Historical Change and Future Projection of Spring Frost in China

Spring frost is one of the most critical extreme events related with agriculture in northern temperate zone. In the context of climate change, research on the previous tendency and probable future change in the spring frost all over China can enhance people’s understanding, and it also has some reference value for adjustment of agricultural structure. Using a non-parametric method that is not sensitive to outliers and takes into account autocorrelation as the method of trend analysis, this study first analyzed the historical changes based on the meteorological observation data from 1960 to 2020. Then, based on the climate data simulated by 24 models in Coupled Model Intercomparison Project Phase 6 and the results of model evaluation, the future trend in spring frost from 2021 to 2100 was analyzed under the moderate radiative forcing scenario (SSP2-4.5), including the spatial distribution and national average anomalies compared with the 1991–2020 climatology. The main conclusions are summarized as follows: 1) From 1960 to 2020, the number of spring frost days of 60.3% stations across China showed a significantly decreasing trend −3.5 – 0 d (10 a)⁻¹, and the last frost date of 40% stations showed a significant advancing trend −4.3 – 0 d (10 a)⁻¹. Moreover, national-averaged anomalies for the number of spring frost days during 1960–2020 in China showed a significantly decreasing trend −1.3 d (10 a)⁻¹, while those for the last frost date showed a significantly advancing trend −1.7 d (10 a)⁻¹. 2) From 2021 to 2100, it is estimated that the number of spring frost days across China will decrease significantly −1.6 – 0 d (10 a)⁻¹, and the last frost day will advance significantly −1.4 – 0 d (10 a)⁻¹. In addition, national-averaged anomalies for the number of spring frost days in China will show a significantly decreasing trend at a rate of −0.8 d (10 a)⁻¹, and those for the last frost date will show a significantly advancing trend at a rate of −0.8 d (10 a)⁻¹.