Quantification and interpretation of the climate variability record

TL;DR

This paper updates and interprets the spectral view of climate variability, integrating recent observations and methods to better understand the complex interactions between internal and forced climate fluctuations across timescales.

Contribution

It revises the classic Mitchell (1976) diagram with new data and methodologies, enhancing the understanding of climate variability and its causal links.

Findings

Updated spectral diagram with extended observations

New methodological developments for spectral analysis

Challenges identified for detailed quantification of climate variability

Abstract

The spectral view of variability is a compelling and adaptable tool for understanding variability of the climate. In Mitchell (1976) seminal paper, it was used to express, on one graph with log scales, a very wide range of climate variations from millions of years to days. The spectral approach is particularly useful for suggesting causal links between forcing variability and climate response variability. However, a substantial degree of variability is intrinsic and the Earth system may respond to external forcing in a complex manner. There has been an enormous amount of work on understanding climate variability over the last decades. Hence in this paper, we address the question: Can we (after 40 years) update the Mitchell (1976) diagram and provide it with a better interpretation? By reviewing both the extended observations available for such a diagram and new methodological developments in the study of the interaction between internal and forced variability over a wide range of timescales, we give a positive answer to this question. In addition, we review alternative approaches to the spectral decomposition and pose some challenges for a more detailed quantification of climate variability.