence measured in global hectares. This
makes biocapacity and Footprints comparable across time and space, since the areas are weighed
proportionally to their biocapacity.
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Both biocapacity and Ecological Footprint can be tracked and comparedagainst each other, based on two simple principles:(1) Commensurability: by scaling these areas proportional to their
biological productivity, they become commensurable.
(2) Additionality: all the competing demands on productive surfaces,
i.e., the surfaces that contain the planet’s biocapacity, can be
added up.
The measurement unit used is “global hectare,” which is a biologically
productive hectare with world-average productivity. More details about
the principles and mechanics of this accounting system are documented
extensively in this literature and on Global Footprint Network’s website.
An overview of the principles is available in open-access papers in
Sustainability and in Nature Sustainability, as well as the supplementary
information of the latter.
Calculations for countries and for the world are done through the
National Footprint and Biocapacity Accounts, based on up to 15,000
data points per country per year.

Starting Point: National Footprint and Biocapacity
Accounts
Nowcasting is an extension of the latest available National Footprint andBiocapacity Accounts (2023 edition) including both:• the latest full results (1961-2019) based on a full set of UN data,and• estimates (2020-2022) based on an incomplete data set, non-UN
data, plus extrapolations.
This means that these accounts therefore offer time series from 19612022. Here we explain, how we estimated 2023 and 2024 for the world.
National Footprint and Biocapacity Accounts are comprehensive
biophysical balance sheets that compare countries’ demand on nature
with what the planet or that country’s ecosystems can renew. They buildon the premise that, materially, the most limiting factor for the humaneconomy is our planet’s ecosystems’ capacity (its “biocapacity”). They
inform us about every country’s unique sustainability challenges,
including climate change and resource constraints.

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Recognizing the overarching biological constraints to humanmetabolisms, these accounts focus on tracking a country’s material
demands (Ecological Footprint, red line in figure below), as well as theglobal demand of humanity as a whole.

Figure 1 – Humanity’s Ecological Footprint and the planet’s biocapacity in global
hectares per person from 1961 to 2022 (2023 edition). data.footprintnetwork.org

That demand is contrasted with how much biologically productive area isavailable (biocapacity, green line in figure above) within a country, whencountries are analyzed or within the world when the global context is
more relevant. Figure 1 shows the per person results of the National
Footprint and Biocapacity Accounts for the world. The same results canalso be depicted as absolutes, i.e. the total Ecological Footprint and total
biocapacity of the world. The ratio between Footprint and biocapacity
shown is the same for both perspectives.
While Footprint and biocapacity assessments are possible at any scale,
National Footprint and Biocapacity Accounts are a useful reference point

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as they are based on data from UN statistics as well as on clear
accounting principles.2
The accounts have been published and improved annually since 1997.
They have also been tested by over ten national government agencies.
The mechanics of the accounts and the results they produce have been
confirmed. For instance, both the French and the Swiss government
reviews reproduced the results within 3%.
As our priority is to emphasize the impartiality of the accounts, as of2019 we have outsourced the production of the National Footprint andBiocapacity Accounts. To serve this very purpose, Global Footprint
Network has established a new organization with external partners. This
new home for the National Footprint and Biocapacity Accounts is the“Footprint Data Foundation”, initiated by York University and Global
Footprint Network. Its sole purpose is to maintain and improve theaccounts. The new institutional arrangement for producing the accounts
is governed through an independent board to secure neutrality andscientific rigor.
Results of the latest National Footprint and Biocapacity Accounts areavailable on the open data platform at data.footprintnetwork.org, as wellas through a downloadable spreadsheet workbook (public data
package). The 2023 edition is the latest available edition. Its results
stretch to 2019, with estimates extending to 2022. The 2024 edition,
produced by York University for FoDaFo, will be available in the summerof 2024.
The 2023 edition included the following updates compared to prioreditions:• Results up to year prior (which is 2022 for the 2023 edition) areincorporated to produce estimates beyond the UN and para-UN
data.
• Fishing grounds footprint was enhanced with unreported catch andaquaculture data.
• National crop intensity was improved to better reflect multicropping.

2 National Footprint and Biocapacity Accounts are the reference point for all other Footprint analyses at otherscales, down to the product level. Footprint standards (www.footprintstandards.org) provide guidance on how
to make assessments at any scale consistent.

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Page 5 of 8• Ocean carbon sequestration data was fully sourced from the
Global Carbon Budget; this newer data set reports higher carbon
sequestration of oceans, leading to a decrease in global Ecological
Footprint estimates in the 2023 edition.
Nationally reported land use and cover is used consistently for all
European countries.

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Nowcasting: Extending the Trends of the National
Footprint and Biocapacity Accounts
To determine Earth Overshoot Day of a given year, we calculate theratio between Earth’s biocapacity and its Ecological Footprint of thatyear. To estimate this year’s date, we used a three-step process. First,
we started with the latest National Footprint and Biocapacity Accounts(2023 edition) reaching to 2022. Second, we reviewed and adjusted lastyear’s Earth Overshoot Day date, i.e., the one for 2023, which builds onthe mentioned National Footprint and Biocapacity Accounts. Last year’s
estimate was reconfirmed when reviewing it this year. Third, we
extended 2023 to 2024 to estimate this year’s date for Earth OvershootDay. We describe how we estimated the 2024 date in the following
section.

Nowcast results for the world: 2024
The 2024 estimate starts from 2023, and analyses what has changed inthat year. For 2024, the total Ecological Footprint increased by 0.5 %compared to the previous year, while total biocapacity increased by
0.4% over the same time span3. These effects combined increased theratio of Footprint to biocapacity by 0.1%. The resulting decline
corresponds to Earth Overshoot Day arriving earlier by an estimated 15
hours, still enough to move it from August 2nd to August 1st. Note that thisestimate can change in the future as more reliable data becomes
available.
The Carbon Footprint nowcast is based on CO2 emissions data fromInternational Energy Agency (IEA) and Carbon Monitor4 and ocean
carbon sequestration data from the Global Carbon Project (GCP).
As reported by IEA, the 2020 lockdowns induced by the global pandemic
resulted in an initial sharp drop in CO2 emissions, but they increased
again in the second half of the year. At the end of the year, total
emissions were reported to be 5% lower than 2019 emissions. In 2021,
3 This number represents the increase over the previous year using ‘constant’ global hectares, which aredefined using data from the latest year. Because global hectares as a unit represent the productivity of abioproductive hectare on earth with average productivity, any increase in world productivity is mirrored by agrowth in the amount of productivity represented by a single global hectare. This means that if the value of a
global hectare is recalculated for each year, world biocapacity – as measured by global hectares – should beconstant.
4

https://carbonmonitor.org/

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emissions are estimated to have bounced back to the 2019 emissions
levels. From 2021 to 2022, emissions are estimated to have increased
an additional 1.5%. From 2022-2023, IEA reports that energy-based
emissions increased by 1.1% and from 2023-2024 the carbon emissions(expressed as t CO2eq) nowcasts are based on data from Carbon
Monitor, which estimates that 0.05% decrease in carbon emissions
when comparing the period of January 1st through March 31st.
Carbon sequestration data from GCP, which includes land-use change
emissions, ocean sink, land sink, and cement carbonation sink, isavailable until the year 2022. For 2023 and 2024 we assume that thedata maintains the trajectory established since 2000, with a decrease in
the ocean carbon absorption of CO2 emissions by 0.6%.
The combined effect of decreased emissions and decreased ocean
carbon sink led to an increase in our estimations of global Carbon
Footprint, i.e., the carbon component of the total Footprint, by 0.2% from2023 to 2024.
Figure 2 below shows the nowcasting results for the world up to 2024.
The nowcast produced the following estimates:• The biocapacity for the world in 2024 is estimated at 1.5 global
hectares per person.
• Humanity’s Ecological Footprint is 2.6 global hectares per person,of which 61% is its Carbon Footprint.

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World Ecological Footprint and Biocapacity Per
Capita1961-2024
Global hectares per person

3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
1960

1965

1970

1975

1980

Ecological Footprint

1985

1990

1995

Biocapacity

2000

2005

2010

2015

2020

2025

Carbon Footprint

Figure 2 – The global Ecological Footprint and biocapacity from 1961 to 2024 in global
hectares per person. The red line is the total Ecological Footprint per person, and thegray line is the Carbon Footprint per person (a subset of the Ecological Footprint).
The green line shows the biocapacity per person. Results for 2020-2024 are nowcast
estimates; remaining data points are directly taken from the National Footprint andBiocapacity Accounts, 2023 edition with latest year change from the 2024 Edition.

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Relevant publicly available references•

Video introduction to the National Footprint and Biocapacity Accounts, including
its underlying method: www.youtube.com/watch?v=_T5M3MiPfW4 (2.5 min).

•A more general introduction is provided in the book Ecological Footprint:
Managing our Biocapacity Budget.

•

Ecological Footprint Results for countries: data.footprintnetwork.org•

The basics on the accounting method, including a guidebook on the National
Footprint and Biocapacity Accounts and a detailed paper on the calculation
method are provided here: www.footprintnetwork.org/resources/data/•

National Footprint and Biocapacity Accounts 2023 edition: Miller, E., Basturk, S.,
Dworatzek, P., & Nithianantha, A. 2023. National Ecological Footprint andBiocapacity Accounts, 2023 Edition. (Version 1.0). [Data set and metadata].
Produced for Footprint Data Foundation by York University Ecological Footprint
Initiative in partnership with Global Footprint Network.
https://footprint.info.yorku.ca•

Release Notes: National Ecological Footprint and Biocapacity Accounts, 2023
Edition, Eric Miller, April 20, 2023.
https://footprint.info.yorku.ca/files/2023/04/NFBA2023_release_notes_v1_0.pdf•

Accounting Method and recent improvements in the accounting method:www.mdpi.com/2079-9276/7/3/58 (Ecological Footprint Accounting for Countries:
Updates and Results of the National Footprint Accounts, 2012–2018)•

A free click-through license gives you access to a sample workbook (for Hungary2014) www.footprintnetwork.org/licenses/workbook-learning-license•

A comprehensive workbook with the newest Ecological Footprint and biocapacity
contains key results www.footprintnetwork.org/licenses/public-data-package-free•

Limitations and Criticisms: The Ecological Footprint has clear limitations. And
criticism drives the scientific process. All sincere criticism is helpful, whether
based on misunderstandings, new insights, or flaws in the methodology. Global
Footprint Network summarized www.footprintnetwork.org/our-work/ecologicalfootprint/limitations-and-criticisms/•

Nowcasting the global Ecological Footprint for Earth Overshoot 2022:
www.overshootday.org/2022-calculation•

Rationale and interpretation of country level results: www.mdpi.com/20711050/11/7/2164/htm (Defying the Footprint Oracle: Implications of Country
Resource Trends); Section 2 discusses key premises, comparison Footprint toother metrics•

EU fact sheet on the Ecological Footprint as part of the EC’s Beyond GDP
website and results for European countries on the EEA website (last updated in2020).

•

Biodiversity and other Ecological Footprint applications:
https://www.bipindicators.net/indicators/ecological-footprint;
https://doi.org/10.1016/j.biocon.2013.10.019 (Ecological Footprint: Implications
for biodiversity)

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•The new platform for National Footprint and Biocapacity Accounts: FoDaFo.org;
footprint.info.yorku.ca; www.OnePlanetAlliance.org•

Short video from 2005 explaining the Footprint concepts in 3 min (old, but still
provides an accurate description) www.youtube.com/watch?v=EjyrAHzthTo.

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