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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Earth System Interactions and Information Transfer

Alternative title: Geosystemet: interaksjon og informasjon

Awarded: NOK 3.2 mill.

If we take seriously the concept of the "Earth system" as an evolving, complex system of coupled components (lithosphere-hydrosphere-atmosphere-biosphere), how do we test causal hypotheses using geological observations of its past behavior? In this project, we build on insights from dynamical systems theory and information theory to develop and test model-free techniques for detecting causal connections in geological records of Earth system history. A key result of this project is a new approach to estimating directional information flow (transfer entropy) between observed time series. This method can be used to text causal hypotheses in complex systems where mechanisms are poorly constrained or unknown, without recourse to modelling. Our approach makes the method more applicable to incomplete geological records with uncertainty. Our method paper will be published in 2018, and software made available on the project webpages: http://www.earthsystemevolution.com/ In the project period we have a completed several studies where we use this type of model-free methods to test causal hypotheses on deep time geological records. We have shown that global changes in the planktonic ecosystem have been dynamically linked to climate changes over the last 65 million years. This interdisciplinary work provides a new perspective on how we infer biotic response to environmental change in the deep past. We have also uncovered problems with the widespread practice of using geological formations to "correct" for sampling bias in the fossil record of biodiversity. These findings have important implications for how we reconstruct and interpret the history of life from the fossil record. We have also studied how insolation has influenced dynamical changes in global ice volume during glacial-interglacial cycles spanning the last 800 thousand years. We show that summer energy, or integrated summer insolation, at specific latitudinal bands, was a significant dynamical forcing of ice age climate variability. In addition to the classic Milankovitch forcing at high northern latitudes, we show that other latitudes may also have played an important dynamical role in global ice volume variability. Further results, methods and software will be made openly available on the project website: http://www.earthsystemevolution.com/

Earth scientists increasingly recognize our planet as a complex system of interactions among physical, chemical, and biological components. However, our ability to study Earth system interactions, based on the incompletely preserved rock record, is challe nged by the complexity of the system, as well as by limitations in both data and models. This project will combine innovative method development with analyses of geological records to confront these challenges. Information-theoretic techniques can quantif y the strength and directionality of coupling among components in a complex system, without making mechanistic assumptions. Such methods hold great promise for geological data analysis, but to fulfill this promise, several technical issues need to be addr essed, including protocols for data pre-processing and surrogate data methods, as well as open-source software implementation. Geological records of Earth system components stretch back more than 3 billion years, providing information on tectonics, biogeo chemical cycling, biotic macroevolution, and climate changes. This project will seek quantitative evidence for drive-response interactions among such records, on multiple time scales. With its data-driven, rigorous approach to testing causal hypotheses in deep time, this project will have potentially wide implications for our understanding of Earth system interactions, their importance in global environmental changes, and their role in the evolution of the biosphere.

Publications from Cristin

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FRINATEK-Fri prosj.st. mat.,naturv.,tek