© 2015 Elsevier Ltd. All rights reserved. Anthropogenic halocarbons such as chlorofluorocarbons, CCl4, and CH3CCl3 are largely responsible for the observed depletion of stratospheric ozone, yet there is a contribution by gases that are both naturally and anthropogenically produced. Of the naturally produced halocarbons, CH3Br and CH3Cl are the largest contributors to stratospheric ozone depletion, accounting for about one-quarter of the equivalent chlorine in the atmosphere. Other shorter-lived halocarbons, such as CHBr3 and CHCl3, may also be contributing, particularly as Earth's climate changes and alters their natural cycles. These shorter-lived gases also play an important role in tropospheric chemistry of the marine boundary layer.