Amplified potential for vegetation stress under climate change-induced intensifying compound extreme events in the Greater Mediterranean Region

Abstract. The Mediterranean Basin is one of the regions most affected by climate change. It is highly dependent on the impact of climate change on agricultural efficiency and food security. While rising temperatures and decreasing precipitation levels already impose great risks, the effects of compounding extreme events (CEEs) can be significantly more severe and amplify the risk. It is therefore of high importance to assess these risks under climate change on a regional level to implement efficient adaption strategies. This study focuses on False Spring Events (FSEs), which impose a high risk of crop losses during the beginning of the vegetation growing period, as well as Heat and Drought-based CEEs (HDCEs) in summer, for a high-impact future scenario (RCP8.5). The results for 2070–2099 are compared to 1970–1999. In addition, deviations of the near-surface atmospheric state under FSEs and HDCEs are investigated with the aim to improve the predictability of these events. We apply a multivariate, trend-conserving bias correction method (MBCn) accounting for temporal coherency between the inspected variables derived from EUR-CORDEX. This method proves to be a suitable choice for the assessment of percentile threshold-based CEEs. The results show a potential increase in frequency of FSEs for large portions of the study domain, especially impacting later stages of the warming period, caused by disproportionate changes in the behavior of warm phases and frost events. Frost events causing FSEs predominantly occur under high-pressure conditions and northerly to easterly wind flow. HDCEs are projected to significantly increase in frequency, intensity, and duration, mostly driven by dry, continental air masses. This intensification is multiple times higher than that of the univariate components. This study improves the understanding of the unfolding of climate change in the Mediterranean and shows the need for further, locally refined, investigations and adaptation strategies.