New research from the University of Rochester in New York reveals that life on Earth had a lucky break 565 million years ago when the collapse of Earth's magnetic field was impeded by the ready solidification of Earth's inner core.
The slow collapse of Geodynamic
A new study published in the journal Natural Geosciences provides strong evidence that the Earth was about to suffer a catastrophic collapse of its magnetic field about 565 million years ago.
Looking at crystals found near Quebec, Canada, dating to about half a billion years ago, chief researcher Richard Bono found strong evidence that the Earth's magnetic field was about 10 times weaker than it is today and getting weaker.
The grids on the crystals – which are sensitive to changes in Earth's magnetism – showed that the system went through a period of weakness that lasted for about 75,000 years, with its weakest point appearing 565 million years ago.
This was far more than it would have been if the weakness had been the result of an imminent change of direction or pole inversion, which occurred regularly in the past. The only explanation would have been the imminent collapse of the geodynamic, the convection currents of the liquid outer core of the Earth responsible for the generation of the magnetic field.
"Liquid iron in the outer core coexists, carrying with it magnetic field lines that twist, continuously regenerating the field. Without convection, there would be no central magnetic field, "said study co-author John Tarduno.
The Earth's magnetic field is not just about its compass
The role that this shield around the Earth plays, for the most part, is not appreciated by the general public, but it is a silent guardian over all life on Earth.
Without it, the sun's solar winds, charged particles that are expelled by the sun at millions of miles per hour, reach our atmosphere without interference. Over time, this would have a similar effect on the atmosphere, as well as the weathering effect of desert sand on desert monuments. Over time, the paint is removed, the features are flattened and, given the time required, the whole statue would be worn down to nothing.
And we do not have to speculate on what it would be like, all we have to do is look at the arid landscape of Mars to understand how the Earth might look without a strong magnetic field.
Saved on Iron-Nickel of Time
By the time the Earth's magnetic field was weaker, life on Earth had a stroke of luck. The internal iron-nickel nucleus of the planet began to solidify.
It is believed that originally it was totally liquid as the outer core, eventually the pressure of such a material overload would slowly force the liquid into an effectively solid state while the surface temperature of that mass would reach just over 5,400 degrees Celsius.
Over time, the inner core would grow as the iron-nickel alloy of the outer core would solidify under pressure to add its mass to the inner core. This process of solidification, or "nucleation", provided the essential impetus in the energy that the geodynamic disappeared.
"As the Earth evolved," Tarduno said, "the energy to drive convection has gradually diminished to a critical point 565 million years ago, marked by the extremely low intensity of the magnetic field. The growth in the inner core provided a new source to boost convection and the geodynamic. "
Thanks to the restoration of Earth's magnetic field, life was able to continue and thrive, with the Cambrian explosion, the massive growth of biodiversity responsible for animal life, not long after things began to turn 565 million years ago.