We investigated the spring frost risk over the main apple production areas in Japan under future climates using multiple sets of global circulation models and scenarios. Frost risk was judged by the daily minimum air temperature. Apple phenology was estimated with a phenology model under future meteorological conditions. Since spring cold hardiness of apple trees depends on the phenophase, we took the effect into consideration by decomposing the season into three phenophases. April temperatures are projected to increase by 0.5–2 °C for 2031–2050 and 1.5–6 °C for 2081–2100 relative to that of 1981–2000, depending on the climate models and scenarios. Spring phenology will advance by 10 days or more for the highest temperature increase case for 2081–2100. Frost risk will not monotonically change with the future temperature increase. For the scenario with the temperature increase by 1–2 °C in spring, corresponding to the medium temperature increase case among our simulation cases, frost risk will be maximized in the southern Tohoku region and central highlands, where frost risk is relatively high under the current climates. Frost risk will tend to decrease for the highest temperature increase case. During bud break to foliation, apple trees will be in highest frost risk under future climates.

中文翻译：

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日本苹果树未来霜冻风险

我们使用多套全球环流模型和情景调查了未来气候下日本主要苹果产区的春季霜冻风险。霜冻风险通过每日最低气温来判断。苹果物候是在未来气象条件下用物候模型估计的。由于苹果树的春季抗寒性取决于物候期，我们通过将季节分解为三个物候期来考虑影响。与 1981-2000 年相比，2031-2050 年 4 月的温度预计将升高 0.5-2 °C，2081-2100 年将升高 1.5-6 °C，具体取决于气候模型和情景。对于 2081-2100 年的最高温度升高情况，春季物候将提前 10 天或更长时间。霜冻风险不会随着未来温度的升高而单调变化。对于春季气温升高1-2°C的情景，对应我们模拟案例中的中等温度升高情况，在东北地区南部和中部高地，霜冻风险相对较高的地区，霜冻风险将最大化。当前气候。对于最高温度升高情况，霜冻风险将趋于降低。在萌芽到落叶期间，苹果树在未来的气候下将面临最高的霜冻风险。