December 7, 2021

I, Science

The science magazine of Imperial College

The earliest ever Earth Overshoot Day this year seemed to pass without much notice ...


In London this summer, August the 20th passed in the usual blur of urbanised flurry; tubes were packed with the rush hour crush, people sunbathed in the park, pavements sweltered under the heat and generally it was just another sunny Tuesday in the city.

For the few that read the smaller stories hidden within the national papers, they would have realised that this day was Earth Overshoot Day. This is the theoretical point in the year when we overtake nature’s annual budget of resources and from then on operate on a sort of ecological overdraft. From this point it is said that we are reducing more stocks and accumulating more greenhouse gases in the atmosphere than can be reversed by the capacity of the Earth within a year.

But just how significant is this date? Is the timestamp an accurate measure of consumption or is it just a publicity stunt? Are more drastic measures needed to communicate to the general public the true extent of the damage we are inflicting on our resources?

Can we afford to overlook Earth Overshoot Day?

The idea of calculating this date was the brainchild of the New Economics foundation, although it is now propagated by the Global Footprint network, an international not-for-profit organisation that develops and promotes sustainability and ecological awareness. They estimated that this tipping point initially crawled into our calendars in 1975, as before then the ecological footprint of every person could be accommodated by the finite resources across the world. Since 1975, the trend has been for date to come earlier and earlier each year; last year the day fell on August the 22nd, and the year before it was September the 27th.

The date itself is an approximation based on the seemingly simplistic equation of dividing the world’s biocapacity by its ecological footprint, both measured by a unit called a global hectare. A global hectare is a measure of physical area and how biologically productive it can be; whether it can sustain crops for food, has forestry for carbon dioxide absorption or has a high rainfall to contribute to water reserves, amongst other characteristics.

This is by no means an exact science. The methodology used to convert the contributions of say, a stretch of rainforest in Brazil or a fishery in Alaska into the numerical value of a global hectare is complex and relies on leaps of faith in parts. Conversion of the composite data into a calendar date is even more cavalier and so merely offers a simplistic, metaphorical concept for members of the public to understand. In reality, years do not reset and the deficit is not written off on December the 31st – the depletion is ever ongoing beyond the limits of the Gregorian calendar.

So, for the few reading the story on Earth Overshoot Day buried deep in their daily paper, what was the message they took? Did they stop to think about increasing their recycling, reducing the carbon emissions caused by their commute to work, or modify shopping habits to reduce the strain on landfill sites? Did any actually change their ways? Although there is no way to know the effect of this campaign for sure, it seems that the collective effort of every single plea on the subject of resource management falls on deaf ears. It is currently predicted that we require around 1.5 theoretical Earths to satisfy our current global hectare demand, and the resource demand is ever-increasing.

Earth Overshoot Day is one of many ways to publically communicate the excessive lifestyle we, as an international community, are collectively indulging in, but it offers no solutions or incentives for people to change their lifestyles for the better. Government pressure needs to increase. Tackling industrial consumption alongside day-to-day public consumption is vital, but communication to the consumers is still proving difficult.

We are a distracted population in the capital, and it is easy to get swept up in our daily tasks without pausing to spare a thought for the world outside the M25. Is making people momentarily stop and think about our ecological debt while they read Metro on the tube enough? I personally doubt it. Having an international Earth Overshoot Day is interesting in concept, but if it’s overlooked so easily by the media and not influential enough to trigger a lifestyle change in the public, much of its message is diminished. Sadly, if the message diminishes, the hope of reversing the damage we’re inflicting on the planet diminishes too.