As a genre, the “disaster movie” is a just about as old as cinema itself. The movies themselves seem to get ever more implausible with the passing of each year, with every type of disaster getting explored, and with the next threat to humankind needing to be a tiny bit madder than the last. Remember all those films from the 1990s and 2000s when the world was going to end? Deep Impact, Armageddon and The Day After Tomorrow in particular spring to mind.

But can you remember Absolute Zero or Polar Storm? Me neither. Both dealt with the effects of a change in the Earth’s magnetic field – with typically outlandish consequences. However, it would seem that they might have been onto something judging by an interesting news story this week (albeit there is no current indication that Florida is about to enter an ice age).

It would seem there have been odd goings on with the Earth’s magnetic field in the South Atlantic. Since 1970 the strength of the magnetic field in this region has dropped by 8%. This in turn has been creating problems for satellites flying overhead, some of which have been malfunctioning because they rely on the Earth’s magnetic field to work as intended.

Now, I know next to nothing about satellites, but it is pretty astonishing to think that some geological happenings taking place within the core of the Earth are enough to break some spacecraft flying overhead.

It was enough to prompt me to find out more. This led me to discover that, apparently, the Earth’s magnetic field has lost around 10% of its overall strength over the past two centuries.

10%! As if dealing with Covid-19 wasn’t enough, it now seems our compasses are about to stop working too!

As ever, the headline writers are quite possibly exaggerating about what is going on here.

First of all, let’s deal with the purpose of the magnetic field. Yes, it helps us navigate around the globe by telling us where the magnetic north is, which itself means that we can plot where everywhere else is on Earth in relation to this point. This is clearly very important for all manner of reasons. GPS wouldn’t work without this reference point, for example, which would make global navigation less accurate, and which itself would carry some potentially serious economic implications. Nobody wants a cargo ship going the wrong way due to human error, and thus causing expensive disruptions to a global supply chain.

However, perhaps more importantly for life on Earth, the magnetic field dictates the presence of the ‘magnetosphere’ around our planet which helps repel deadly radiation particles emitted from the sun. I’d place this at the top of my ‘magnetic field importance list’, well ahead of my wristwatch being able to track my latest slow run for uploading to Strava.

Is there any indication at all that the magnetosphere is suddenly going to vanish? No. While some changes to the strength of the magnetic field might have been detected, there is zero indication that deadly radiation is going to stream through the atmosphere and kill us all.

I do find the idea of the impact on satellites intriguing, though, and mainly because of the size of the numbers involved. There are around 5,000 satellites currently orbiting Earth, not counting the debris that has ended up in orbit, of course, over the last seventy years. Just think of all the money spent on getting those satellites up there. Not all satellites are created equal, but it would seem that the cost of building one could be around the $290 million mark (various websites disagree on the cost, and this figure appears to be somewhere in the middle).

Using this number – and using back of a fag packet maths– then we might estimate that there is $1.45 trillion whizzing around our planet in hardware. And that’s before counting the cost of getting it there in the first place – somewhere between $50-400 million per satellite, depending on the payload – as well as the cost of ongoing maintenance once it is up there.

These are mind-boggling sums, of course, and it seems inconceivable that so much money would be spent on thousands of machines that are capable of breaking down because of things occurring thousands of miles deep within the Earth.

The fact that this is true, and is actually happening… Well, the mysteries of space and our planet will never cease to be a cause of fascination to me. Nor will our collective ability to spend lots of money on things that don’t work properly. Most importantly, for now, I’m glad we’re not in disaster movie territory just yet. Phew.

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