The northeastern United States (NEUS) and the adjacent Northwest Atlantic Shelf (NWS) have emerged as warming hotspots, but the connection between them remains unexplored. Here we use gridded observational and reanalysis datasets to show that the twentieth-century surface air temperature increase along the coastal NEUS is exceptional on the continental and hemispheric scale and is induced by a combination of two factors: the sea surface temperature (SST) increase in the NWS associated with a weakening Atlantic Meridional Overturning Circulation (AMOC), and atmospheric circulation changes associated with a more persistent positive North Atlantic Oscillation. These connections are important because AMOC slowdown and NWS warming are projected to continue. A survey of climate model simulations indicates that realistic SST representation at high spatial resolution might be a minimum requirement to capture the observed pattern of coastal warming, suggesting that prior projection-based assessments may not have captured key features in this populous region.

美国东北部 (NEUS) 和邻近的西北大西洋大陆架 (NWS) 已成为变暖的热点，但它们之间的联系仍未探索。在这里，我们使用网格化的观测和再分析数据集来表明，20 世纪沿海岸 NEUS 的地表气温升高在大陆和半球尺度上是异常的，并且是由两个因素共同引起的： NWS 与减弱的大西洋经向翻转环流 (AMOC) 相关，以及与更持久的正北大西洋涛动相关的大气环流变化。这些联系很重要，因为预计 AMOC 放缓和 NWS 变暖将继续。