The optimal carbon sequestration in agricultural soils : does the dynamics of the physical process matter ?

The Kyoto Protocol, which came in force in February 2005, allows countries to resort to «supplementary activities» consisting particularly in carbon sequestration in agricultural soils. Existing papers studying the optimal carbon sequestration recognize the importance of the temporality of sequestration, but overlook the fact that it is a dissymmetric dynamic process. This paper takes explicitely into account the temporality of sequestration. Its first contribution is technical : we solve an optimal control problem with two stages and a dissymmetric dynamic process. The second contribution is empirical : we show that the error made when sequestration is supposed immediate can be very significant, and we exhibit numerically the optimal path of sequestration/de-sequestration for specific benefit, damage and cost functions, and a calibration that mimics roughly the world conditions.