Earth's weakening magnetic field/solar storms

[Phobos]

Hope I'm not bombarding you with questions, Lisa! Apparently, Earth's magnetic field is weakening quite rapidly. So does that mean that minor solar storms can impact the grid, and be capable of causing more outages?

[lisa]

Hi Phobos,

Not at all!!!

Apparently, Earth's magnetic field is weakening quite rapidly. So does that mean that minor solar storms can impact the grid, and be capable of causing more outages?

So, let's start at taking a look at what this actually looks like. Here's a plot showing the evolution of the Axial Dipole Moment for the Earth's magnetic field:



In this case, time is going from right to left, because it is showing age - so the most recent time is on the far left. As you can see, we've been at a bit of a maximum as far as the Earth's polar field goes, so it makes sense that once the decline starts it would probably be quite rapid. That being said, take a look at the units of the plot. They are 'ka', i.e., thousands of years. So when we say rapid, we're talking on geological time scales! This means, even if we are headed for a reversal, it is not going to happen anytime soon.

In terms of what a reversal means for life on Earth - it will go on. There is evidence that the weakening of the Earth's field has historically been linked to some excess radiation, which can cause mutations and thus spur an enhanced period of evolution. But, there is no indication that it has ever cause any extinction events. In terms of what it might mean to technology, that is anyone's guess - I mean who knows what technology would even look like when it does finally occur!! However, here's a couple interesting articles that discuss what it might look like if it *were* to happen any time soon:

https://www.scientificamerican.com/arti ... -expected/
https://www.quora.com/What-will-happen- ... -our-hands

I hope this helps!

Cheers!
-Lisa

[Phobos]

This is really interesting, thanks!

[Phobos]

I have another question which is most probably totally off the wall, and please feel free to ignore it. But is there any possibility that solar activity could cause Earth's mag field to reverse, and are reversals or magnetic excursions on Earth more likely to happen when solar activity is low?

[lisa]

Hi Phobos,

The Earth's magnetic field is generated by the liquid Iron in Earth's core. As the magma that makes up the fluid iron core moves, it generates a moving electric current, which in turn generates Earths magnetic field. (This is know as a dynamo and is also occurring in the Sun). So, the reversals are caused by changes in these motions. Here is a link to a page that describes and illustrates the geodynamo https://websites.pmc.ucsc.edu/~glatz/geodynamo.html. While solar activity can impact the Earth's outer magnetic field, it doesn't really impact the motions of liquid iron in the core, and so the Earth's magnetic reversal are independent of the Solar activity.

Cheers!
-Lisa

[Phobos]

Thanks Lisa!

[misu]

What happens during a solar maximum? What does a solar storm do to the earth?

[lisa]

Dear Misu,

Thank you for your question!

What happens during a solar maximum?

During solar minimum, the Sun experiences and increase in all types of activity, such as sunspots flares, and coronal mass ejections.

What does a solar storm do to the earth?

Most times the Earth is protected by our magnetic field as illustrated in this cool video: https://www.youtube.com/watch?v=XJ5bcZITOiE. However, sometimes, it can cause magnetic reconnection as shown in this video: https://svs.gsfc.nasa.gov/20057. Usually this just produces the aurora, but If the storm is powerful enough, the storm could impact satellites, interfere with GPS communications, and even disrupt the power grids.

I hope this helps!

Cheers,
-Lisa

[Phobos]

Hi Lisa,

What do you think the chances are of another Carrington Event occurring?

[lisa]

What do you think the chances are of another Carrington Event occurring?

Hi Phobos,

Another great question! I think that there is no doubt that another Carrington Event will occur - the real question is when? Unfortunately, we don't have enough data to really iron out those statistics. However, some people have tried to look at ice core data and there are some that estimate that a Carrington-class event will impact the Earth on average ever 150 years or so. Since the Carrington event occurred in 1859, they argue that we are about due for another one. However, we may never see one in our lifetimes.

In the last few decades, we've been able to view a few major geomagnetic storms. In 1989 there was a severe storm that knocked out the power for most of Quebec. https://en.wikipedia.org/wiki/March_198 ... etic_storm. Just a few years ago, on July 23rd of 2012, there was a Carrington-class storm that just missed the Earth. https://en.wikipedia.org/wiki/Solar_storm_of_2012. Studies have estimated that if it had actually impacted the Earth, it would have cost trillions of dollars and recovery effort would have take 4-10 years!


Cheers,
-Lisa