Radiative efficiencies and global warming potentials of agricultural fumigants

A rounded assessment of the environmental impacts of fumigants used within the agricultural sector must consider the potential climate impacts of their release into the atmosphere. Within policy settings, the 100-year Global Warming Potential (GWP(100)) is the most commonly used metric. While GWP(100) values are available for the widely used fumigant sulfuryl fluoride, no estimates are available for 4 alternative fumigants: ethyl formate, cyanogen, hydrogen cyanide and phosphine. Existing laboratory measurements of the infrared spectra and reaction rate coefficients of these gases are used to produce new estimates of their radiative efficiencies and atmospheric lifetimes, and the first estimates of their GWP(100) and other climate emission metrics. Although uncertainties are considerable, their GWP(100) values are estimated to be no more than 2% of the GWP(100) value of sulfuryl fluoride. These new estimates will enable informed estimates of the climate impact of the use of these fumigants, which must account for the differing usage and release rates to achieve the same fumigant efficacy.