Magnetic pole reversal

[Aught3]

I just heard a new one about the cause of global warming, that magnetic pole reversals coincide and somehow cause cycles of warming and cooling. A quick google search netted me almost nothing. Has anyone heard of this? Or do you know of a site where this is explained/debunked?

 

[Squawk]

I just heard a new one about the cause of global warming, that magnetic pole reversals coincide and somehow cause cycles of warming and cooling. A quick google search netted me almost nothing. Has anyone heard of this? Or do you know of a site where this is explained/debunked?

First I've heard of it, having done a reasonable bit of research on both at various times (global warming for debating global warming, magnetic reversal for paleomagnetism).

Having said that, I just had a thunk. The magnetic field protects the earth from solar radiation, clearly a changing magnetic field will influence the suns impact on the atmosphere in some way. Definitely something to look into, but not something I am remotely qualified to address properly. I might go and read up though, that could get interesting.

 

[Aught3]

Wait, you've heard about pole reversal contributing to global warming or just heard of both topics separately? I was more interested in the possible connection and finding some info on it.

 

[Squawk]

I only have access to the abstracts.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4MM8BMG-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1127923315&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ddb2c39c739b123408b8748f4136194e

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4GHRC6N-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1127928154&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ec06cbe51b11af1ddeb22c252d69dd5a

Some interesting reading, the answer seems to be that it's yet another factor, but the degree to which it has an effect is as yet unknown.

 

[kf00kaha]

I've got access to the full-texts and now have them on my computer . If you PM your e-mail I can send pdfs.

Conclusions from the first article (Earth and Planetary Science Letters 253(2007)328):

In conclusion, correlations between magnetic variations
and climate may be more significant than
previously realized. We see that no forcing factor, be it
changes in CO2 concentration in the atmosphere or
changes in cosmic ray flux modulated by solar activity
and geomagnetism, or possibly other factors, can at
present be neglected or shown to be the overwhelming
single driver of climate change in the past century. Most
of the time, the prime, joint forcing factor is in solar
variations (at the decadal time scale) or orbital forcing
(at the Milankovic scale). The Sun is clearly a significant
driver of changes not only in climate but in the
overall behavior of the ionosphere and magnetosphere,
and external geomagnetic field; this modulates incoming
fluxes of cosmic rays which are increasingly recognized
as potential drivers of changes in cloud cover
and albedo. The work of Le Mouà«l et al. [29], based on
very sensitive yet robust magnetic indices, shows that
this situation may have prevailed until the mid-1980s.
At longer time scales, we have seen that changes in the
internal geomagnetic field itself might somewhat
unexpectedly trigger significant climate change: archeomagnetic
jerks may be the only evidence that changes
in the internal magnetic field itself can at times have a
significant influence on climate, possibly through the
cosmic-ray/low-cloud connection at times of extremal
tilt of the dipole. Although still in need of confirmation,
their detection is therefore particularly exciting: Gallet
et al. [64] have recently underlined a potential connection
between these geomagnetic events and some
major societal changes in the Middle East through
climatically driven environmental fluctuations (Fig. 5).
A correlation at the longer time scales of Milankovic
cycles remains very speculative at this time.

There was no separate conclusions in the second one, unfortunately. However, there was 135 other articles on ScienceDirect corresponding to the search "dipolar magnetic field global warming ", so there's quite a lot of material. Most of them are not into this specific subject though, just mentioning magnetic reversal ant global warming in the same article.

 

[Squawk]

oooh, fantastic, pm en route

 

[Pulsar]

I'm not a climate scientist, but here's my two cents:

The Earth's magnetic field has been weakening in the past 1500 years, increasing our vulnerability to cosmic rays. Does this have an effect on our climate? Yes, very likely. Does it explain current global warming? Probably not. One reason is similar to an argument used to show that the Sun isn't the culprit: apart from the current low solar activity itself, the temperature increase of our atmosphere is inconsistent with 'extraterrestrial' factors. You would expect a uniform increase in temperature from troposphere to stratosphere and beyond if cosmic rays were to blame. But instead, only the lower troposphere is warming up, not the stratosphere, and that's consistent with heat being trapped by greenhouse gases. See greenman's solar video for more info.

But there are indications that the weakening magnetic field has an impact on tropical rainfall. The idea is that cosmic particle serve as seeds on which water vapour condenses, thus increasing cloud cover and precipitation. Here's an article about it: Link found between tropical rainfall and Earth's magnetic field. Incidently, the Sun's magnetic field also plays a significant role: this article hints at a connection between the Sun's magnetic field and droughts in Australia.

I'll cite the conclusion of the first article:

'Greenhouse gases have a major effect on climate. If our correlation is correct, then we are saying that the Earth's magnetic field may have some effect on rainfall, and the sun's field should have a larger effect on climate'

The magnetic fields are a piece of the puzzle, but they're not the smoking gun.

 

[Squawk]

I'm not a climate scientist, but here's my two cents:

The Earth's magnetic field has been weakening in the past 1500 years, increasing our vulnerability to cosmic rays. Does this have an effect on our climate? Yes, very likely. Does it explain current global warming? Probably not. One reason is similar to an argument used to show that the Sun isn't the culprit: apart from the current low solar activity itself, the temperature increase of our atmosphere is inconsistent with 'extraterrestrial' factors. You would expect a uniform increase in temperature from troposphere to stratosphere and beyond if cosmic rays were to blame. But instead, only the lower troposphere is warming up, not the stratosphere, and that's consistent with heat being trapped by greenhouse gases. See greenman's solar video for more info.

But there are indications that the weakening magnetic field has an impact on tropical rainfall. The idea is that cosmic particle serve as seeds on which water vapour condenses, thus increasing cloud cover and precipitation. Here's an article about it: Link found between tropical rainfall and Earth's magnetic field. Incidently, the Sun's magnetic field also plays a significant role: this article hints at a connection between the Sun's magnetic field and droughts in Australia.

I'll cite the conclusion of the first article:

'Greenhouse gases have a major effect on climate. If our correlation is correct, then we are saying that the Earth's magnetic field may have some effect on rainfall, and the sun's field should have a larger effect on climate'

The magnetic fields are a piece of the puzzle, but they're not the smoking gun.

Pulsar, your post seems to be somewhat self refutting.
The first part of your post details why a decrease in the magnetic field and subsequent increase in cosmic radiation should provide a warming in the upper atmosphere rather than the lower atmosphere. The second part of your post details precisely why this might not be the case. In a word, cloud seeding (ok two words). Increased clouds have an effect on radiation both entering and leaving the earth. If a decreasing magnetic field results in increased cosmic radiation reaching the atmosphere the resulting increased cloud formation could promote warming at ground level, a direct result of the decreased magnetic field.

To say that the earths magnetic field has been decreasing since 1500 is also over simplistic, but unfortunately I don't have enough of a grounding to be authoritative on the subject so I must leave it to someone else. I'm not sure what you mean about a smoking gun, this is just another factor that has an influence on climate, one that needs to be researched to understand its full impact.

 

[Aught3]

If a decreasing magnetic field results in increased cosmic radiation reaching the atmosphere the resulting increased cloud formation could promote warming at ground level, a direct result of the decreased magnetic field.

It depends what types of clouds start forming, thick low clouds that bring lots of rain block more solar radiation than they trap. Too many of them and this would actually lead to global cooling.

 

[Squawk]

If a decreasing magnetic field results in increased cosmic radiation reaching the atmosphere the resulting increased cloud formation could promote warming at ground level, a direct result of the decreased magnetic field.

It depends what types of clouds start forming, thick low clouds that bring lots of rain block more solar radiation than they trap. Too many of them and this would actually lead to global cooling.

I agree, its another area that needs more study. The best evidence I've seen to date was in the aftermath of the world trade center attacks when flights over the US ceased. The upshot was no contrails over the US mainland, and unfortunately I have completely forgotten what the result was, but I know temperatures were affected, I read something on it. Bah, yet more digging I'll have to do.

 

[Aught3]

I agree, its another area that needs more study. The best evidence I've seen to date was in the aftermath of the world trade center attacks when flights over the US ceased. The upshot was no contrails over the US mainland, and unfortunately I have completely forgotten what the result was, but I know temperatures were affected, I read something on it. Bah, yet more digging I'll have to do.

The temperature increased.

 

[Giliell]

I agree, its another area that needs more study. The best evidence I've seen to date was in the aftermath of the world trade center attacks when flights over the US ceased. The upshot was no contrails over the US mainland, and unfortunately I have completely forgotten what the result was, but I know temperatures were affected, I read something on it. Bah, yet more digging I'll have to do.

The temperature increased.

Didn't it sink as well?
As far as I remember (i think it's in one of Potholer's videos) it went up during the day but cooled down during the night because the contrails also keep the heat in

 

[Squawk]

I agree, its another area that needs more study. The best evidence I've seen to date was in the aftermath of the world trade center attacks when flights over the US ceased. The upshot was no contrails over the US mainland, and unfortunately I have completely forgotten what the result was, but I know temperatures were affected, I read something on it. Bah, yet more digging I'll have to do.

The temperature increased.[/quote]
Didn't it sink as well?
As far as I remember (i think it's in one of Potholer's videos) it went up during the day but cooled down during the night because the contrails also keep the heat in[/quote]


That tallys with what i remember, but I don't have the figures or the papers in question, and clealry I am inept at searching google scholar.

 

[xman]

I don't know where I heard it, but I don't think the poles are set to switch for several centuries at least, more likely a few millennia.

 

[Nogre]

Didn't it sink as well?
As far as I remember (i think it's in one of Potholer's videos) it went up during the day but cooled down during the night because the contrails also keep the heat in

Yes, those are the results according to Potholer's videos.

 

[Deleted member 499]

It's a fairly complicated thing to unravel. Assuming a weakening in the magnetic field would cause warming is (as people have already mentioned) based on cosmic particles cloud seeding and trapping more radiation. However, in the discussion paper for the earth and planetary science letters paper quoted earlier in the thread it talks about an increase in magnetic field strength causing warming as well. Essentially using the same mechanism it can be argued that a stronger field means less particles, less clouds and so more radiation reaching the planet. It seems to me that if the mechanism can work both ways then logically it shouldn't have much impact on climate changes, plus I would imagine that the decrease in field strength prior to a reversal would occur too slowly to account for the recent warming trends. I'm not a climatologist though.

The conclusions of the discussion paper are as follows.

With their paper, notably its conclusion, Courtillot et al. (2007) express their doubts about commonly accepted facts concerning the climatic evolution over the last century. This leads them to invoke geomagnetism, through its effect on cloud cover, as an additional climate driver. The compilation of instrumental data shows that the lower atmosphere warmed by about 0.8 ,°C during the 20th century (Jones et al., 1999; Brohan et al., 2006). This period corresponds in time to the rise of greenhouse gases linked to human activities. However, the CO2, CH4 and N2O curves (Solomon et al., 2007) have exponential shapes suggesting that they are not the main cause of the rapid warming from 1920 to 1940 and of the temperature dip and plateau observed between 1940 and 1970 (Fig. 1). Natural causes such as solar or volcanic forcings, as well as anthropogenic aerosols, could have contributed to this initial phase of global warming as well as the transient pause, as modelled for example by Stott et al. (2000) and Meehl et al. (2004). These modelling studies also suggest that the observed acceleration of the temperature rise since ∼30 yrs. probably exceeds the natural variability. This recent warming phase cannot be explained by natural changes in the Sun's output, which are well constrained over the last three decades. As illustrated on our Fig. 3, precise observations of solar irradiance from satelliteborne radiometers, as well as results from neutron monitors recording the influence of cosmic rays on Earth, indicate that external forcings cannot explain the 0.6 ,°C rise in global temperature observed over the past 30 yrs. (Brohan et al., 2006). This conclusion agrees with numerical modelling studies indicating that the rise in the content of atmospheric greenhouse gases is very probably the main cause of the significant warming observed during the last three decades (Stott et al., 2000; Meehl et al., 2004). In summary, as specifically discussed in an abundant literature (Stott et al. (2000;Meehl et al. (2004) to list just two), the climate evolution over the last century can readily be explained by a combination of natural (Sun and volcanoes) and anthropogenic forcings that became significant during the second half of the century. Courtillot et al. (2007) invoked an additional forcing due to a hypothetical link between geomagnetism, cosmic rays and cloud cover. As discussed above, we find no convincing support for such a link in the data and analysis presented by
the authors. Indeed, instrumental data on cosmic rays and heliomagnetic modulation do not show a long term trend that could contribute to the global warming observed over the last half-century (Fig. 3). Thus, there is still no reason to invoke this speculative forcing.

Bard & Delaygue (2007) Earth & planetary science letters, 265, p302-307

However just to make things more interesting, there is a very recent paper (roughly last month) which shows apparent correlation between a period of catastrophic warming during the Palaeocene-Eocene and a major magnetic field fluctuation. So there may be something to it after all, although this paper talks more about transfer of angular momentum between different parts of the earth rather than cloud cover.

Abstract below:

We report high-precision records of a magnetic reversal event at the Paleocene-Eocene thermal maximum (PETM), a cataclysmic global warming event initiated at 55.0 Ma. This event is confirmed by both an antipodal shift in direction and a reduction in magnetic intensity during the lower and upper transitions, and it is seen at additional sites, indicating that the characteristic remanent magnetization (ChRM) was primarily acquired by Earth's magnetic fi eld during sedimentation. This major fl uctuation of Earth's magnetic fi eld intensity is interpreted to have been linked to the PETM and to have eventually facilitated the reversal. This Paleocene-Eocene magnetic reversal (PEMR) lasted for ~53 ka, from 54.964 to 54.911 Ma, but fi nally recovered to an original polarity. This suggests a possible coupling between Earth's core magnetofluid dynamo sphere and the atmosphere-hydrosphere during an abrupt catastrophic climate event.

Lee & Kodama (2009), Geology, 37, p1047-1050

I have both of the papers downloaded if anyone wants them. Also I have access to a fair few journal sites through my university so if anyone wants specific papers (title or ref) I can try and find them for you.

 

[xman]

http://en.wikipedia.org/wiki/Magnetic_pole_reversal

 

[MRaverz]

The magnetic field is weakening??

Shouldn't we be doing something to prevent this? D;

 

[obsidianavenger]

The magnetic field is weakening??

Shouldn't we be doing something to prevent this? D;

lmao!

attach rockets along the equator at intervals of 100 miles or so, point them in the direction of earths rotation and FIRE simultaniously... if we increase the rate of rotation we should be able to create a stronger magnetic field >.>

 

[MRaverz]

The magnetic field is weakening??

Shouldn't we be doing something to prevent this? D;

lmao!

attach rockets along the equator at intervals of 100 miles or so, point them in the direction of earths rotation and FIRE simultaniously... if we increase the rate of rotation we should be able to create a stronger magnetic field >.>

So we're stuffed? D;