A global inventory of ecosystem sources of methyl bromide, an ozone destroying gas

Abstract

Stratospheric ozone depletion is affected by halogen radicals, such as bromine, which is 40 times more effective at depleting ozone than chlorine. Methyl bromide, the largest contributor of bromine to the stratosphere is both naturally and anthropogenically produced. Biomass burning, salt marsh and agriculture are reported as the largest natural sources. However, there exists a need for a global inventory as current budget estimates are uncertain, based on limited data and show a 45Gg yr-1 discrepancy between identified sources and sinks. This study re-evaluates available data and estimates global emissions using GIS. The annual flux from land cover, biomass burning and agriculture is in excess of 66.77Gg yr-1, which is more than 15Gg yr-1 greater than previously thought. The recently identified forest soil source has been shown to be significant, contributing more than 15Gg yr-1, whilst grassland sinks have been shown to degrade less than previously thought.