Anthropogenic Greenhouse Gases

Recent IPCC reports have clearly established the causal link between global warming and an increase in the atmospheric concentration of greenhouse gases influenced by human activities. The main contributors to this warming are carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O), which contribute 56%, 24% and 8%, respectively, to the additional greenhouse effect and whose anthropogenic emissions have been constantly increasing since the beginning of the industrial era. This chapter presents the contribution of spatial observation to the monitoring of changes in the atmospheric content of anthropogenic greenhouse gases and their emissions, focusing mainly on CO 2 and CH 4 , with N 2 O remaining a poorly observed gas with no real observation perspective at present. CO 2 is exchanged cyclically between three reservoirs: the atmosphere, oceans and the continental biosphere.