Cosmic rays streamed through Earth’s atmosphere 41,000 years ago: New findings on the Laschamps excursion

Earth’s magnetic discipline protects us from the harmful radiation of space, however it’s not as everlasting as we would consider. Scientists on the European Geosciences Union Common Meeting present new details about an ‘tour’ 41,000 years in the past the place our planet’s magnetic discipline waned, and dangerous space rays bombarded the planet.

Earth’s magnetic discipline cocoons our planet from the onslaught of cosmic radiation streaming by space whereas additionally shielding us from charged particles hurled outward by the sun. However the geomagnetic discipline isn’t stationary. Not solely does magnetic north wobble, straying from true north (a geographically outlined location), however sometimes, it flips. Throughout these reversals, north turns into south, south turns into north, and within the course of, the depth of the magnetic discipline wanes.

However there’s additionally one thing referred to as magnetic discipline excursions, transient durations through which the depth of the magnetic discipline wanes and the dipole (or two magnetic poles) that we’re acquainted with can disappear, changed with a number of magnetic poles. The Laschamps tour that occurred round 41,000 years in the past is among the many greatest studied. It contains a low magnetic discipline depth that suggests much less safety for Earth’s floor from dangerous space rays. Durations of low magnetic discipline depth might correlate to main upheavals within the biosphere.

To see when cosmic rays had been closely bombarding Earth’s floor, scientists can measure cosmogenic radionuclides in cores from each ice and marine sediment. These particular isotopes are produced by the interplay between cosmic rays and Earth’s environment; they’re born of cosmic rays, therefore they’re cosmogenic.

Occasions of decrease paleomagnetic discipline depth—much less shielding—ought to correlate to increased charges of cosmogenic radionuclide manufacturing within the environment. Sanja Panovska, a researcher at GFZ Potsdam, Germany will current her findings concerning the relationship between paleomagnetic discipline depth and cosmogenic nuclides throughout the Laschamps tour, with a concentrate on space local weather, subsequent week throughout the European Geosciences Union (EGU) Common Meeting 2024.

Variations in cosmogenic radionuclides like beryllium-10 present an impartial proxy of how Earth’s paleomagnetic depth modified. Certainly, Panovska discovered that the common manufacturing charge of beryllium-10 throughout the Laschamps tour was two instances increased than present-day manufacturing, implying very low magnetic discipline depth and many cosmic rays reaching Earth’s environment.

To wring extra info from each cosmogenic radionuclide and paleomagnetic knowledge, Panovska reconstructed the geomagnetic discipline utilizing each datasets. Her reconstructions present that throughout the Laschamps tour, the magnetosphere shrank when the sector dramatically decreased, “thus decreasing the shielding of our planet,” she stated.

“Understanding these extreme events is necessary for his or her incidence sooner or later, space local weather predictions, and assessing the consequences on the atmosphere and on the Earth system.”