Worldwide levels of N2O have been rising rapidly for decades, and the major culprit was recently confirmed to be the heavy use of nitrogen fertilizers to grow the world's food. Other less significant sources of N2O emissions include wetlands, animal and industrial waste and automobiles.
The standard method for estimating emissions levels has been to do what is called a "bottom-up inventory." This process involves listing all the activities that emit N2O, assigning an emission factor for each activity, then tallying up the emissions. However, this method can result in large uncertainties because of the way N2O is produced.
Nitrous oxide, better known as laughing gas, is an especially potent greenhouse gas because it traps far more infrared radiation than both carbon dioxide and methane. "It's present in the atmosphere at tiny concentrations -- one-thousandth that of CO2 -- but it is very potent," Fischer said. "It has a global warming potential of approximately 300, meaning it is 300 times more active than CO2 per unit mass. And it's 10 to 15 times more potent than methane."
total N2O emissions would account for about 8 percent of California's total greenhouse gas emissions. taken together with our previous estimates of methane emissions, that suggests those two gases may make up 20 to 25 percent of California's total emissions. That's starting to become roughly comparable to emissions from fossil fuel CO2.
The vast majority of the reduction efforts have been focused on CO2
http://www.sciencedaily.com/releases/2012/12/121204145914.htm
