Nitrous oxide inside the cells, by a process catalyzed by the enzyme nitrous oxide reductase. Nitrous oxide has significant global warming potential as a greenhouse gas. On a per-molecule basis, considered over a 100-year-period, nitrous oxide has 298 times the atmospheric heat-trapping ability of carbon dioxide (), however, because of its low concentration (less than 1/1000 of that of ), its contribution to the greenhouse effect is less than one-third that of carbon dioxide, and also less than water vapour and methane. On the other hand, since 38% or more of the entering the atmosphere is the result of human activity, and
Low-carbon diet and rail releases carbon dioxide (CO2), the primary gas responsible for global warming. Chlorofluorocarbons (CFCs) are emitted from mechanical refrigerating and freezing mechanisms – both staples in food shipment and storage. Anthropogenic methane emission sources include agriculture (ruminants, manure management, wetland rice production), various other industries and landfills. Anthropogenic nitrous oxide sources include fertilizer, manure, crop residues and nitrogen-fixing crops production. Methane and nitrous oxide are also emitted in large amounts from natural sources. The 100-year global warming potentials of methane and nitrous oxide are recently estimated at 25 and 298 carbon dioxide equivalents, respectively. Steinfeld et al. estimate that