Earth’s magnetic field shields us from damaging solar radiation, but its strength and ability to protect us is variable. Scientists uncovered details about a geomagnetic spike that happened around 1,000 BC that could alter our understanding of the magnetic field and the planet’s interior – and they’re exploring how a similar event might impact us if it occurred today.
Scientists identified 1,000 BC’s geomagnetic spike after investigating copper from slag heaps in Jordan and Israel. They began to explore what Earth’s magnetic field might have been like way back then, and found something surprising: the copper recorded Earth’s magnetic field strength rising and then falling by more than 100 percent in 30 years.
That research was published in 2010, but University of Leeds lecturer Christopher Davies, in a piece for The Conversation, highlighted other discoveries since pointing to high field strengths around the same time in Turkey, China, and Georgia. Meanwhile, field strengths in Egypt, India, and Cyprus were normal – so the spike may have been only around 2,000 kilometers, or around 1,243 miles, wide. Davies wrote, “Such a rapid change over such a small area marks out the geomagnetic spike as one of the most extreme variations of Earth’s magnetic field ever recorded.”
Researchers aren’t quite sure what caused the spike, but the flow of iron in the core could have played a role. That said, explaining the changes that came with the geomagnetic spike requires flows five to 10 times greater than what we observe today. “The prospect that the iron core could flow faster and change more suddenly than previously thought, together with the possibility that even more extreme spike-like events occurred in the past, is challenging some conventional views on the dynamics of Earth’s core,” Davies said.
Spikes must be accompanied by weak spots, which is where geomagnetic storms tend to be prevalent. So if a spike happened today, part of the planet could see power outages or satellite disruption because of a geomagnetic storm. But Davies said it’s hard to say if another spike will happen – until recently, the Jordan spike was the only such event scientists had observed. There’s now some evidence a spike also occurred in Texas around 1,000 BC.
Via The Conversation