Thread: Earth's magnetic reversal. What dangers are present?

Hi, I'm new here, and you all seem very knowledgeable. I wanted to drop a question that's been bugging me for a time. Of all the climate change topics and various other things that seem to be affecting the Earth, I wanted to gather your take on what the potential dangers are or what danger swill there be when the Earth once again reverses it's magnetic poles.

I may be completely off-base here, and please correct me if I am, but it appears that the greatest threat (at least to humanity) when the changing of poles occurs is when they're in temporary equilibrium (there's neither a strong north or south pole for a time)... in which case there'll temporarily be no "magnetic shield" to fend off the majority of solar wind that comes our way. I distinctly remember a History channel show showing the essential effects of this if we were to receive a strong enough solar wind burst to "break" our magnetic shield. The described effects of this were essentially a quick and cancerous death by radiation. I understand that it being the History channel, it's probably sensationalized for ratings...but it intrigued me enough to bring it up here.

Anyway, felt like this would be a good shake-up topic from the majority of topics I've looked at here, hopefully I get some more qualified replies and answers than my own uneducated ideas : )

Technically it does shield the Earth from ionizing radiation... but that's just a first defence. Our atmosphere also offers good protection when given the chance.

I'll add that reversals proceed at glacial speeds (at least thousands of years), in case History Channel suggested sudden catastrophe.

Originally Posted by Pong

Technically it does shield the Earth from ionizing radiation... but that's just a first defence. Our atmosphere also offers good protection when given the chance.

I'll add that reversals proceed at glacial speeds (at least thousands of years), in case History Channel suggested sudden catastrophe.

Good to hear our shield only does some of the work (though I think it's still an important part)

Nah, the History Channel really only showed a cataclysmic event that probably won't happen (something along the lines of a gigantic solar flare shooting directly at Earth, effectively overloading the magnetosphere with too much radiation)

I'm more interested in the fact that the reversal of poles DOES take several thousands of years, as I think this would leave at least window of several years in which the Earth would not really have a strong magnetic field present

Maybe it's just kind of what you implied, and the majority of problems associated with that are taken care of by our atmosphere during that time...I hope that's the case

It's also been hypothesized that the magnetosphere isn't totally gone during a reversal, though it might be significantly reduced. Thus it'll still provide sufficient protection against cosmic rays.

At either rate, there are many, many reversals noted in the last few million years and there is no pattern of mass extinction present in the fossil records of any of them. Therefore, one can conclude that there is little affect on the biosphere. We may have some problems with compasses during that time, but it shouldn't overly affect us.

Ask yourself why polar bears still exist.

Originally Posted by Ophiolite

Ask yourself why polar bears still exist.

[off topic]Maybe the cockroaches will have some company when the nuclear holocaust comes. [/off topic]

Originally Posted by GaussWaffle

Hi, I'm new here, and you all seem very knowledgeable. I wanted to drop a question that's been bugging me for a time. Of all the climate change topics and various other things that seem to be affecting the Earth, I wanted to gather your take on what the potential dangers are or what danger swill there be when the Earth once again reverses it's magnetic poles...

whether reversals take decades or millennia to complete,
the most significant dangers are likely to be -

your magnetic compass is stuffed,
and wholly unreliable without an up-to-date degree adjustment report
(probably added in to the daily weather report ...
"today magnetic north was 35, 87, 101, and 153 degrees from true -
tomorrow will be unpredictable" ...)

you might have to put up with occasional late night auroral sky shows in warmer latitudes
for a while ...

thanks for the input, it waylays my worries much more to know we're not all DOOOOOOOOMED...which makes total sense considering how well life has survived previous magnetic reversals

Assuming humans still exist when our next pole reversal is complete...that means the water will start flushing clockwise for use Northerners, right?

thanks for the answers

Originally Posted by GaussWaffle

Assuming humans still exist when our next pole reversal is complete...that means the water will start flushing clockwise for use Northerners, right?

LOL. I would have to refer you to Mythbusters and Snopes.com for that one. This myth is based on the Coriolis effect and, thus, the spin of the Earth rather than the Earth's magnetism or magnetic field. The reduction or even loss of Earth's magnetic field wouldn't diminish the Coriolis effect. And this effect is only noticeable on a global scale rather than one of a few inches (i.e. the toilet).

Originally Posted by Ophiolite

Ask yourself why polar bears still exist.

To reduce the number of radioactive seals.

I've never looked into it, but If what I hear is correct, we have had a measurable reduction in the magnetic field strength over the years. How this affects the climate? Who knows. I would say it's possible for some of the changes we see, but only to a very minor degree. Probably not measurable. I keep an open mind to the possibility as one reason for Global Warming, but that's about it. Not something I will attempt to argue as a cause.

I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

did anyone actually mention the magnetic field or lack thereof affecting the global climate - presumably that's not impossible, but i thought the danger was supposed to come from cosmic radiation no longer being deflected by the magnetic field (or at least not to the same extent) ?

Originally Posted by Wild Cobra

...
I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

No please, do tell:
what is this "proxy" data?
and what else could leave the "proxy" data that we assume as pole reversal?

Jeeze Cran, he's just tossing up an idea. A little unpunished brainstorming won't kill us.

Originally Posted by Pong

Jeeze Cran, he's just tossing up an idea. A little unpunished brainstorming won't kill us.

hence the encouragement and questions, Pong -

it's hard to brainstorm a dead-end ...

Originally Posted by Cran

Originally Posted by Wild Cobra

...
I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

No please, do tell:
what is this "proxy" data?
and what else could leave the "proxy" data that we assume as pole reversal?

I said "what if" and I don't know what it would be. I simply keep an open mind, and would hope other scientits do too.

Originally Posted by Wild Cobra

... and would hope other scientits do too.

freudian slip ?

Originally Posted by marnixR

Originally Posted by Wild Cobra

... and would hope other scientits do too.

freudian slip ?

Simple typo.

Originally Posted by Wild Cobra

Originally Posted by Cran

Originally Posted by Wild Cobra

...
I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

No please, do tell:
what is this "proxy" data?
and what else could leave the "proxy" data that we assume as pole reversal?

I said "what if" and I don't know what it would be. I simply keep an open mind, and would hope other scientits do too.

but what is this "proxy" data you refer to, or is that a "what if" thing as well?

Originally Posted by Cran

but what is this "proxy" data you refer to, or is that a "what if" thing as well?

Why are some of you expecting more than I have said?

Fact is, we have no way of knowing what really happened so long ago. Our best theories suggest certain things that could be true.

True science requires the ability not to stop short of one, or a few possibilities.

We continually add to our understanding of science. It is possible that in the future, we find things to dispel notions we have today on this topic. I can make guesses, but I prefer not to.

Originally Posted by Cran

Originally Posted by Wild Cobra

...
I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

No please, do tell:
what is this "proxy" data?
and what else could leave the "proxy" data that we assume as pole reversal?

The proxy data is mostly by the orientation of magnetic minerals in rocks and sediments as they've been created or layed down and then preserved. There are pretty detailed maps of these changes over time and virtually no doubt that these events actually happened.

Originally Posted by Lynx_Fox

Originally Posted by Cran

Originally Posted by Wild Cobra

...
I agree with others, that it is something that takes a very long process. Also, just because we see indications in the geological records that the poles have reveresed, is it something we can really accept as factual? What if something else left the proxy data that we assume as pole reversal?

Just another thought that may or may not have merit.

No please, do tell:
what is this "proxy" data?
and what else could leave the "proxy" data that we assume as pole reversal?

The proxy data is mostly by the orientation of magnetic minerals in rocks and sediments as they've been created or layed down and then preserved. There are pretty detailed maps of these changes over time and virtually no doubt that these events actually happened.

Just to clarify; magnetic striping is seen in the volcanic rocks found at mid-ocean ridges/spreading centres - not in the sediments laid down upon them. As volcanic material is erupted onto the sea-floor, the magnetite (and other magnetic minerals) within the rock will align themselves to the current day magnetic field and be preserved as the rock crystallises fully.

Originally Posted by Lynx_Fox

The proxy data is mostly by the orientation of magnetic minerals in rocks and sediments as they've been created or layed down and then preserved. There are pretty detailed maps of these changes over time and virtually no doubt that these events actually happened.

no, not in sediments; in marine and terrestrial volcanic deposits -
and the data is not "proxy"; it's direct mapping of the magnetic alignment at the time of crystallisation ...

proxy data is eg - measuring variations in oxygen isotopes to estimate sea temperatures; measuring pressure to estimate height or depth; measuring depth and gradient from MOR to sea floor to estimate age or spreading rate ...

measuring magnetic alignment to determine the magnetic alignment is about as direct as you can get ...

Originally Posted by markhaldane

Just to clarify; magnetic striping is seen in the volcanic rocks found at mid-ocean ridges/spreading centres - not in the sediments laid down upon them. As volcanic material is erupted onto the sea-floor, the magnetite (and other magnetic minerals) within the rock will align themselves to the current day magnetic field and be preserved as the rock crystallises fully.

This is an area I'm unfirmiliar with, but do geologists assume they align with the core magnet, or as a compass does?

maybe we interpret the results wrong?

Series and parallel will be opposite one another.

I never meant to side-track this discussion with the possibility were were wrong about pole swapping.

The only thing I think would occur with a reduction to reversal of the magnetic pole is what happens to the hole in the ozone layer. It currently varies in size at the south pole. I believe the ozone layer would diminish as the magnetic field weakens, then effectively reestablish a layer at the south pole, and move to the north pole. During the time the field weakens, I believe we would be have far more UV than normal making it to the surface.

Am I right? I don't know. Again, this is an area of the geosciences I am real weak on.

Originally Posted by Wild Cobra

This is an area I'm unfirmiliar with, but do geologists assume they align with the core magnet, or as a compass does?

Originally Posted by markhaldane

As volcanic material is erupted onto the sea-floor, the magnetite (and other magnetic minerals) within the rock will align themselves to the current day magnetic field and be preserved as the rock crystallises fully.

so, not with the core magnet, but with the magnetic field generated by the outer core -
something like a snapshot compass, but in 3D;
it not only aligns according to magnetic N-S, but also according to latitudinal arc from the poles -
at 90 deg from pole, it's flat; at 0 deg from pole, it's vertical ...

time resolution is such that we can see the changes in a flood basalt deposit,
or any series of volcanic or magmatic deposits, and distinguish between
plate motion (north-south and rotational), true polar wander (which looks a bit like epicycles or parts thereof),
and polar reversals (which show very little or no transition - hence the geologically "sudden" conclusion) ...

Originally Posted by Wild Cobra

maybe we interpret the results wrong?

well, if we do then we are making consistent wrong interpretations
with modern volcanic examples (Hawaii, Iceland, Ring of Fire, etc plus MORs) ...

which means we are exactly as wrong about where today's magnetic poles
(and field lines and field strengths) are with respect to the sampling sites
as we interpret for older volcanic deposits ...

it's the level of confidence in this one form of data throughout geological time
that leads to all sorts of conclusions about other things -
supercontinents and where they were; dipole/octopole fun and games;
snowball earth scenarios; deep time global climate (hothouse/icehouse eons); etc ...

Originally Posted by Wild Cobra

The only thing I think would occur with a reduction to reversal of the magnetic pole is what happens to the hole in the ozone layer. It currently varies in size at the south pole. I believe the ozone layer would diminish as the magnetic field weakens, then effectively reestablish a layer at the south pole, and move to the north pole. During the time the field weakens, I believe we would be have far more UV than normal making it to the surface.

yes, with weakening (or even temporary loss) of the magnetic field strength, that could well happen ...
as could increased disruptions to surface power grids and atmospheric communications ...

how long the extreme kind of situation* could last is not something geology can answer from the record -
which suggests a human scale time frame ...

*meaning null pole or zero field strength - the actual polar reversal -
field weakening and multipole events are measurable, and show up near reversal boundaries ...
it's from these that time frames of centuries to multi-millennia are estimated ...

Originally Posted by Cran

Originally Posted by Lynx_Fox

The proxy data is mostly by the orientation of magnetic minerals in rocks and sediments as they've been created or layed down and then preserved. There are pretty detailed maps of these changes over time and virtually no doubt that these events actually happened.

no, not in sediments; in marine and terrestrial volcanic deposits -
and the data is not "proxy"; it's direct mapping of the magnetic alignment at the time of crystallisation ...

USGS has dozens of paleomagnetic studies based on sediments. (one posted below) http://pubs.usgs.gov/of/1996/of96-294/of96-294.html

measuring magnetic alignment to determine the magnetic alignment is about as direct as you can get ...

You might be right about proxy according the conventions of geology. From someone outside the field the direct measurements of polarity even at a known depth could seem to be a proxy for location of the geomegnetic poles on the planet. I completely agree as long as the time of the particle was layed down is accurate it would be more direct measurement than say tree-rings to temperature.

Originally Posted by Lynx_Fox

Originally Posted by Cran

Originally Posted by Lynx_Fox

The proxy data is mostly by the orientation of magnetic minerals in rocks and sediments as they've been created or layed down and then preserved. There are pretty detailed maps of these changes over time and virtually no doubt that these events actually happened.

no, not in sediments; in marine and terrestrial volcanic deposits -
and the data is not "proxy"; it's direct mapping of the magnetic alignment at the time of crystallisation ...

USGS has dozens of paleomagnetic studies based on sediments. (one posted below) http://pubs.usgs.gov/of/1996/of96-294/of96-294.html

We were discussion palaeomagnetic striping either side of a MOR though, which is in basalts, not sediments. I can't imagine how any continentally derived magnetic minerals would find themselves in the sediment that far out at sea, though I may be wrong. Perhaps winds blowing out from the Sahara could carry them as far as the mid-atlantic ridge?

Originally Posted by Lynx_Fox

USGS has dozens of paleomagnetic studies based on sediments. (one posted below) http://pubs.usgs.gov/of/1996/of96-294/of96-294.html

sediment palaeomagnetics are limited in scope (hence your finding of dozens), and are not considered reliable sources for alignment mapping ...

the document you've quoted explains what was attempted, and why the location was suitable for the trial ...

... Volcanic activity in the catchment was identified as a factor that influenced the magnetic mineralogy and geochemical properties of the sediment. The magnetic and geochemical results will further be compared to detailed pollen analysis, currently undertaken by Katherine Hakala ( University of Pittsburgh) and Prof. Cathy Whitlock (University of Oregon), to test the possibility that variations in the magnetic mineralogy are related to paleoclimatic change and associated watershed processes. This report also describes the methods used to obtain the magnetic and geochemical results. The site, drilling procedure, and core lithology are described by Adam et al. (1994). ...

...Paleomagnetic Data

... Subjective quality: A subjective grade (a is best, c the worst) given to the orthogonal vector diagrams from which the best fit line was calculated. NR indicates that the sample was not rated.

Comments:

* disturbed: Core was disturbed prior to sampling. The orientation of the sample was uncertain and therefore paleomagnetic directions were not calculated on these samples.
* poor fit: The vector diagram was extremely poor, and thus either paleomagnetic directions were not calculated or best-fit line used 2 points.
* not used: Applies to samples in which sediment was displaced during measurement using a magnetometer. A constant orientation could not be assured, and the sample was not used for paleomagnetic analysis.

for timing, we have to rely on radiometric dating processes, with all of its attendant fun and games - but again, the margins and interpretations are consistent (meaning that if there is a common error, it's across the board) ...

compared with the size of the Earth (and the extent of the geomagnetic field), depth of potential sample is negligible (ie, less than margins of error, and swamped by other factors such as variations to local field intensity) and not really an issue ...

I suppose, by analogy, that using a GPS to determine the latitude and longitude where you are on the Earth might be considered a proxy to figuring out where you stand with respect to the equator and the prime meridian ...