By Xavier Lam
Here’s a fun fact: The Earth’s magnetic poles have switched places many times before. This means that if you looked at a compass, North would be South and vice versa.
The Earth’s Magnetic Field
Geophysicists at NASA think that the reason Earth has a magnetic field is because its solid iron core is surrounded by hot, liquid iron. This ocean of iron, is an electrically conducting fluid in constant motion. This liquid outer core, also has whirlpools powered by the Coriolis forces of Earth’s rotation. These complex motions generate our planet’s magnetism through a process called the dynamo effect. This magnetic field is unlike a regular magnet you would find on a fridge. Its polarity is not constant, and shifts around frequently.
When will the next switch be?
There have been 183 reversals over the last 83 million years, but for the past 20 million years, the poles have been switching around a pattern of every 200,000 to 300,000 years. A previous unsuccessful attempt to switch poles was around 40,000 years ago, and the previous successful one was about 780,000 years ago. It is possible that we could be overdue for a reversal sometime soon.
The Impact?
The switch could possibly affect any animal species such as pigeons, which have an ability that enables them to sense the Earth’s magnetic field. They may use this to assist in long-distance navigation during migration. Though it is still undeterminable what impact a reversal might have on such species.
Some scientists hypothesize that the reversal will have a doomsday effect on Earth, where the magnetic field will disappear and allow damaging solar radiation to wreak havoc on the earth, causing mass extinction or cataclysmic volcanism.
However, NASA disagrees with these doomsday hypotheses. They state that a weaker magnetic field would only allow small increase in solar radiation on Earth but nothing deadly. They state that the thick atmosphere would also offer protection against the sun’s incoming particles.
A more interesting effect that the switch would lead to is a beautiful display of aurora in the lower latitudes.
Final Thoughts
I think this is a great topic because there is still much uncertainty to the eventual impact. With the added threat of climate change, I wonder if the ozone layer will be so damaged that the doomsday theories will be plausible. What is your opinion on this topic? Do you think the doomsday hypotheses are believable?
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