Assessments of long-term ozone depletion by CFCs have relied on their relative effects as quantified by ozone depletion potentials (ODPs). These long-term ODPs, based on steady-state atmospheric impacts, are not appropriate for making shorter-term (decade-scale) forecasts. Time-dependent ODPs, derived using an empirical approach, show that some of the hydrochlorofluorocarbons proposed as replacements for CFCs may induce significant ozone destruction in the short term.