Feedback of tropics–Arctic linkages to Northern Hemisphere warming might be modulated by ENSO diversity in the future

The climate coupling between the tropics and the Arctic not only modulates Arctic amplification but may also induces substantial feedbacks to the Northern Hemisphere and even the global climate. Here, we use climate models that reproduce the historical winter tropics–Arctic temperature relationship to project future changes in tropics–Arctic temperature coupling for the period 2050–2099. Our results identify two dominant modes: a dipole-type (Group A) and a pan-regional coherent type (Group B) mode, based on the contribution of models to the leading empirical orthogonal function mode. Notably, Group A models exhibit weaker Northern Hemisphere warming than Group B. At the end of the 21st century (2095–2099), mean surface atmospheric temperatures under Group B exceed those under Group A by 1.03°C in the tropics, 1.88°C in the midlatitudes, and 5.07°C in the Arctic. Further analysis reveals that Group A features stronger SST variability in the tropical eastern Pacific region, indicating more pronounced eastern Pacific–type ENSO events. Against this background of enhanced variability, Group A is projected to experience more frequent extreme La Niña events, leading to smaller eastern Pacific SST warming and, via Pacific–North American (PNA) teleconnections, a weaker Arctic warming. Conversely, Group B is projected to exhibit more extreme El Niño events, greater eastern Pacific SST increases, and a stronger Arctic warming trend. 热带-北极之间的气候关联不仅影响北极放大效应, 还可能对北半球乃至全球气候产生重要的反馈作用.本文基于在历史时期能够较好再现冬季热带-北极温度关系的气候模式, 对未来 (2050–2099年) 热带与北极温度之间的关系进行了预估.结果表明, 未来的热带-北极关系主要表现为两种模态:偶极型 (A组模式) 和全区一致型 (B组模式) .值得注意的是, A组模式所模拟的北半球变暖幅度小于B组模式.在21世纪末最后五年, B组模式在热带,中纬度和北极地区的平均温度分别比A组模式高1.03°C,1.88°C和5.07°C.进一步分析表明, A组模式在热带东太平洋区域呈现出更强的海表温度变率, 意味着更显著的EP型ENSO活动.在这种增强的变率背景下, A组模式预估出更频繁的极端La Niña事件, 导致东太平洋海温升幅较小, 进而通过太平洋-北美型遥相关影响北极, 使得北极地区增温趋势较弱.相反, B组模式则倾向于发生更多极端El Niño事件, 东太平洋海温上升更为明显, 最终导致北极地区呈现出更强的增温趋势.