Global warming and its associated changes in the timing of seasonal progression may produce substantial ripple effects on the regional climate and ecosystem. This study analyzes the surface air temperature recorded during the period 1919–2017 at seven stations in the Republic of Korea to investigate the long-term changes at the beginning and ending of the summer season and their relationship with the warming trends of spring and autumn. The temperatures at the starting (June 1) and ending (August 31) dates of the past period (1919–1948) advanced by 13 days and delayed by 4 days, respectively, for the recent period (1988–2017). This asymmetric change was caused by continuous warming in May for the entire period of analysis and an abrupt warming in September in the recent decades. Different amplitudes of the expansion of the western North Pacific subtropical high in May and September are responsible for the asymmetric expansion of the summer season. The projections of surface warming for spring and autumn in Korea used the downscaled grid data of a regional climate model, which were obtained by the Representative Concentration Pathway 8.5 scenario of a general circulation model, and indicated a continuous positive trend until 2100. Larger interannual variability of blooming timing of early autumn flowers than that of late spring flowers may represent the response of the ecosystem to the seasonally asymmetric surface warming. Results suggest that the shift of seasons and associated warming trend have a disturbing effect on an ecosystem, and this trend will intensify in the future.

全球变暖及其与季节变化时间有关的变化可能会对区域气候和生态系统产生实质性的连锁反应。本研究分析了大韩民国七个站点在1919-2017年期间记录的地面气温，以调查夏季开始和结束时的长期变化及其与春季和秋季变暖趋势的关系。在最近时期（1988-2017年），过去一段时间（1919年至1948年）的开始（6月1日）和结束日期（8月31日）的温度分别提前了13天和推迟了4天。这种不对称的变化是由于整个分析期间5月份持续变暖和近几十年来9月份突然变暖引起的。5月和9月，北太平洋副热带高压西部的扩张幅度不同，这是夏季不对称扩张的原因。韩国春季和秋季的地表增暖预测使用了区域气候模型的缩小网格数据，该数据是通过一般循环模型的“代表性路径” 8.5情景获得的，并表明到2100年一直呈连续的正趋势。较大的年际变化性早秋花的开花时间比晚春花的开花时间的变化可能代表了生态系统对季节性不对称表面变暖的响应。结果表明，季节的变化和相关的变暖趋势会对生态系统产生不利影响，并且这种趋势将来还会加剧。