4 June 2013 | By Cang Hui
Since the concept of sustainable development was put forward by the World Commission on Environment and Development in 1987, it has become an ideal development approach and policy goal. Among the indicators of sustainable development is the ecological footprint methodology. The Ecological footprint is the total area of productive land and water ecosystems needed to produce adequate resources and absorb wastes for a given enterprise or population. Biocapacity, on the other hand, is the locally available carrying capacity (the availability of resources) of an ecosystem for generating resources and absorbing wastes. The ecological footprint and biocapacity, represent humanity’s demand for resources and the supply of resources from a regional ecosystem, respectively. As both are measured in the same unit (the global hectare: gha), it is straightforward to calculate regional ecological budget as surplus and deficit. To this end, an ecological surplus has been suggested as a minimum criterion for sustainability.
As conventional ecological footprint methodology ignores management actions and policies, it only gives limited support to decision-making. The use of spatial features, with the help of Geographic Information Systems (GIS), has helped ecological footprint methodology to overcome this shortcoming. However, in doing so, we often neglect an important issue that is associated with any spatial or area-based information, the scale dependency of spatial features. Specifically, the area sizes of different types of land cover (e.g. cropland, grazing land, fishing land, forest, built-up area and barren land).
Since area-based information has been widely used for estimating the sizes of different land covers, it is important to assess how the biocapacity estimated will be affected by the resolution of the data and whether this scale dependency will change our view on regional sustainability. In a recent paper published in the Journal of Environmental Management, C∙I∙B researchers and colleagues from Lanzhou University investigated the scale dependency of biocapacity and the potential misconception of unsustainable development.
Coarse-scale maps will shift the perception of regional sustainability towards unsustainable development. Using the typical global land cover map derived from MODIS (moderate-resolution imaging spectroradiometer) data and AVHRR (Advanced Very High Resolution Radiometer) data at the resolutions of from 250m to 1km, we could underestimate global sustainability. Although it is reasonable to fuel public awareness, we might not need 1.5 earths in 2007 for sustainable development as predicted from the Living Planet Report. It is only by fully appreciating and utilizing the scale dependencies of land covers and biocapacities that we can have an accurate picture of sustainability.
Read the paper
For more information, contact Cang Hui at chui@sun.ac.za
