It used to be that measuring carbon sequestration on a large scale was a difficult task.  It required multiple measurements of photosynthesis from tree branches and many small scale soil respiration measurements.  These measurements were then scaled up and used to estimate ecosystem carbon exchange.  This was often a cumbersome and not all to accurate method.

Advances in technology have allowed for measurements of carbon exchange on several scales.  Small scale branch photosynthesis and soil respiration measurements are still used, only now they are carried out in conjunction with measurements on a larger scale.  These measurements include forest level carbon exchange measurements carried out using gas exchange sensors mounted on towers in the forest or on airplanes flying over the forest.  All of these measurements are then integrated into computer models using satellite imagery and remote sensing data.