06 November 2012

Bigfoot in New Zealand?

This blog post was written by postgraduate student Grace Leung as part of the course, Research Methods in Ecology (Ecol608). Grace is one of three students that revisits a Lincoln University research area on calculating the ecological impact of New Zealanders published in the late 1990s.


Many people have heard of the concept of the ecological footprint. You might remember it being used as a way of measuring a household’s environmental impact on the popular television show “Wasted” a few years back. But what exactly is the ecological footprint and how is it calculated?

The original method of calculating ecological footprints was developed at the University of British Columbia in the early 1990s. Dr. Mathis Wackernagel and his team used national statistics to calculate the annual per capita consumption by annual productivity. The total per capita ecological footprint is calculated by summing all ecosystem areas needed for each consumption category in a set period of timeThe original method of calculating ecological footprints was developed at the University of British Columbia in the early 1990s. Dr. Mathis Wackernagel and his team used national statistics to calculate the annual per capita consumption by annual productivity. The total per capita ecological footprint is calculated by summing all ecosystem areas needed for each consumption category in a set period of time

Sound complicated? It is. The original study calculated an ecological footprint for Canada using many sources of data, research from several countries, spanning a long period of time. Because this project was so big, it is difficult to replicate for other countries and compare over time. Economists from Lincoln University in 1998, attempted to improve this method by modifying it to use sources of data that are reliably updated, then applied the model to the New Zealand economy.


By using economic, demographic and land-use data from Statistics New Zealand and the Official New Zealand Yearbook, Lincoln economists Kathryn Bicknell, Richard Ball, Ross Cullen and Hugh Bigsby created a method of calculating a country’s ecological footprint by calculating standard input-output coefficients, multiplied by the  land to value of output ratio for each industrial sector. So while Bicknell and her team’s method may not be less complicated than Wackernagel’s, their use of standardized national statistics means that it is relatively easy to monitor changes in our footprint over time. Since most developed countries record these statistics, it can also be used to compare our footprint with other countries.
Map of global ecological footprints by country (2007)
From http://www.flickr.com/photos/ielesvinyes/6782494115/












So how big is New Zealand's ecological footprint? When Bicknell and her team calculated it in 1998, our footprint was 3.49ha per person, This included 64% of our productive land being needed to support our current average level of consumption and waste production, plus imports. This accounts for the fact that we export a lot of what we produce and also import some of what we consume. Compared to the Netherlands, we have a slightly bigger ecological footprint, but smaller than that of the US or Canada.

Although comprehensive, Bicknell does admit that there are some limitations to their method, such as not including the amount of marine resources needed to support our needs. With ever growing emphasis on sustainable development and living within the means of this planet, methods of calculating ecological footprints have continued to improve since this paper was published. In 2012, Wackernagel’s Global Footprint Network, with its improved methodology, calculated New Zealand’s footprint to be 4.31ha. Although this means we are still living within the means of our productive land, when projected to the global scale, this level of consumption will require 2.43 planets. You can even calculate your own household’s footprint on Wackernagel’s Global Footprint Network. See how you compare with the New Zealand average and the rest of the world. Go on, are you a Big Foot?

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