Calculating national and global ecological footprint time series: resolving conceptual challenges

This study addresses the conceptual challenges that emerge when calculating Ecological Footprint time series. Building on core concerns arising from the various existing Footprint time series at the national and global scale, this paper discusses conceptual and methodological implications, and suggests improvements for enhancing the clarity, validity and reliability of Ecological Footprint results. Unlike static accounts, time series show trends that allow researchers to test the noise in the data. Also, time series offer the opportunity to examine results and question interpretations, a fertile ground for comparing methodological alternatives. This paper addresses two conceptual issues that determine method design: the specific meaning and measurement challenges of ecological overshoot; and the range of research questions that can be addressed with productivity-adjusted hectares versus actual hectares. The conclusions from this discussion build the groundwork for showcasing time series for three countries.