Contrasting scaling properties of interglacial and glacial climates

• Published in: Nature communications 2016-03, Vol.7 (1), p.10951-10951, Article 10951
• Main Authors: Shao, Zhi-Gang, Ditlevsen, Peter D.
• Format: Article
• Language: English
• Subjects: 704/106/413; 704/2151/2809; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10951

Understanding natural climate variability is essential for assessments of climate change. This is reflected in the scaling properties of climate records. The scaling exponents of the interglacial and the glacial climates are fundamentally different. The Holocene record is monofractal, with a scaling exponent H ∼0.7. On the contrary, the glacial record is multifractal, with a significantly higher scaling exponent H ∼1.2, indicating a longer persistence time and stronger nonlinearities in the glacial climate. The glacial climate is dominated by the strong multi-millennial Dansgaard–Oeschger (DO) events influencing the long-time correlation. However, by separately analysing the last glacial maximum lacking DO events, here we find the same scaling for that period as for the full glacial period. The unbroken scaling thus indicates that the DO events are part of the natural variability and not externally triggered. At glacial time scales, there is a scale break to a trivial scaling, contrasting the DO events from the similarly saw-tooth-shaped glacial cycles. Natural climate variability and persistency are reflected in the scaling properties of climate records. Here, the authors show that the scaling properties of interglacial and glacial climates are distinctively different: The former is monofractal while the latter is multifractal with much longer range memory.