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Geomagnetic Field (Gmf) and Plant Evolution: Investigating the Effects of Gmf Reversal on Arabidopsis thaliana Development and Gene Expression

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Fall in Earth's magnetic field is erratic.

David Gubbins¹, Adrian L Jones, Christopher C Finlay

¹School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK. gubbins@earth.leeds.ac.uk

Science (New York, N.Y.)

|May 13, 2006

Summary

Earth's magnetic field strength remained steady from 1590 to 1840, unlike the later rapid decay. This stability suggests the dipole field was constant until the 19th century, with later changes originating in the Southern Hemisphere.

Area of Science:

Geophysics
Earth Science
Paleomagnetism

Background:

Earth's magnetic field has shown a significant decay rate of approximately 5% per century since 1840.
Directional measurements of the magnetic field predate intensity measurements by over 250 years.

Purpose of the Study:

To estimate the change in Earth's magnetic field strength from 1590 to 1840.
To investigate the origins of the magnetic field decay observed after 1840.

Main Methods:

Combined a global model of paleomagnetic directions with paleomagnetic intensity data.
Extrapolated magnetic field strength changes to the core surface.

Main Results:

Earth's magnetic field strength was nearly constant between 1590 and 1840 A.D.

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The later period of decay (post-1840) originated from patches of reverse magnetic flux in the Southern Hemisphere.

Directional data alone indicated the presence of these patches, but the pre-1840 model showed minimal evidence.

Conclusions:

The Earth's magnetic field maintained a steady dipole state up to 1840.
The observed decay in magnetic field strength began in the 19th century, driven by specific flux patches in the Southern Hemisphere.