Global yield modelling is lacking for woody perennial crops. Experimental studies suggest negative impacts on yields due to reduced water supply and increased soil salinity, as well as from warming and ozone  . Increasing CO2 is expected to increase yields, but only where other factors, such as warming, do not become yield-limiting . Many local projections include large uncertainty because of a lack of observational data and reliable parametrisation . Most perennial crop models have found large negative impacts on yield and suitability, although CO2 fertilisation and phenology are not always considered . Perennial crops are often grown in dryland areas where rainfall or irrigation water can be critical . Valverde  found that yield losses in the Mediterranean region were largely driven by reduced rainfall, with maximum estimated yield losses of 5.4% for grape, 14.9% for olive and 27.2% for almond under a relatively hot and dry scenario . Moriondo  highlight the need for perennial crop models to incorporate phenology and extreme climate events. Equally challenging is the need to estimate the impact of biotic changes, particularly climate-driven movement of pests and diseases .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report