Research
GERACLE stands for ‘Geomagnetic Excursions and Reversals: Establishing their Atmospheric and Climatic Effects’. The aim of the project is to understand the consequences of polarity reversals of the Earth's magnetic field for the atmosphere and our habitat. The Earth's magnetic field provides a natural protective shield against dangerous particles from the solar wind and cosmic radiation. When polarity reversals occur, the field weakens and changes its shape – with sometimes significant consequences for life on Earth. The project is focussing on the entire Sun-Earth system in order to investigate their interactions under unusual magnetic field conditions and a wide range of solar activity and climatic conditions.
Background: Change and role of the Earth's magnetic field
The Earth's magnetic field acts as a protective shield for our planet against solar wind and cosmic radiation, which determine the so-called space weather. The Earth's magnetic field originates in its liquid outer core and therefore varies slightly, but continually, in strength and direction. In the course of the Earth's history, however, the magnetic field has also completely reversed polarity several times - permanently or briefly, in the form of so-called reversals and polarity excursions. These extreme field changes are accompanied by a drastic decrease in the magnetic field strength, but also by an increase in the complexity of the field geometry. For example, more than two poles can form. This significantly weakens and changes the protective shield.
The last permanent field reversal, known as the Matuyama-Brunhes, took place 780,000 years ago; the last short-term polarity reversal occurred 41,000 years ago during the so-called Laschamps excursion. However, after around 1500 turbulent years, the magnetic field then returned to its original, comparatively stable polarity. Such events will occur again in the future, even if not in the near future.
The ERC project GERACLE in detail
The ERC project GERACLE investigates the effects of past and future reversals and polarity swings of the Earth's magnetic field on our habitat.
Previous studies, which made simplistic assumptions and analysed correlations rather than the full physical relationships, are inconclusive. They show a broad spectrum of possible effects: from ‘no influence of the field polarity on our habitat’ to strong climatic consequences and resulting mass extinctions of living organisms.
For the first time, GERACLE will comprehensively analyse the complex physical relationships in the entire Sun-Earth system during very different states of the Earth's magnetic field. It will consider the magnetosphere, but also the Sun and the climate, which is strongly influenced by other factors.
The GERACLE management team consists of four interdisciplinary members. For the first time, GERACLE brings together expertise on the long-term development of the Earth's magnetic field, the magnetosphere, solar activity and solar-terrestrial relationships as well as radiation processes in the Earth's environment, and on atmospheric processes and Earth system modelling.
Key objectives of the project
The main goal of GERACLE is to develop a unified physical framework for the Sun-Earth system considering unusual, but realistic geomagnetic field configurations. This will allow to analyse magnetospheric and atmospheric processes under changing geomagnetic field, climate and solar conditions. The results of the project will not only provide information about specific events in the Earth's history, but also important insights into solar-terrestrial relationships under a significantly changing geomagnetic field and the assessment of future space weather hazards. In particular, it aims to answer the long-standing question of how serious the effects of geomagnetic reversals and polarity excursions can be on the Earth's environment.
The contributions of the individual partner institutions
The group at the GFZ led by Dr. Monika Korte will lead the project. With its many years of expertise in the global reconstruction of past magnetic field development, they will be responsible for the most accurate possible characterisation of the magnetic field during the polarity events to be investigated. To this end, new palaeomagnetic data from sediment cores will be measured in the laboratory and used together with existing data to calculate global models. Investigations into data quality and possible environmental influences on the magnetic signal play an important role here. The findings will also be used to estimate the magnetic field configuration during a possible future polarity reversal.
The group at the University of Helsinki led by Prof. Emilia Kilpua will provide the expertise on solar eruptions, solar wind and radiation belts to the Synergy project. Through GERACLE the researchers expect to achieve several solar physics breakthroughs including a novel understanding of solar and heliospheric structures from grand solar maxima to minimum conditions.
The team at the University of Oulu led by Prof. Ilya Usoskin will provide expertise on the radiation fields in complex magnetospheric conditions during the non-standard geomagnetic configuration. Through GERACLE the researchers expect to achieve several breakthroughs in geophysics, for example, the (non)existence of radiation belts and patterns of the radiation field under unusual geomagnetic field conditions.
The team at BOKU University led by Prof. Harald Rieder will provide the expertise on chemistry-climate connections and earth-system modeling to the Synergy project. Through GERACLE the researchers expect to provide pioneering insights into changes in atmospheric composition during unusual geomagnetic field conditions and the related consequences for the exposure to elevated UV radiation at the ground, as well as changes in atmospheric circulation and potentially even regional climate.