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

TL;DR

This study uses nonlinear time series analysis to detect periods of anomalous, non-stationary climate dynamics in North Atlantic paleoclimate records over the last 2,000 years, revealing key climate regime shifts.

Contribution

It introduces a systematic approach to identify dynamical anomalies in paleoclimate proxies during major climate events in the Late Holocene.

Findings

Detected dynamical anomalies during the Medieval Climate Anomaly and Little Ice Age.

Identified regime shifts at the end of the Roman Warm Period and the Late Antique Little Ice Age.

Indicated changes in atmospheric circulation and ocean-atmosphere interactions.

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 statis- tical 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 circula- tion patterns, ocean-atmosphere interactions and external forcings affecting the climate of the North Atlantic region.