What would happen if the Earth's magnetic poles literally flipped upside down? If north was south and south was north? Would it just be our compasses going awry or would this result in a catastrophic end for the citizens of Planet Earth? Would a pole shift be the end of humanity?
It depends on who you ask.
For example, the UK Daily Mail describes this horrific scene:
This sounds like the plot for a disaster movie: an invisible magnetic force-field that defends life on Earth against killer rays from space goes awry. Blasts of radiation destroy our satellite communications and bring the world's electricity supplies crashing down.
Chaos reigns. Human cancer cases multiply as unshielded radiation from the sun devastates people's DNA. Billions of creatures the world over die because their ability to migrate becomes fatally confused by changes in our planet's magnetic field.
Ultimately, Earth's atmosphere itself could be blown away by fierce solar winds, as happened long ago to our sister planet Mars when its magnetic field dissipated.
But hold the popcorn. This is not a sci-fi movie. Leading scientists warn that this may really happen, because of an imminent revolution at the Earth's core. (source)
Meanwhile, Science 20 rebuts the doomsday scenario.
If we get a magnetic pole reversal, then from studies of previous reversals and modeling, the main risk is increased UV as a result of the ozone layer damaged by repeated solar storms. It would mean that you need to wear more sunblock cream on sunny days…
…The risks from solar storms are always present, whether it's a magnetic reversal or not. The main risk of a solar storm is of GPS satellites glitching for hours, recovering once it is over – and of power cuts. We used to think that the power cuts could be severe and cost getting on for a trillion dollars and risk power cut for months or longer.
However, the grid is more resilient than those early studies suggested. It is now thought to be similar to a major hurricane in effect, perhaps up to $100 billion in costs for the US and only local short-term power cuts…
…Some people get scared that it would lead to climate effects like ice melting at the poles, earthquakes, etc. This is a magnetic pole shift, not a geographical one. All that happens is that your compass starts to point in a different direction and eventually it points south instead of north. (source)
There are many signs that the poles are indeed going to flip.
When a pole shift occurs, it is a temporary phenomenon – it always shifts back. The problem is, we don't know precisely when this will happen. But the signs that it is imminent are present.
Geophysicist Daniel Baker of the University of Colorado at Boulder noted that over the past 200 years the planet's magnetic field has weakened by 15 percent, it can be a sign of the imminent geomagnetic inversion. (source)