What is the GWP and atmospheric lifetime of nitrous oxide?

What does GWP mean?

         GWP, short for Global Warming Potential, is a climate-change based metric used to measure how much different greenhouse gases contribute to global warming. Global Warming potential (GWP) is a relative measure that compares the ability of different greenhouse gases to heat the Earth's atmosphere per unit of time.

              Common greenhouse gases are water vapor (H 2O), ozone (O 3), carbon dioxide (CO 2), nitrous oxide (N 2O), methane (CH 4), hydrochlorofluorocarbons (CFCs, HFCs, HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF 6).

（IPCC Second Assessment Report）

Nitrous oxide emissions

Nitrous oxide (N2O) accounts for 6% of all greenhouse gas emissions from human activities. Human activities such as agriculture, fuel combustion, wastewater management and industrial processes are increasing the amount of N2 O in the atmosphere. Nitrous oxide is also part of the Earth's nitrogen cycle and occurs naturally in the atmosphere from a variety of natural sources. Nitrous oxide molecules remain in the atmosphere for an average of 121 years before being removed by sinks or destroyed by chemical reactions. One pound of carbon dioxide has 265 times the warming effect on the atmosphere than one pound of carbon dioxide.

Globally, 40% of N2 emissions come from human activities. 2 Sources of nitrous oxide emissions include agriculture, land use, transportation, industry and other activities described below.

• Agriculture. Nitrous oxide can come from a variety of agricultural soil management activities, such as applying synthetic and organic fertilizers and other planting methods, managing manure, or burning agricultural residues. Agricultural soil management is the largest source of CO2 emissions. Although not shown in detail in the figure and less important, N2O emissions are also a result of land use and land management activities
  
• Fuel burning. Nitrous oxide is emitted when fuel is burned. The amount of N 2O emitted from burning fuel depends on the fuel type and combustion technology, maintenance and operating practices.
  
• Industry. Nitrous oxide is a byproduct of the production of chemicals such as nitric acid, which is used to make synthetic commercial fertilizers, and adipic acid, which is used to make fibers such as nylon and other synthetic products. Other applications such as anesthesia and semiconductor manufacturing also produce nitrous oxide.
• Wuss. In the process of domestic sewage treatment, nitrous oxide is also produced in the process of nitrification and denitrification of nitrogen, usually in the form of urea, ammonia and protein.