Activity data
The measure of how much of an activity occurred — hectares converted, litres combusted — multiplied by an emission factor to estimate emissions.
Emission estimates almost always take the form of activity data multiplied by an emission factor. Activity data supplies the extent or quantity; the factor supplies the intensity.
In land-use accounting, activity data means hectares of deforestation, area burned, volume harvested or area restored, usually derived from satellite change detection and refined with field evidence. Its accuracy is often the dominant source of uncertainty in the final estimate, because extent errors scale the whole calculation.
Because of that leverage, verification concentrates on how the activity boundary was drawn: minimum mapping units, whether small clearings count, how regrowth is treated, and whether the same land is counted twice across years.
Frequently asked questions
Which matters more, activity data or emission factors?
Usually activity data, because its error multiplies across the entire area rather than a single parameter.
Can activity data be audited independently?
Yes. Imagery archives allow an assessor to re-run change detection independently and compare areas.