Perturbation to global tropospheric oxidizing capacity due to latitudinal redistribution of surface sources of NO x , CH 4 and CO

Economic and social projections indicate that during next several decades there will be major geographical redistribution of surface emissions of O 3 precursors, such as NO x , CH 4 and CO. A net decrease in their emissions from northern hemispheric mid‐latitudes will be accompanied by substantial increases from the tropics. We have investigated a hypothetical scenario of currently underway transition of such emission patterns using a global two‐dimensional photochemical model. With overall O 3 precursor releases held constant, a simultaneous transfer of their emissions by 25% from the latitude belt 75°N–35°N to 5°S–35°N increases tropospheric oxidizing capacity such that the methane global lifetime and concentrations fall by more than 3%. Seasonally dependent changes in surface O 3 concentrations are also calculated. In influencing OH concentration, redistribution of surface NO x emissions is 2–3 orders of magnitude more efficient per unit mass than CO emissions. Shifts in methane sources have insignificant effects on global photochemistry, but lead to a decrease in its interhemispheric gradient.