Earth Overshoot Day

Reading time: 6 minutes
Key words: Climate change, environmental awareness, sustainability, ecological impact, global footprint

Today's blog is written by guest blogger Kaitlin Carlson.

Earth Overshoot Day

On August 1 2018, we, the collective citizens of Earth, had used up all of the ecological resources the planet could generate for us this year. Earth Overshoot Day passed without most of us (including myself) even knowing about it, and we continued on with business as usual - generating waste (the average Canadian generates 2.3kg of waste per DAY) and explicitly or implicitly contributing to other activities which simply aren’t sustainable.

Let me begin by providing some background on what Earth Overshoot Day really represents. It’s a metric calculated by the GlobalFootprint Network to give us an idea of how our consumption compares to earth’s production capacity using the following formula [1]:

Planet’s Biocapacity ÷ Humanity’s Ecological Footprint x 365 days = Earth Overshoot Day

Both biocapacity and ecological footprint are measured in terms of area (hectares). Biocapacity refers to the area of land and sea that is biologically productive and includes forests, grazing and crop lands, fishing grounds, and built-up land. Ecological footprint is a measure of the population’s demand for plant and animal-based food products, timber/forest products, space used for infrastructure, and forest area to offset carbon dioxide emissions (mainly from fossil fuel consumption).

In a sustainable world, Earth Overshoot Day would not exist - or at least it wouldn’t occur until December 31 of any given year. But, in the last five decades, we have consistently been hitting Earth Overshoot Day well before the end of the year. Here’s how Earth Overshoot Day has been trending since the 1970s [2].

Looks like we’ve been over-consuming for some time, and 2018 was our highest-consumption year yet - we maxed out our annual biocapacity with still five months left to go. This means that we would need 1.7 times the biocapacity of our earth just to break even. Since Earth currently does not import from other planets, this is troublesome.

There is no planet B (at least for now)! [3]

Earth Overshoot Day should give us cause for concern, and hopefully make us take action to make some serious changes. Beware though; there are well-founded criticisms of the use of Earth Overshoot Day as an indicator of our impact on the planet. The main criticism is that the calculation isn’t overly scientific. It turns out that each land use type included in the calculation is nearly balanced in biocapacity and ecological footprint except for carbon dioxide emissions [4]. What this means is that when the Earth Overshoot Day calculation tells us that we’ve consumed a year’s worth resources by August 1, it isn’t technically accurate. Rather, we've actually consumed a year’s worth of carbon, but we still have a surplus of the other resources to work with for the remainder of the year [5]. (If you want to calculate your individual carbon footprint, you might find this guide  interesting.)

On the surface this point might seem like a good thing; maybe our food production, deforestation, and construction is sustainable? (…That intuitively doesn’t seem right, does it?) The alternative solution is that the use of area (hectares) as a measurement of biocapacity or footprint must be an oversimplification. Critics argue that such a simple measure of our impact on the planet cannot capture the real consequences [6].

But, even if we accept it to be an oversimplification, Earth Overshoot Day is still a call to action that captures the attention of the public at large in terms all people can understand: we’re depleting the earth’s resources at an alarming rate. The Global Footprint Network’s #MovetheDate campaign puts the power in our hands to lessen our ecological debt to the earth. Let's see if we can collectively make changes in order to #movethedate for 2019! Calculate your ecological footprint and get ideas of how you can help move next year’s date by using this footprint tracker.

References

[1] Global Footprint Network, "Earth Overshoot Day," Global Footprint Network, 2018. [Online]. Available: https://www.overshootday.org/newsroom/past-earth-overshoot-days/. [Accessed 08 October 2018].

[2] mw238, "flickr," 29 November 2015. [Online]. Available: https://www.flickr.com/photos/mw238/23400563466/. [Accessed 17 October 2018].

[3] R. B. Richardson, "Earth Overshoot Day May Seriously Underestimate Humanity's Ecological Footprint," ScienceAlert, 30 July 2018. [Online]. Available: https://www.sciencealert.com/earth-overshoot-day-may-seriously-underestimate-humanity-s-ecological-footprint. [Accessed 17 October 2018].

[4] B. W. Brook, E. C. Ellis, P. M. Kareiva, T. Nordhaus and M. Shellenberger, "Does the Shoe Fit? Real versus Imagined Ecological Footprints," PLOS Biology, 5 November 2013. [Online]. Available: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001700. [Accessed 17 October 2018]. 

[5] F. Pearce, "Admit it: we can’t measure our ecological footprint," New Scientist Ltd., 20 November 2013. [Online]. Available: https://www.newscientist.com/article/mg22029445-000-admit-it-we-cant-measure-our-ecological-footprint/. [Accessed 17 October 2018].