Hébert R, Herzschuh U, Laepple T
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany.
Institute of Geosciences, University of Potsdam, Potsdam, Germany.
Nat Geosci. 2022 Nov;15(11):899-905. doi: 10.1038/s41561-022-01056-4. Epub 2022 Oct 31.
Variations in regional temperature have widespread implications for society, but our understanding of the amplitude and origin of long-term natural variability is insufficient for accurate regional projections. This is especially the case for terrestrial temperature variability, which is currently thought to be weak over long timescales. By performing spectral analysis on climate reconstructions, produced using sedimentary pollen records from the Northern Hemisphere over the last 8,000 years, coupled with instrumental data, we provide a comprehensive estimate of regional temperature variability from annual to millennial timescales. We show that short-term random variations are overprinted by strong ocean-driven climate variability on multi-decadal and longer timescales. This may cause substantial and potentially unpredictable regional climatic shifts in the coming century, in contrast to the relatively muted and homogeneous warming projected by climate models. Due to the marine influence, regions characterized by stable oceanic climate at sub-decadal timescales experience stronger long-term variability, and continental regions with higher sub-decadal variability show weaker long-term variability. This fundamental relationship between the timescales provides a unique insight into the emergence of a marine-driven low-frequency regime governing terrestrial climate variability and sets the basis to project the amplitude of temperature fluctuations on multi-decadal timescales and longer.
区域气温变化对社会有着广泛影响，但我们对长期自然变率的幅度和来源的理解还不足以进行准确的区域预测。陆地气温变化尤其如此，目前认为其在长时间尺度上较为微弱。通过对利用北半球过去8000年沉积花粉记录以及仪器数据生成的气候重建结果进行频谱分析，我们对从年际到千年时间尺度的区域气温变化进行了全面估计。我们发现，在数十年及更长时间尺度上，短期随机变化被强烈的海洋驱动气候变率所叠加。这可能在未来世纪导致显著且可能无法预测的区域气候变化，这与气候模型预测的相对温和且均匀的变暖情况形成对比。由于海洋的影响，在年代际以下时间尺度上具有稳定海洋气候特征的区域经历更强的长期变率，而年代际以下变率较高的大陆区域则显示出较弱的长期变率。时间尺度之间的这种基本关系为理解控制陆地气候变率的海洋驱动低频状态的出现提供了独特视角，并为预测数十年及更长时间尺度上的气温波动幅度奠定了基础。
