A transect is an analytical tool used by scientists to survey quantities and their distribution. Repeated measurement along given transect over time can describe the change or flux in quantity of a particular substance or population within a bounded area. Our line serves as our reference,
a consistent datum along which we can measure the ebbs and flows of molecular carbon as it is absorbed and emitted over geologic, planting, or construction cycles. We can choose any degree of precision and use any scale – molecular, anthropometric, territorial, or global – to examine the atmospheric impacts of human settlement, whether an individual building or the massive aggregations of constructed habitation we call cities. The line is our carbon transect.