Climate Change Projections Indicate Shifts in Phenology for Willamette Valley Pinot noir

<h3>Abstract</h3> <h3>Background and goals</h3> Climate change is a growing concern for winegrape producers worldwide. Increasing temperatures may accelerate grapevine development, which can change the timing of key phenology stages and affect final crop quantity and quality. Many researchers have explored the relationships between grapevine physiology and temperature-based phenology models. However, these models perform inconsistently from one region to another, especially when models calibrated in one context are applied where pedoclimatic factors and vineyard management methods differ. <h3>Methods and key findings</h3> Temperature-based phenological models were calibrated using observed grapevine phenology dates from 2012 to 2021 for 18 commercial Pinot noir vineyards across Oregon’s Willamette Valley. Model performance during cross-validation was assessed using root mean squared error, model efficiency, and % accuracy. Resulting models were used to project phenology dates from 2020 to 2100 under four climate change scenarios. By the end of century, mean bloom, veraison, and harvest dates were projected to occur 1 to 2 wk (low-emissions scenarios) and 3 to 4 wk (high-emissions scenarios) earlier than current averages. Budbreak dates are projected to advance ~10 days for most emissions scenarios. <h3>Conclusions and significance</h3> These results represent valuable information that Willamette Valley winegrape producers can use to anticipate challenges and make informed decisions to address potential long-term climate change impacts.