Nitrous oxide (N_2O) emissions from human waste in 1970-2050

摘要

Nitrous oxide (N_2O) is an important contributor to climate change. Human waste is an important source of N_2O emissions in several world regions, and its share in global emissions may increase in the future. In this paper we, therefore, address N_2O emission from human waste: collected (from treatment and from sewage discharges) and uncollected waste. We review existing literature on emissions and emission factors, and present region-specific estimates of N_2O emissions and their past and future trends. We show that human waste may became an important source of N_2O emissions in the coming years as a result of increasing urbanization. About two-thirds of the global emissions are from uncollected waste, and about half from South Asia. We argue that more research is needed to improve emission factors.