The oscillatory behaviour of the climate system on decadal timescales before the instrumental record is hard to quantify. However, knowledge of this variability is important for putting current changes in context and for supporting reliable future predictions. Here we investigate the recurrent component of Holocene climate variability in the North Atlantic sector from 10,500 to 2,000 years ago by conducting a frequency analysis of both an annually laminated climate record from a lake in England and outputs from a long transient simulation of the Atlantic meridional overturning circulation. We find consistent decadal variability over the past 6,700 years and before 8,500 years before present, probably reflecting predominance of solar and ocean forcings. Between these dates, climate variability was dampened on decadal timescales. Our results suggest that meltwater discharge into the North Atlantic and the subsequent hydrographic changes, from the opening of the Hudson Bay until the final collapse of the Laurentide Ice Sheet, disrupted the decadal cyclic signals for more than a millennium. Given the current acceleration of the Greenland Ice Sheet melting in response to global warming, this study provides long-term evidence of potential challenges predicting future patterns of the climate system.

在仪器记录之前，气候系统在年代际时间尺度上的振荡行为很难量化。然而，了解这种可变性对于将当前变化置于背景中以及支持可靠的未来预测非常重要。在这里，我们通过对英格兰一个湖泊的年度层叠气候记录和大西洋经向翻转的长期瞬态模拟的输出进行频率分析，调查了 10,500 到 2,000 年前北大西洋地区全新世气候变率的经常性组成部分循环。我们发现过去 6,700 年和 8,500 年前的年代际变率一致，可能反映了太阳和海洋强迫的优势。在这些日期之间，气候变率在年代际时间尺度上受到抑制。我们的研究结果表明，融水排入北大西洋以及随后的水文变化，从哈德逊湾的开放到劳伦蒂德冰原的最终崩塌，扰乱了年代际周期信号达一千年以上。鉴于目前格陵兰冰盖因全球变暖而加速融化，这项研究提供了预测气候系统未来模式的潜在挑战的长期证据。