Assessing the Impact of Climate and climate Change on Wine Grape Productivity in Italy: The Role of Convection-Permitting Models

Italy is a world leader in viticulture and wine business. However, the sector is facing challenges due to climate change, underscoring the necessity for reliable localised data on the future impacts of climate change on viticulture. The km-scale climate models, known as convection-permitting models (CPMs), are proven to provide a more reliable representation of atmospheric fields in high-resolution compared to coarser resolution models, but their use for impact studies is still limited. Here, we fill this gap by exploring the use of climate models, including CMP, in simulating wine grape productivity at a local scale in Italy.

In particular, the study utilises a range of temperature- and precipitation-based bioclimatic indices to analyse the potential impact of climate variability on viticulture. The indices are derived from the E-OBS dataset, the high-resolution climate reanalysis product SPHERA, the CNRM climate model at both regional (CNRM-ALADIN) and convection-permitting (CNRM-AROME) scale. The analysis employs both single and multiple regression approaches to establish the correlation between the productivity data provided by two Italian wine consortia and the bioclimatic indices over the period 2000-2018. The findings indicate a robust correlation between productivity and temperature-based bioclimatic indices, particularly within the context of northern Italy, with the multiple regression approach explaining between 45% and 64% of the total variability in productivity, depending on the case.

Climate models appear to be a useful tool for explaining productivity variance. The added value of CPM is evident when precipitation-based indices are relevant in controlling the yield variability. Moreover, one of the main advantages of using climate models, rather than re-analysis or observational data, is the possibility to examine future scenarios. Therefore, the CNRM-AROME simulation, driven by ERA-Interim, is used to build a multiple regression model for wine grape productivity in Italy in the period 1986-2005. The statistical model is then used to predict the future yield (2090-2099) under the RCP 8.5 emission scenario. The results are expected to provide valuable insights that will be useful for future adaptation strategies in the viticultural sector and pave the way for more widespread use of the CPMs in impact studies.