Geomagnetism: From Alexander von Humboldt to Current Challenges

Abstract

The Earth's magnetic field shields our habitat against potentially harmful charged particles from outer space. Moreover, it is an important source of information about Earth's deep interior and geological history, both inaccessible to direct observations. Geomagnetism, the study of all aspects of the Earth's magneticfield, formed as a field of natural sciences in the early nineteenth century, largely under the influence of two prominent polymaths, Alexander von Humboldt and Carl Friedrich Gauss. On the occasion of the AGU 2019 centennial and Alexander von Humboldt's 250th anniversary, we link Humboldt's activities in geomagnetism with modern research in this domain and its challenges. Based on magnetic field observations during his scientific journeys, Alexander von Humboldt determined the increase of magnetic intensity with distance from the equator. He initiated coordinated observations across the globe and thus laid the foundation for international data exchange and collaboration. Observation is a prerequisite to a better understanding of the Earth's magnetic field with its various sources from the Earth's core, lithosphere, and electrical current systems outside the Earth, with a multitude of applications from navigation, exploration, natural hazard assessment, and study of Earth's evolution. A full understanding of the physical processes underlying the various geomagnetic field sources is mandatory to tackle the challenge of forecasting the future geomagnetic field evolution and to take advantage of the information that the geomagnetic field can provide about the Earth's history, geological and tectonic conditions and processes, and the near‐Earth's space environment.

Regional chronostratigraphy in the eastern Lesser Antilles quaternary fore-arc and accretionary wedge sediments: Relative paleointensity, oxygen isotopes and reversals

“…This non-destructive approach enables correlation of multiple cores and stratigraphic events for entire regions. While paleomagnetism has been widely used to understand past geomagnetic field fluctuations, increasing global data coverage remains a longterm challenge for understanding geomagnetic field dynamics (Korte and Mandea, 2019), and for chronostratigraphic purposes.…”

A Review of Black Skin Research: Gloger Rule/Theory Dead or Alive?

“…While La Condamine (1745) and Humboldt (1808Humboldt ( , 1831 made seminal measurements and observations of the equator and latitudinal differences, they never defined the concepts heat, radiation, or sunshine as limited to a specific location/weather much less Sub-Saharan Africa. Because the earth is (viewed as) a sphere, the notion equator was thus understood as the dividing line at which geomagnetic force increases the most as one moves from the tropics toward that line (Korte & Mandea, 2019). No skin color was implied or predicted.…”

“…Moreover, in all species, black color crosscuts latitude, weather, and body parts. Humboldt did not use the concept Caucasian although he was a student of Blumenbach at the University of Göttingen (Korte & Mandea, 2019;Wulf, 2016). Perhaps most importantly, despite the fact that Humboldt invented and used measurement instruments for latitudes and altitudes and that he was an avid traveler himself, he did not conceive or use a global map for the skin color of animals, plants, or humans.…”

Effects of the Laschamps Excursion on Geomagnetic Cutoff Rigidities

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The geomagnetic core field is generated in the Earth's outer core and it reaches out several Earth radii into space, protecting our planet from solar and cosmic energetic particles (e.g., Jackson & Finlay, 2015;Korte & Mandea, 2019). The geomagnetic field is not static but constantly changing.

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