How sensitive is tropospheric oxidation to anthropogenic emissions?

Abstract

We use a global chemistry transport model to explore how changes in anthropogenic emissions alter ozone production and tropospheric oxidizing capacity over decadal (1990–2010) and centennial timescales (1900–2100). We find that the spatial extent of O3 production and loss in the troposphere changes very little despite large projected increases in precursor emissions. While tropospheric OH shows a long‐term decrease of only 20% between 1900 and 2100, there are widespread changes in distribution which alter regional oxidation capacity substantially. We show that the remote marine boundary layer remains an important net sink of O3, as greater production related to increased continental NOx emissions is outweighed by greater O3 destruction. The critical NOx level required to support net O3 production doubles between 1900 and 2100, from 28 to 55 pptv on average, preventing any large‐scale shift in production regime.