The jet stream is an important dynamic driver of climate variability in the Northern Hemisphere mid-latitudes^1,2,3. Modern variability in the position of summer jet stream latitude in the North Atlantic–European sector (EU JSL) promotes dipole patterns in air pressure, temperature, precipitation and drought between northwestern and southeastern Europe. EU JSL variability and its impacts on regional climatic extremes and societal events are poorly understood, particularly before anthropogenic warming. Based on three temperature-sensitive European tree-ring records, we develop a reconstruction of interannual summer EU JSL variability over the period 1300–2004 ce (R² = 38.5%) and compare it to independent historical documented climatic and societal records, such as grape harvest, grain prices, plagues and human mortality. Here we show contrasting summer climate extremes associated with EU JSL variability back to 1300 ce as well as biophysical, economic and human demographic impacts, including wildfires and epidemics. In light of projections for altered jet stream behaviour and intensified climate extremes, our findings underscore the importance of considering EU JSL variability when evaluating amplified future climate risk.

急流是北半球中纬度地区气候变率的重要动态驱动因素^1,2,3。北大西洋-欧洲地区 （EU JSL） 夏季急流纬度位置的现代变化促进了西北欧和东南欧之间气压、温度、降水和干旱的偶极子模式。欧盟 JSL 变率及其对区域极端气候和社会事件的影响知之甚少，尤其是在人为变暖之前。基于三个对温度敏感的欧洲树木年轮记录，我们重建了公元 1300-2004 年期间夏季 EU JSL 的年际变化 （R² = 38.5%），并将其与独立的历史记录气候和社会记录进行比较，例如葡萄收获、谷物价格、瘟疫和人类死亡率。在这里，我们展示了与公元 1300 年以来欧盟 JSL 变化相关的对比夏季极端气候，以及生物物理、经济和人类人口影响，包括野火和流行病。鉴于对急流行为改变和极端气候加剧的预测，我们的研究结果强调了在评估放大的未来气候风险时考虑欧盟 JSL 可变性的重要性。