By John Roberts
Nitrous Oxide, or Laughing Gas as it is commonly known, is a naturally occurring greenhouse gas that has approximately 300 times more impact on atmospheric warming than carbon dioxide pound for pound.¹ What makes nitrous oxide even more problematic is that the molecules stay in the atmosphere for an average of 114 years before being removed or destroyed by chemical means, where as carbon dioxide tends to constantly cycle within the Carbon Cycle.
The thing about N2O is that it is a naturally occurring gas that among other processes, is generally created from agricultural methods by the process of nitrification and denitrification from microorganisms in soil (or salt marsh muck, which we will get into…). Incidentally, nitrate (NO3-) is a very common commercial fertilizer used all over the world and when used for commercial farming or domestic landscaping it can run off into coastal waterways many issues can arise due to the increased nutrient flow into the aquatic ecosystem.
According to a long term study (9 years) of whole ecosystem dynamics of salt marshes that undergo nutrient enrichment, the effects of increasing nitrogen have profound impacts on coastal ecosystems.² These impacts range from erosion of creek banks to increased microbial decomposition of organic matter. It was proven that the increased nitrogen caused an increase in above ground biomass and a decrease in the belowground biomass which caused the banks to be less stable which in turn caused the erosion. While this was a study on relatively small patches of land, it equates with many coastal locations and ecosystems globally that receive an anthropogenic increase in nitrogen from industrial practices.
Microbes are not only found in the soil of farms, they are also prevalent in the muck and mud of estuaries and other coastal environments. If we continue to release excess nitrogen into coastal systems there will only be an increase in N2O production from these systems as well as a decrease in stability of the land and plant material to offset this production.
We know that a natural part of the nitrogen cycle is nitrous oxide, and we know that addition of nitrogen into aquatic ecosystems increases the production of nitrous oxide which in turn has an effect on atmospheric heating of several hundred times that of carbon dioxide. The Intergovernmental Panel of Climate (IPPC) Change estimated at 3.5 teragrams (7.7 Billion lbs.) of N2O from agricultural soils in 2006. Compare this number to the 20.0 billion pounds of anthropogenic CO2 in 2009 and the fact that only 74% of total anthropogenic N2O comes from agriculture and the numbers become quite formidable, especially if you multiply the comparative impact of nitrous oxide by 300. With something as potent and long lasting as N2O we cannot afford to wait any longer to start working on the problem.