Will Earth's Magnetic Poles Flip and What Does it Mean?

The conditions that allow life on earth are a strange dichotomy where life seems both resilient and tenacious yet lives on a fragile, incredible world that against all odds has been a paragon of stability since life first arose. This stability has been key to the rise of humans and one of the most important aspects of that stability is the existence of earth's protective magnetic field.

Earth's magnetic field bathes and protects the surface of our planet from charged particles streaming off the sun. Generated in the earth's molten core by convecting currents, the field is not something we can take for granted. It changes continuously, but not all planets have magnetic fields and certain aspects of our own can change on a dime. One such aspect are the earth's magnetic poles which in the past have reversed multiple times, typically several times per million years. They will do so again in the future, so the natural question is when will the next shift occur and what effect will it have on life on earth?

One thing it won't do is outright shut down, if it did that life on earth would have gone extinct long before microbes would have had time to evolve into complex life. But, if past events are any indicator, it will become weaker for a time and become more complex potentially losing up to 90% of its strength. We might also see, for a short time, multiple north and south poles all over the earth.
There are also different classes of pole reversals. One are incomplete reversals known as excursions where the magnetic poles wander from their normal positions for a time or reverse temporarily. One such reversal, the Laschamp event, did just that about 41,000 years ago, saw a 250-year period where the poles reversed completely but reverted back with the whole field returning back to normal within a thousand year period. The other class are full reversals where the poles shift completely and stay that way until the next event occurs hundreds of thousands of years later.

But as far as life is concerned, the changes that will happen will allow more radiation from the sun to reach the surface. This isn't as bad as it seems for us, the most vulnerable thing is our technology. As we're currently set up, it would wreak havoc on our satellites and power grid and our civilization in general. But we're already at risk of that from powerful solar flares which present a much more urgent threat but that's a topic for another video.

It's worth noting however that life itself has survived many of these reversals, so it must not be that bad as far as being alive is concerned. How it affects our species however is different. We are the top of the chain as far as evolution is concerned and that could easily make us more prepared for it due to our intelligence and ingenuity, or wide open for a collapse of technology and even an extinction. It's hard to say, but we did survive the Laschamp event early in our history so I suspect we would survive a full reversal but our technological civilization, at least as it is now, would not.

The collapse of civilization aside, where I would wonder are the species on earth that make use of magnetoreception. This is thought to include everything from migratory birds, bacteria, mammals, and potentially even us though that is still unproven. These organisms, to varying degrees, sense earth's magnetic field and use it for navigation while they migrate or find their way home. If you change the magnetic map for them, do we end up with confused geese heading towards the arctic and salmon beaching themselves by the millions?

But how close are we to the next reversal? Well, studies of the earth's magnetic field reveal that it's already decreasing in strength at a rate of about 5 percent per century. This would suggest that we're within 2000 years of the next one. But that's about all we can say as the inner workings of the circulating molten iron outer core generating the field are still poorly understood.

But, despite the outer core being located thousands of miles beneath us and notoriously difficult to study, we learn more each year, so some day it may be the case where predicting earth's inner weather is done as easily with as much accuracy as we do with its atmospheric weather ... hey, wait.