POSSIBLE VARIATIONS IN ATMOSPHERIC METHANE.

A model coupling photochemistry and vertical transport in the troposphere has been used to investigate the magnitude of possible future perturbations to atmospheric CH//4. The response of atmospheric CH//4 to an increase in the concentration of CO or to a variation in stratospheric O//3 has been studied. Both of the above mechanisms arise because a change in the concentration of tropospheric OH will lead to a change in the CH//4 abundance. The calculations imply that a perturbation of about 30-40% in atmospheric CH//4 could occur if stratospheric O//3 were perturbed by 10% of if man-made CO continued to increase. The possible consequences of a CH//4 perturbation may entail a perturbation in stratospheric photochemistry or in the thermal balance of the atmosphere