Earth Overshoot Day – Passing Us By?

August 2nd marked a key date in the calendar of environmental consciousness as it marked Earth Overshoot Day, the arbitrary date set up by the Global Footprint Network signifying when humans have used up all the resources that the Earth could theoretically naturally regenerate within a year. In an era when sustainability is a key issue, such dates and proclamations can gain currency, attain widespread coverage and provoke calls for change. But what is Earth Overshoot Day and how useful is it as a concept?

The issue of sustainability has established an increasingly prominent locus in the lexicon of development debates. The finality of the Earth’s resources has become progressively more scrutinised as an awareness of humanity’s role in altering earth system processes and our contribution to recent global warming trends is ever more certain. The Global Footprint Network (GFN), an international think-tank, have calculated and published details of Earth Overshoot Day since 1986 in an attempt to provide a marker to aide in the understanding of how the human economy is increasingly operating outside of the Earth’s ecological limits.

By comparing humanity’s annual consumption of natural resources to the Earth’s biocapacity – its’ ability to regenerate resources within that year – a date is calculated to signify when humans have consumed the quantity of natural resources that the Earth can naturally replenish in that calendar year. In 2017, with human demand reaching nearly 20 billion hectares and the Earth having a biocapacity of just 12 billion hectares, according to the GFN, Earth Overshoot Day was 2nd August.

However, it is not so much the significance of the day itself but its’ timing which should be of note. 1970 was a milestone year – marking the point at which humanity began depleting resources faster than they were being naturally regenerated but August 2nd 2017 is significant in that it is the earliest that Earth Overshoot Day has ever fallen, with the GFN concluding that humans now require 170% of the world’s natural output, or the equivalent of 1.7 planets, to match their demand on natural resources every year. This is an increase of 33% since the turn of the century when humanity required 1.37 planets per year*.


These statistics and figures can gain widespread currency in political debate. They lay the foundations for a biological accountancy system that can seemingly give statistical certainty and objectivity to a still subjective and controversial debate – in essence providing an accounting method of representing the discrepancy between consumption and natural renewal.

Yet its utility should still be scrutinised. Whilst the media coverage that is generated (even through articles such as this), does help to put the issue of sustainability back on the political agenda, Earth Overshoot Day lacks the long-term traction to change attitudes. It suffers from a lack of public awareness as well as the more fundamental methodological flaws as uncovered by the Breakthrough Institute.

In many respects, the pitfalls that befell the concept of Planetary Boundaries, an idea espoused by Rockstrom et al in 2009, blight the basis of Earth Overshoot Day too. The questions of accuracy in measuring humanity’s ecological footprint or nature’s regenerative capacity shroud the calculations in some doubt and controversy. Furthermore, whilst the Breakthrough Institute have, historically, had a somewhat sceptical attitude with regards to environmental indicators, particularly in relation to the aforementioned Planetary Boundaries, they are correct in identifying the inaccuracies in the calculations of the GFN.

For example, the excessive emphasis on carbon dioxide and the amount that humanity releases as a function of the carbon sequestration potential of the planet. The Breakthrough Institute argue that crop, pasture, fisheries and farming are all in equilibrium or surplus, and thus the entire overshoot is human emissions of carbon, a statistic that is then deftly translated into a proxy of land area and resource use.

However, whilst the abundance of concepts such as Earth Overshoot Day, Planetary Boundaries and Ecological Footprints serve to bring greater levels of exposure to these issues, fundamental change will only be achieved through political negotiation and international cooperation – both of which have proven painstaking in recent years and remain tortuously complex. Despite the optimism surrounding the Paris Climate Accord signed in December 2015 committing 190 nations to a 2˚C threshold in relation to global warming, there is scant belief that this can be achieved, not to mention the lack of a legally binding aspect to the treaty coupled with the recent withdrawal of the USA at the behest of President Trump, which served to underscore just how frail, fraught and transient such negotiations can be.

Whilst there are problems with the macro-level analysis and labelling of Earth Overshoot Day, the Global Footprint Network concurrently launched a calculator for computing individual Overshoot Days which would, in theory, highlight individual or national trends and dates which could potentially serve as a stimulant for change and a tool for policy makers to use during protracted political wrangling. It highlights, for example, the national disparities – the average American’s Overshoot Day is in March whilst their Chinese counterparts pass the date in July. However, if anything, this could complicate matters further – the issue of environmental responsibility as well as carrying capacity already overshadows negotiations; quibbling over arbitrary dates that change year-upon-year will not help matters.

Earth Overshoot Day should not, however, be discarded. The fact that the latest calculations indicate that the past decade has seen a deceleration in the rate of consumption should be cause for optimism. However, in terms of the wider debates surrounding sustainability, climate change and global warming, an arbitrary date can be little more than an indicator, a label and a theoretical concept.

August 2nd may have been proclaimed in the offices of the Global Footprint Network as an unprecedented indication of humanity’s insatiable demand for the planet’s resources, but in political headquarters across the globe, any alarm bells concerning the significance of the date had little resonance…



*Accounting for the GFN’s annual recalculation of all previous Earth Overshoot Dates and based upon the statistics from 2017.

(Footprint Calculator can be found at!/)


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