Figure3

Figure 3. Box model of the biochar sequestration system. The green-outlined pools and reactions ($$ A_1 $$, $$ A_2 $$, $$ A_3 $$, and the transfers among them) reproduce the pre-industrial Anderies subnetwork; the black-outlined pools and reactions are specific to biochar and to the fossil-fuel accounting that links the total carbon stock to the atmosphere. The same convention is used in the box models of the remaining CDR systems.