This paper advocates consistently defined units of account to measure the contributions of
Nature to human welfare. We argue that such units have to date not been defined by
Environmental accounting advocates and that the term “ecosystem services” is too ad hoc to
Be of practical use in welfare accounting. We propose a definition, rooted in economic
Principles, of final ecosystem service units. A goal of these units is comparability with the
Definition of conventional goods and services found in GDP and the other national accounts.
We illustrate our definition of ecological units of account with concrete examples. We also
Argue that these same units of account provide an architecture for environmental
Performance measurement by governments, conservancies, and environmental markets.