Northeast Italian viticulture affected by heat and vegetation stress. A satellite-based study from 2000 to 2024

The impact of extreme temperatures on viticulture in northeastern Italy is emerging as a significant risk for farmers due to the changing climate. Rising temperatures and stronger heatwaves are exacerbating the frequency of heat and the vegetation stress on the phenology of the plants. However, the influence of climate change in extreme surface temperature and the frequency of the vegetation stress over the years in northeastern Italy's vineyards is still less explored. This study aims to analyse daytime and nighttime Land Surface Temperature (LST) and the Vegetation Health Index (VHI) from 2000 to 2024. The frequency distribution of extreme temperatures and vegetation stress was analysed using satellite data from the MODIS dataset, also considering three main vineyard classes. The study was conducted using Google Earth Engine platform, followed by a non-parametric trend analysis assessment. Results shows that nighttime LST is increasing significantly across the study area, while the daytime LST shows a significant increasing trend in flat vineyards, which are also more exposed to heat and vegetation stress. In contrast, steep and heroic vineyards are more affected by higher night temperatures. The VHI is getting worse in most of the study area, while the occurrences of the stress level increased in the 2020-2024 period. The findings could be used for structure guidelines for policy makers to design strategies to mitigate the impacts on vineyards. This work aims to stimulate further research into the effects of climate change on land surface temperature and vegetation stress in the Italian viticulture.