Climate change in Washington related emissions are the dominant source of GHG emissions and have increased from 61.2 MMT CO-equivalent (CO-e) in 1990 (excluding residual fuel for transportation) to 74.6 MMT CO-e in 2004, while their share has increased from 79% of total emissions to 85% over the past fourteen years. Carbon dioxide is the dominant GHG followed by methane, nitrous oxide, perfluorocarbon and sulfur hexafluoride. Non-energy industrial global greenhouse gas emissions have lowered from 14% to 9%, mainly due to reduced emissions from aluminum production. This has been the result of two key elements: process changes that reduced CO and PFC emissions per
Nitrous oxide runoff and leaching of fertilizers (25%), biomass burning (10%), fossil fuel combustion and industrial processes (10%), biological degradation of other nitrogen-containing atmospheric emissions (9%), and human sewage (5%). Agriculture enhances nitrous oxide production through soil cultivation, the use of nitrogen fertilisers, and animal waste handling. These activities stimulate naturally-occurring bacteria to produce more nitrous oxide. Nitrous oxide emissions from soil can be challenging to measure as they vary markedly over time and space, and the majority of a year's emissions may occur when conditions are favorable during "hot moments" and/or at favorable locations known as "hotspots". Among industrial emissions, the