Global Footprint Network announced that “Earth Overshoot Day” this year fell on September 27^th, the day when human demand exceeded the regenerative capacity of the natural biosystem in a year. This means that we will maintain “ecological debt” with three months remaining to the end of the year. The indicator used is derived from the Ecological Footprint analysis, a method that is fast gaining attention in recent years. Here, I would like to give an overview of the Ecological Footprint analysis, and the significance of what it analyses, “Earth Overshoot Day”.

Ecological Footprint Analysis

Ecological Footprint analysis was developed in the early 1990s by Professor William E. Rees and Dr. Mathis Wackernagel of the University of British Columbia, Canada. It is an indicator that measures sustainability by comparing human demands on the biosystem (ecological footprint) with the supply of resources that can be regenerated (biocapacity) in one year. The largest advantage of this indicator is the expression of ecological debt in terms of land size, which makes it easy to “visually” understand the finiteness of our resources and the life one Earth can support.

Figure 1. Ecological Footprint
(Source: Global Footprint Network)

For example, the food we have on our table every day such as rice, vegetables, meat, dairy products, etc., all requires arable land or pasture land. Similarly, we also need forested areas to provide the wood for wood products such as furniture. Ecological footprint is the accumulated amount of all these land and water areas required to support our lives. The higher this amount is, the “bigger our ecological debt” becomes. (Refer to Figure 1)

On the other hand, biocapacity refers to the ability of an ecosystem to regenerate resources and to absorb wastes generated by humans. Figure 2 shows the biocapacity which the Earth can supply as a percentage of land area. It alarmingly shows that only 22% of the Earth’s surface is made up of highly productive land and water areas, while the remaining 78% is desert, barren land, ice sheets, or water areas with low productivity.

Figure 2. Biocapacity
(Source: “Ecological Footprint Report Japan 2009”)

In the process of calculating Ecological Footprint and biocapacity, the actual land area is converted to global hectares (gha). 1 global hectare is defined as the “world-average productivity of a hectare of land and water area to generate resources and absorb wastes.” By using this uniform standard, Ecological Footprint and biocapacity of the world (and between countries) can be compared and analyzed.

Overshoot occurs when human Ecological Footprint exceeds the Earth’s capacity. From the latest research, it is discovered that human Ecological Footprint has already been overshooting since the 1970s. What is alarming is that even with the global economic downturn since 2008, the trend for resource demands has not stopped increasing. If this continues, the biocapacity of two Earths will be required before mid century.

Earth Overshoot Day

Global Footprint Network was established by one of the developers, Dr. Mathis Wackernagel in California, in 2003 to standardize, develop and popularize the methodology used in Ecological Footprint analysis. One of its main activities is the maintenance of the National Footprint Account, and every year from 1961 it has been releasing the respective Ecological Footprint and biocapacity estimates of more than 200 countries shown in a time series from the latest results.

Figure 3. “Ten-in-Ten” Action Plan
(Source: Global Footprint Network) (enlarge figure)

In 2005, it launched the “Ten-in-Ten” initiative, with the goal of “institutionalizing the Ecological Footprint in actual policies in at least ten national governments with ten years.” Seven countries - Finland, Wales, Switzerland, Scotland, UAE, Japan, Ecuador - have already formally adopted it or have decided to do so. (Refer to Figure 3 Phase III)

The “Earth Overshoot Day Campaign” was launched in 2006. Earth Overshoot Day marks “the day when human Ecological Footprint in a given year exceeds the biocapacity that the Earth can regenerate in that year.”“Ten-in-Ten” activities target governments while this campaign aims to raise public awareness of the fact that our balance of ecological budget is crumbling.

Earth Overshoot Day fell on September 27^th this year. In other words, we have used up the annual biocapacity that the Earth can regenerate in just nine months. This is similar to spending our annual income with three months remaining to the end of the year, and using our bank savings to survive. Overshoot compounded annually is called “biological deficit” and is related to deforestation, decrease in fish numbers and global climate change.

There are still people, however, who cannot escape from the framework of current economic models, and do not doubt that technological innovations through economic expansion and market price adjustment functions can solve environmental problems.

To this, Mathis Wackernagel, President of Global Footprint Network warns, “If we are to maintain stable societies and good lives, we can no longer sustain a widening budget gap between what nature is able to provide and how much our infrastructure, economies and lifestyles require.”

There is only one Earth. Are we truly aware of this simple truth. Earth Overshoot Day is perhaps “Earth’s challenge” to us to think about this question.

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