Centre for Integrated Sustainability Analysis
@ The University of Sydney

Energy and emissions land - incorporating the impacts of climate change into the Ecological Footprint

In addition to emissions of CO2 from energy use, our Ecological Footprints include emissions of other greenhouse gases, and also emissions due to other sources such as land clearing, enteric fermentation in livestock, industrial processes, waste, coal seams, venting and leakage of natural gas, all of which are particularly important in Australia.

'Energy land' is conventionally calculated conventionally using either a carbon sequestration factor, or a 'fuelwood equivalence' factor. Hypothetical 'fuelwood land' is also responsible for the global 'overshoot', or the 'carbon sink deficit'. However, the choice of forest type (native or introduced species) and planting location (disturbed or degraded land, arid or temperate climate) significantly influence both the amount of land required and the sequestration rate. Moreover, subject to geographical, climatic and technological circumstances, there may be better options for a population to reduce or compensate its emissions. Substituting renewable energy for fossil energy sources, improving energy efficiency, fuel mix changes or structural economic shifts are already existing alternatives. Some authors have even argued that current methods are too inaccurate to include land for sequestering greenhouse gas emissions in the ecological footprint. A national greenhouse gas account could instead be presented as complementary to an ecological footprint account (see National Environmental Accounting).

If it is considered important to produce a single-point indicator (that is, to combine land use and greenhouse gas emissions in the ecological footprint), a disturbance-based approach is most suitable for measuring 'emissions land'. According to the Intergovernmental Panel, Climate change is predicted to cause temperature and sea level rises, and thus widespread disturbance to natural ecosystems. A populations climate change impact can therefore be characterised as the projected land disturbance due to climate change caused by the greenhouse gas emissions of that population. It must be emphasised that climate change projections are highly uncertain. However, an advantage of a disturbance-based approach is that ecological footprints can be calculated for different abatement strategies and emissions scenarios, which can be compared to a business-as-usual baseline figure.