What happens if the magnetic field weakens

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Account icon An icon in the shape of a person's head and shoulders. It often indicates a user profile. Log out. US Markets Loading H M S In the news. Aylin Woodward. Earth's magnetic field protects the planet from deadly solar radiation, but it isn't static.

Satellites that keep tabs on the field show that one weak spot over the southern Atlantic Ocean has continuously grown over the last 50 years. This flip of the magnetic poles would have been devastating, creating extreme weather and possibly leading to the extinction of large mammals and the Neanderthals.

The magnetic poles wander and occasionally reverse around every , to , years, but we have little evidence on how this impacts our planet. Alan Cooper at the South Australian Museum in Adelaide and his colleagues have now provided some answers. The team calculated this using radiocarbon analysis of tree rings from an ancient, fossilised kauri tree Agathis australis preserved in northern New Zealand wetlands. When the magnetic field weakens, more cosmic rays enter the atmosphere and transform certain atoms into radioactive carbon, raising levels of this isotope.

Tarduno and his team suspect that the variation in the mantle under South Africa might have been the trigger point for magnetic field reversals in the past. The good news is that, even if the field is weakening, or preparing to flip, it's not going to disappear; there's no evidence that the magnetic field has ever gone away completely during a reversal. Even if the field reverses, "we'll still have some magnetic field present; it just is going to be a very weak magnetic field," Tarduno said.

What would this world with a minimal magnetic field look like? Well, your compass wouldn't work, for one thing. The northern and southern lights would be visible from lower latitudes, because these colorful shows are the result of the interaction between charged particles hurled from the sun in the solar wind and Earth's magnetosphere.

Currently, these auroras appear near the poles, following Earth's largely North-South magnetic field lines, but a weaker field would allow the particles to penetrate Earth's atmosphere, lighting up the sky closer to the equator. The conditions in the South Atlantic Anomaly for satellites might become common across the globe, which would cause technical glitches. Solar particles can ping electronics, disrupting bits of memory in what are called single-event upsets, or SEUs.

When solar particles interact with the charged layer of Earth's atmosphere called the ionosphere, they also knock electrons free from their molecular orbits.

These free electrons then interfere with the transmission of the high-frequency radio waves used for communication. Interactions between the solar wind and Earth's atmosphere can also break down the ozone layer over time, Tarduno said, which would raise humanity's collective ultraviolet radiation exposure and increase skin cancer risks. There is little evidence that past magnetic field variations have impacted life on Earth.

Still, the magnetic field has undoubtedly shaped Earth's surface, helping to keep the planet's fragile atmosphere from being blown into space by the relentless force of the solar wind, Archer told Live Science. A magnetic field is not crucial for having an atmosphere — Venus has no magnetic field and has a massive, if unwelcoming, atmosphere — but it certainly acts as an additional protective layer.

Mars, which used to have a magnetic field but lost it some 4 billion years ago, has had its atmosphere almost entirely stripped away. And if there were a way to give the moon an Earth-like atmosphere, the solar wind would whittle it to nothing in a mere century, Archer said. Originally published on Live Science.