The protection of natural capital, including its ability to renew or regenerate itself, represents a core aspect of sustainability. Hence, reliable measures of the supply of, and human demand on, natural capital are indispensable for tracking progress, setting targets and driving policies for sustainability. This paper presents the latest iteration of such a measure: the Ecological Footprint. After explaining the assumptions and choice of data sources on which the accounts are built, this paper presents how the newest version of these accounts has become more consistent, reliable and detailed by using more comprehensive data sources, calculating and comparing yields more consistently, distinguishing more sharply between primary and secondary production, and using procedures to identify and eliminate potential errors. As a result, this method can now provide more meaningful comparisons among nations' final consumption, or their economic production, and help to analyze the Ecological Footprint embodied in trade. With the higher level of detail, the accounts can generate sectoral assessments of an economy or, as shown in a complementary paper in this series, time trends of all these aspects. (C) 2003 Elsevier Ltd. All rights reserved.
