Mapping Current and Projected Chilling Hours for Fruit Trees Using Different Scenarios under Different Locations in Egypt.

This study aims to quantify the actual (2022 and 2023) and anticipated (2020-2039, 2040-2059, 2060-2079 and 2080-2099) chilling hours estimated by the 7.2°C and 10°C thresholds for fifty stations in Egypt under five climate change scenarios (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). The results are mapped using ARC GIS to demonstrate chilling hours for any point at a given scenario and time. Median temperatures for the actual and projected monthly and annual minimum temperatures are discussed. Winter minimum temperature increases from one scenario to the next and from one projection period to the next. The lowest winter average minimum temperature is projected to be 10.2 (9.6-10.8°C) under the SSP1-1.9 scenario for the first projection period, while the highest was 13.9 (12.6-15.3°C). Under SSP1-1.9 scenario, twelve locations receive >100 hours, three of them are in Sinai (Nueibaa; Catherine; Nekhel), which they receive 497, 361, and 276 hrs. below 7.2°C, respectively. Under the rest of the scenarios, no station receives more than 100 hrs. below 7.2°C. Similar trends with more details were found for chilling hours below 10.0°C. The results show that chilling hours less than 7.2°C in Nueibaa will receive 489, 407, 350, and 309 hrs. for the projection periods 2020-2039, 2040-2059, 2060-2079 and 2080-2099, respectively. Eight locations receive between 100-200 hrs. for the projection period ending 2039. These results emphasis the need for allocating currently cultivated fruit trees species and cultivars physiologically require chilling hours to examine appropriate adaptation measures for mitigating anticipated yield reduction.