This contribution was prompted by the article “Gross Direct and Embodied Carbon Sinks for Urban Inventories” by Mohareb and Kennedy published in this issue. The authors define two types of urban carbon sinks—direct and embodied—and discuss their relation to producer and consumer emissions (and sinks) accounting. This commentary continues that discussion by clarifying boundary considerations and definitions between producer and consumer sinks, and between direct and indirect sinks.
Extending the notion of production- versus consumption-based emissions accounting, a corollary for producer and consumer sinks can be drawn. Producer sinks would include direct sequestration through industrial and private activities occurring within a defined territory. Consumer sinks would refer to direct and indirect sequestration activities associated with the consumption of goods and services within the same territory, wherever that sequestration may occur.
As with emissions accounting, in carbon sinks accounting I propose that the exact categorization depends on the perspective taken. Clear boundaries and well-defined terminology—historically present in emissions accounting—are critical to this novel approach to sinks accounting.