What If Earth's Magnetic Field Disappeared?

Pedro_P

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It wouldn't be great, but it wouldn't be like a disaster movie, either.

Around Earth, an invisible magnetic field traps electrons and other charged particles.(Image: © NASA's Goddard Space Flight Center)
▼ Extending from Earth like invisible spaghetti is the planet's magnetic field. Created by the churn of Earth's core, this field is important for everyday life: It shields the planet from solar particles, it provides a basis for navigation and it might have played an important role in the evolution of life on Earth.
But what would happen if Earth's magnetic field disappeared tomorrow? A larger number of charged solar particles would bombard the planet, putting power grids and satellites on the fritz and increasing human exposure to higher levels of cancer-causing ultraviolet radiation. In other words, a missing magnetic field would have consequences that would be problematic but not necessarily apocalyptic, at least in the short term.
And that's good news, because for more than a century, it's been weakening. Even now, there are especially flimsy spots, like the South Atlantic Anomaly in the Southern Hemisphere, which create technical problems for low-orbiting satellites.
The first thing to understand about the magnetic field is that, even if it weakens, it's not going to disappear — at least, not for billions of years. Earth owes its magnetic field to its molten outer core, which is made mostly of iron and nickel. The churning outer core is powered by the convection of heat released as the inner core grows and solidifies, said John Tarduno, a geophysicist at the University of Rochester. (The inner core grows by about a millimeter per year.)
This magnetic-field engine, known as a dynamo, has been chugging along for billions of years. Scientists think that the current core arrangement may have settled into place about 1.5 billion years ago, according to 2015  researchthat found a leap in the magnetic field's strength around then. But Tarduno and his team have found evidence for a magnetic field on Earth in the planet's oldest minerals, zircons, dating back 4.2 billion years, suggesting that activity in the core has been creating magnetism for a very long time.
It isn't clear why the dynamo got started, Tarduno told Live Science, though it's possible that the enormous planetary impact that created the moon might have been the key driver. This impact, which occurred perhaps 100 million years after Earth came  together, could have shaken up any stratification, or layering, of materials in Earth's core: Imagine shaking up a bottle of oil and water on a planetary scale. This disruption could have promoted the convection that still drives Earth's dynamo today.
Eventually, the inner core will probably grow large enough that convection in the outer core is no longer efficient, and the magnetic field will fail. But that scenario is so far off that it's not worth losing much sleep over.
"We're talking billions of years," Tarduno said.
Weakening magnetic field (▪ ▪ ▪)

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asr335704

It is going to take lot of years for magnetic field to completely disappear. So we would still be able to survive even though Earth's magnetic field gradually disappears in coming million years.

chanakyakripa

When author himself tells the phenomenon to happen will take billions of years, there's no point of speculating. Whether human beings will survive such a time scale can be a better point of speculation, looking at the self destructive mode we are in currently.