Climate entropy production recorded in a deep Antarctic ice core

TL;DR

This study applies information theory, specifically weighted permutation entropy, to analyze Antarctic ice core data, revealing new insights into past climate variability and potential geothermal influences, demonstrating the method's value in paleoclimatology.

Contribution

It introduces the use of weighted permutation entropy to extract meaningful information from ice core records, highlighting its ability to detect climate signatures and data effects.

Findings

WPE correlates with ice accumulation rates

Detects possible geothermal heating signatures

Reveals subtle climate event signals

Abstract

Paleoclimate records are extremely rich sources of information about the past history of the Earth system. Information theory, the branch of mathematics capable of quantifying the degree to which the present is informed by the past, provides a new means for studying these records. Here, we demonstrate that estimates of the Shannon entropy rate of the water-isotope data from the West Antarctica Ice Sheet (WAIS) Divide ice core, calculated using weighted permutation entropy (WPE), can bring out valuable new information from this record. We find that WPE correlates with accumulation, reveals possible signatures of geothermal heating at the base of the core, and clearly brings out laboratory and data-processing effects that are difficult to see in the raw data. For example, the signatures of Dansgaard-Oeschger events in the information record are small, suggesting that these abrupt warming events may not represent significant changes in the climate system dynamics. While the potential power of information theory in paleoclimatology problems is significant, the associated methods require careful handling and well-dated, high-resolution data. The WAIS Divide ice core is the first such record that can support this kind of analysis. As more high-resolution records become available, information theory will likely become a common forensic tool in climate science.