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Arctic stratospheric ozone depletion is closely linked to theoccurrence of low stratospheric temperatures. There are indicationsthat cold winters in the Arctic stratosphere have been getting colder,raising the question if and to what extent a cooling of the Arcticstratosphere may continue into the future. We use meteorologicalreanalyses from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim and NASA's Modern-Era Retrospective-Analysis for Research and Applications (MERRA) for the past 32 yr together withcalculations of the chemistry-climate model (CCM) ECHAM/MESSy Atmospheric Chemistry (EMAC) and models fromthe Chemistry-Climate Model Validation (CCMVal) project to infer radiative and dynamical contributions tolong-term Arctic stratospheric temperature changes.  For the pastthree decades the reanalyses show a warming trend in winter and coolingtrend in spring and summer, which agree well with trends from the Radiosonde Innovation Composite Homogenization (RICH) adjusted radiosonde data set.  Changes in winter and spring are causedby a corresponding change of planetary wave activity with increases inwinter and decreases in spring. During winter the increase ofplanetary wave activity is counteracted by a residual radiatively inducedcooling. Stratospheric radiatively induced cooling is detectedthroughout all seasons, being highly significant in spring andsummer. This means that for a given dynamical situation, according toERA-Interim the annual mean temperature of the Arctic lowerstratosphere has been cooling by−0.41 ± 0.11 K decade<sup>−1</sup> at 50 hPa over thepast 32 yr. Calculations with state-of-the-art models fromCCMVal and the EMAC model qualitatively reproduce the radiatively induced cooling forthe past decades, but underestimate the amount of radiatively inducedcooling deduced from reanalyses.There are indications that this discrepancy could be partly related toa possible underestimation of past Arctic ozone trends in the models.The models project a continued cooling of the Arctic stratosphere overthe coming decades (2001–2049) thatis for the annual mean about 40% less than the modeled cooling for the past, dueto the reduction of ozone depleting substances and the resulting ozonerecovery. This projected cooling in turn could offset between 15 and 40%of the Arctic ozone recovery

Radiative and dynamical contributions to past and future Arctic stratospheric temperature trends