Comment mesurer les émissions de CO2

Les objectifs de réduction de CO2 sont généralement revus à l'issue des sommets internationaux (Kyoto, Copenhague...), européens... et clairement affichés en pourcentage. S'il est difficile de dresser le bilan carbone d'une activité ou d'un objet (bilan qui dépend de l'espace, lieu de fabrication par exemple, et du temps, moment de consommation de l'énergie nécessaire à la fabrication...), il n'est pas bien aisé non plus de calculer les émissions de CO2 imputables aux activités humaines.

La NASA's Orbiting Carbon Observatory suggère que cela serait possible depuis l'observation spatiale, piste intéressant pour éviter les débats d'experts au moment des bilans ayant des conséquences politiques et financières.

Methods for monitoring CO2 emissions have limitations, inadequate for international climate treaty

Current methods for estimating greenhouse gas emissions have limitations that make it difficult to monitor CO2 emissions and verify an international climate treaty, says a new National Research Council letter report to the administrator of NASA, Charles F. Bolden Jr.

NASA's Orbiting Carbon Observatory -- which failed to launch in February -- would have offered proof that greenhouse gas emissions could be monitored from space, as well as provided baseline data on CO2 emissions trends from a sample of cities and power plants, the report says. NASA is expected to decide in the coming months whether to launch a replacement observatory.

The observatory was not designed for treaty monitoring and verification, and because of its two-year mission life, it would not by itself have been able to track emission trends. However, no other satellite has its crucial combination of high precision, small footprint, readiness, density of cloud-free measurements, and ability to sense carbon dioxide near the Earth's surface, said the committee that wrote the report.

SOURCES : National Academy of Sciences