Resource footprints and their ecosystem consequences

A meaningful environmental impact analysis should go beyond the accounting of pressures from resource use and actually assess how resource demand affects ecosystems. The various currently available footprints of nations report the environmental pressures e.g. water use or pollutant emissions, driven by consumption. However, there have been limited attempts to assess the environmental consequences of these pressures. Ultimately, consequences, not pressures, should guide environmental policymaking. The newly released LC-Impact method demonstrates progress on the path to providing this missing link. Here we present “ecosystem impact footprints” in terms of the consequences for biodiversity and assess the differences in impact footprint results from MRIO-based pressure footprints. The new perspective reveals major changes in the relative contribution of nations to global footprints. Wealthy countries have high pressure footprints in lower-income countries but their impact footprints often have their origin in higher-income countries. This shift in perspective provides a different insight on where to focus policy responses to preserve biodiversity.


LC-Impact: Origin of the factors and further discussion
LC-Impact was originally a research project that was funded by the European Union under the seventh framework programme, with the aim to establish new and further existing life cycle impact assessment categories.
After its termination, efforts were undertaken to transform the outcomes of the project into one working methodology, also called LC-Impact. All categories of LC-Impact are thus based on either existing impact categories from previous approaches, such as ReCiPe 1 , or are based on peer-reviewed publications. The complete information and background to each chapter can be found in individual chapters on www.lc-impact.eu. In Table S1 the most relevant background information for each impact category we used here, is given. We assumed the same CF for fossil and biogenic CO2.

S3
Some of the impacts calculated in the main paper are above a PDF of 1, i.e. well above what one would commonly assume to be a fraction. This is mostly caused through the time-integration of the impacts since we integrate the continuous impact one pulse has over the entire timeframe considered. For example, a pulse of a CO2 emission will stay active within the atmosphere for years and constantly contributes to climate change. The period considered for climate change is usually 100 years. Impacts from e.g. eutrophication, on the other hand, have a nearly instantaneous effect and cease after the nutrients excess has been absorbed. Nevertheless has each emission or resource use a time dimension associated with it (use per year or emission per year). Therefore, there is also a time dimension included in the characterization factors.

Alignment of production and impact locations
Since trade data is available on a national level only, we aggregated all characterization factors on the corresponding level. However, this raises the question whether production happens actually in the areas where impacts are likely to happen or not. Such an alignment in spatial detail is relevant for example for water consumption. Due to the rather high impacts in the US, we use the US as an example here. We use maize, wheat and cotton as examples, being among the most important crops in the US ( Figure S1). Maps for the use of irrigation water for crops are from ref 21 . The water for irrigation is mainly used for in areas with a high characterization factor. This contributes to the explanation of the magnitude of the impact in the US.

Pressure footprint vs. Impact footprint
In Table S1 we can see the difference between net exporting and importing countries in terms of pressure footprints or impact footprints.

Maps and scatterplots of pressure and impact footprints
In the following figures ( Figures S1 to S9), the maps of the impact footprints and the scatterplot showing the comparison between pressure footprints and impact footprints are presented. The later show the standardized relations of the pressure vs. impact footprint relations. Due to many small countries with relatively low impacts/pressures, we also provide log -standardized graphs which better depict the relationships for these small countries (Figures S11-S21).  Figures S11-S21 depict the standardized Pressure vs Impact footprints of all dicscussed accounts (corresponding to Figure 3 of the main text and Figures S2 -S11 in the Supplements) on a double logarithmic scale. This scale provides a better representation of the footprints relationships for countries with smaller footprints. In order to remove negative values for the logarthmic transformation, the minimal occuring standardised value (per account) was added to all standardized values of the corresponding account.