Dynamical anomalies in terrestrial proxies of North Atlantic climate variability during the last 2 ka

Abstract

Recent work has provided ample evidence that nonlinear methods of time series analysis potentially allow for detecting periods of anomalous dynamics in paleoclimate proxy records that are otherwise hidden to classical statistical analysis. Following upon these ideas, in this study we systematically test a set of Late Holocene terrestrial paleoclimate records from Northern Europe for indications of intermittent periods of time-irreversibility during which the data are incompatible with a stationary linear-stochastic process. Our analysis reveals that the onsets of both the Medieval Climate Anomaly and the Little Ice Age, the end of the Roman Warm Period and the Late Antique Little Ice Age have been characterized by such dynamical anomalies. These findings may indicate qualitative changes in the dominant regime of inter-annual climate variability in terms of large-scale atmospheric circulation patterns, ocean-atmosphere interactions and external forcings affecting the climate of the North Atlantic region.

Xylem anatomical responses to climate variability in Himalayan birch trees at one of the world’s highest forest limit

“…Carla Vázquez-González (1)*, Vicente Rozas (2), Ricardo Alía (3), Luis Sampedro (1), Rafael Zas (1) (1) Misión Biológica de Galicia,Consejo Superior de Investigaciones Científicas,Spain. (2) Departmento de Ciencias Agroforestales, Universidad de Valladolid,Spain.…”

“…Stefan Kruse (1)*, Mareike Wieczorek (1,2), Laura S. Epp (1), Alexei Kolmogorov (3), Anatoly N. Nikolaev (3,4), Ingo Heinrich (2), Florian Jeltsch (5, 6, 7), Alex Gerdes (8), Luidmila A. Pestryakova 3, Romy Zibulski (1),Ulrike Herzschuh (1,9,10) (1) Polar Terrestrial Environmental Systems Research Group in Potsdam, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research,Germany,(2) GFZ German Research Centre for Geosciences,Telegrafenberg,Germany,(3) Institute of Natural Sciences, Russia,(4) Melnikov Institute of Permafrost SB RAS,Russia,(5) Department of Plant Ecology and Nature Conservation,Institute of Biochemistry and Biology,University of Potsdam,Germany,(6) Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Germany, (7) ZALF, Germany,(8) Institute of Physics and Astronomy,University of Potsdam,Germany,(9) Institute of Biology and Biochemistry,University of Potsdam,Germany,(10) Institute of Earth and Environmental Science, University of Potsdam, Germany *Correspondence: stefan.kruse@awi.de…”

“…Combining tree-ring growth and carbon isotope variability to infer the longterm drought responses of trees Matthias Saurer (1, 2)*, Galina Timofeeva (1,2,3), Kerstin Treydte (2), Harald Bugmann (3), Andreas Rigling (2), Marcus Schaub (2), Rolf Siegwolf (1,2) (1) Laboratory of Atmospheric Chemistry,Paul Scherrer Institut,Villigen,Switzerland,(2) Swiss Federal Institute for Forest,Snow and Landscape Research WSL,Birmensdorf,Switzerland,(3) Forest Ecology,Department of Environmental Systems Science,ETH Zürich,Zürich,Switzerland. *Correspondence: matthias.saurer@wsl.ch Increasing drought has been suspected to be a cause of tree decline in various regions. Stable carbon isotopes in tree-rings are sensitive to drought conditions and could therefore be useful for identifying such drought-effects.…”

Detecting dynamical anomalies in time series from different palaeoclimate proxy archives using windowed recurrence network analysis

“…The other vertical lines depict the approximate onset of the European Little Ice Age at 1400 AD, and the onset of the industrial age at 1850 AD. It should be noted that the timings and imprints of these episodes are known to exhibit substantial regional differences (Franke and Donner, 2017), thus, the reference lines are only for orientation. The model output time series do not show any areawise significant points even though the network transitivity of the tree ring model output varies similarly as the network transitivity of the temperature input with higher values corresponding to lower-dimensional dynamics during the Medieval Climate Anomaly and lower values corresponding to higher-dimensional dynamics during the Little Ice Age.…”

“…In Taken together, the previous findings should raise awareness in the context of future applications of wRNA to palaeoclimate proxy time series, suggesting that interpretations of results obtained for individual records only may not be sufficiently robust for drawing substantiated conclusions. From a practical perspective, this calls for combining different time series from different proxies and/or archives from the same region to obtain further climatological knowledge from such kind of analysis (Donges et al, 2015a;Franke and Donner, 2017).…”