[JP (OP)]

JimBob brought up an interesting point in another thread recently: that the earth's magnetic field shields us from a lot of solar particles.  I don't know if these particles carry enough energy to effect the earth's climate, but if they did, you would probably expect to see climate shifts in the historical record corresponding with periods when the earth's magnetic field shifted polarity (http://en.wikipedia.org/wiki/Pole_reversal). 

So my question is: is there any evidence for climate change correlating to magnetic pole reversal?

A secondary question might be: is there any evidence that a weaker magnetic field on a short-term time scale (not long enough to strip the atmosphere) would lead to major climate change, or do the particles it protects us from not have a strong influence on climate?

[yor_on]

It's a hard question to answer, isn't it?

I mean, you could assume that if the magnetic field stopped protecting us there would be all kinds of effects, hard radiation, bird migrations going havoc etc. But then again, that's when that magnetic field isn't there at all. If we assume a gradual weakening instead, before a change (tipping), what would the consequences be for the climate? Could the radiation do something to the cloud formation for example?

Maybe, another one that I don't know So do we have evidence for any increased radiation over the closest decades?

[CliffordK]

I made this chart a while ago.
Ice Core temperatures (bottom) compared to inverted or negative magnetic field strength (top) (from Wikipedia).

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Keep in mind that the field strength of the earth varies significantly.  It has weakened many times in the last 3/4 million years without a reversal. 

It seemed to me that there was an inverse relationship between earth's temperature and the magnetic field strength.

The weaker the magnetic field, the warmer the earth.

Of course, I also noticed that it was all to easy to match up two sets of squiggly lines that may or may not be related.

Anyway, my interpretation was that the sun may be driving the Magnetic field strength on Earth.  For the past 300 years, the sun's magnetic poles have been reversing ever decade or so.  We have always assumed this was the normal state of the sun, although it is known that 350 years ago during the Maunder Minimum, the sun's activity was much different. 

Solar activity may also have been different during previous ice ages with fewer pole reversals, although I don't have a lot of data for that at the moment.

My belief is that the rapid solar pole reversals may be affecting Earth's magnetic field.  Thus, a weak magnetic field may not be causing the earth to warm, but may be a symptom of outside causes of the earth warming.

I'll try to review some articles that I had found related to this and post links later.

[yor_on]

There is one thing that seems to be rather important with us having a magnetic field. It keeps the water, without a magnetic field hydrogen ions will no longer be held in by Earths magnetic field. ('Ions are atoms or molecules that have lost or gained electrons. If atoms lose one or more electrons they become positively charged ions (cations). If they gain one or more electrons, they become negatively charged ions (anions)')

THE IONIC PRODUCT FOR WATER.

[frethack]

I made this chart a while ago.
Ice Core temperatures (bottom) compared to inverted or negative magnetic field strength (top) (from Wikipedia).

This is a really interesting relationship.  The geomagnetic field has been in an overall decline for about the past 200 years, which is coincidentally about the same time that the solar dynamo has been intensifying.  Im not stating this because I believe that solar variability is responsible for glacials, but there is a hypothesis that the geomagnetic field may be at least partially induced by the solar dynamo.  Recently there has been observational evidence of direct interaction through magnetic conduits between the two. 

If I remember correctly, the magnitude of the solar dynamo has an inverse cubed relationship with distance from the sun.  As a first order hypothesis, it is possible that as milankovich cycles increase/decrease the earths average distance from the sun, the geomagnetic field strengthens/weakens.  It could also be entirely coincidental.  It would be good to know a little more about the data sets used to create these plots...resolution, dating methods, error, etc.  Longer records would be great as well, but unfortunately, this is about as far back as decently resolved paleoclimate records can conceivably go.

[yor_on]

Frethack, can you give us a link with some facts too?
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By the way, when I asked about the radiation I really was thinking of the closest 250 years to us, as that is where we see a statistical anomaly appear, and accelerate, not seen before in Earths history. That is the timeslot I'm interested in, not the millions of years Earth have existed. If you want to bind a magnetic field to the warming, then that's where you have to look.  And if it is so, then there need to be a geomagnetic anomaly that is accelerating too, in one direction time wise.

Global warming today is a anomaly, not a phase we have found anywhere else in Earths history. That as I assume that this was what the thread was about? Treated otherwise it's not connected to the warming, instead becoming a question of geomagnetism. When it comes to the suns importance I would be surprised if it didn't play a role. But if you read Changing Sun, Changing Climate? you can see why it's only a very few scientists expecting it to be the sole culprit.

[frethack]

Frethack, can you give us a link with some facts too?

It will take me a day to post a few papers, but I will be happy to do so. (working on final papers for classes currently)

By the way, when I asked about the radiation I really was thinking of the closest 250 years to us, as that is where we see a statistical anomaly appear, and accelerate, not seen before in Earths history.

There would be very little way to demonstrate whether the current magnetic field degeneration is an anomaly or not without looking much deeper than 250 years.  The earth operates on time scales much larger than this.

Global warming today is a anomaly, not a phase we have found anywhere else in Earths history. That as I assume that this was what the thread was about? Treated otherwise it's not connected to the warming, instead becoming a question of geomagnetism. When it comes to the suns importance I would be surprised if it didn't play a role. But if you read Changing Sun, Changing Climate? you can see why it's only a very few scientists expecting it to be the sole culprit.

Our current warming is not anomalous...there are many instances when the earth has warmed/cooled at this rate (and even faster).  No need to read the book...solar-terrestrial climate coupling is my area of research (along with drought occurrence and severity).  I dont know of a climate scientist that believes that the sun is solely responsible for the current warming, but the magnitude of the sun's influence is not insignificant.  Ill post recent research on this as well if you like.  Give me a day or so.

[yor_on]

Yes, the Earth does, but we should be able to spot a correlation in those 250 years. It's no little degree of warming we've had. And I still say it's an anomaly, not seen happening at such a fast pace before. That doesn't state that if all the worlds volcanoes would start to spew simultaneously and continuously we couldn't have a similar effect, although ? I think we would need some more than those we have for now for that.

(Hmm, that one was not that good a analogue I'm afraid, although volcanoes do emit a lot of CO2 they also emit, a lot, of particles shielding the Earth from the suns rays. That's also what many expect to have caused the 'Little Ice Age'. If there is little sun to 'warm' the CO2 molecules being released, little heat will be kept by them. The records suggest the temperature cooling around 1250, getting warmer momentarily in the 1500, begetting the coldest climate around 16-1800 coinciding with the Maunder Minimum (sunspots disappearing), not turning to a warmer climate until around 1850. The average global temperatures were then down to a 1 to 1.5 degree Celsius colder than today, and many living in Europe seemed to have thought it Gods judgment on them, wondering what they had done to displease him.)


=Quote

Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.

All three major global surface temperature reconstructions show that Earth has warmed since 1880. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. Even though the 2000s witnessed a solar output decline resulting in an unusually deep solar minimum in 2007-2009, surface temperatures continue to increase.

The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969

The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.

Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa.

The carbon dioxide content of the Earth’s oceans has been increasing since 1750, and is currently increasing about 2 billion tons per year. This has increased ocean acidity by about 30 percent.

From NASA.

And we know that the atmospheric content has changed.

"These unique satellite spectrometer data collected 27 years apart show for the first time that real spectral differences have been observed, and that they can be attributed to changes in greenhouse gases over a long time period," says John Harries, a professor at Imperial College in London and lead author of the study published today in Nature. As the sun's radiation hits the earth's surface, it is reemitted as infrared radiation. This radiation is then partly trapped by the so-called greenhouse gases: carbon dioxide (CO2), methane (CH4) and chlorofluorocarbons (CFCs) as well as water vapor. Satellites can measure changes in the infrared radiation spectrum, allowing scientists to detect changes in the earth's natural greenhouse effect and to deduce which greenhouse gas concentrations have changed.

The researchers looked at the infrared spectrum of long-wave radiation from a region over the Pacific Ocean, as well as from the entire globe. The data came from two different spacecraft the NASA's Nimbus 4 spacecraft, which surveyed the planet with an Infrared Interferometric Spectrometer (IRIS) between April 1970 and January 1971, and the Japanese ADEO satellite, which utilized the Interferometric Monitor of Greenhouse Gases (IMG) instrument, starting in 1996. To ensure that the data were reliable and comparable, the team looked only at readings from the same three-month period of the year (April to June) and adjusted them to eliminate the effects of cloud cover. The findings indicated long-term changes in atmospheric CH4, CO2, ozone (O3) and CFC 11 and 12 concentrations and, consequently, a significant increase in the earth's greenhouse effect. "

So it's a accelerating effect starting from about 250 y ago as I think of it, up to now, fitting perfectly with our industrial revolution. For it to be the magnetic field I would expect some sort of correlation to be observable over that period.

[yor_on]

There are interrelated subjects here it seems. We have the Earths own magnetic field, we also have the impact of the suns activity on it. As I said, I'm agreeing on that the sun must have a influence, but I don't expect it to drive the warming we see now. If we look at this image from NASA.

We can see that the Suns activity had a downward trend since 2002, staring to climb again around 2010, but very slowly, until 2011 where it 'kicks off' real good. So yes we're going into a solar maximum some time 2013, according to NASA. If the sun would drive the Earths magnetic field and in that way, assuming that we could blame the magnetic field for our warming, be responsible. Why does the temperature curves just keep climbing?

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In spite of a La Nina and sunspots too? Take a look at NASA's Temperature Record. But yes, the geomagnetic field definitely seems to weaken. But there are some things we can add to that effect. "According to Earth's geologic record, our planet's magnetic field flips, on average, about once every 200,000 years. The time between reversals varies widely, however. The last time Earth's magnetic field flipped was about 780,000 years ago. "We hear the magnetic field today looks like it is decreasing and might reverse. What we don't hear is it is on a time scale of thousands of years," Glatzmaier said. "It's nothing we'll experience in our lifetime." From National Geographic. Earth's Magnetic Field Is Fading.

And "Reversals take a few thousand years to complete, and during that time--contrary to popular belief--the magnetic field does not vanish. "It just gets more complicated," says Glatzmaier. Magnetic lines of force near Earth's surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird. But it's still a planetary magnetic field, and it still protects us from space radiation and solar storms. " From Earth's Inconstant Magnetic Field.

And finally a temperature scale over the last thousand years.

From  Past Climate Change; US environmental Climate Change.

As compared to this;

From NASA 2008. "Hathaway has studied international sunspot counts stretching all the way back to 1749 and he offers these statistics: "The average period of a solar cycle is 131 months with a standard deviation of 14 months. Decaying solar cycle 23 (the one we are experiencing now) has so far lasted 142 months--well within the first standard deviation and thus not at all abnormal. The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values." In summary, "the current minimum is not abnormally low or long." The longest minimum on record, the Maunder Minimum of 1645-1715, lasted an incredible 70 years. Sunspots were rarely observed and the solar cycle seemed to have broken down completely. The period of quiet coincided with the Little Ice Age, a series of extraordinarily bitter winters in Earth's northern hemisphere. Many researchers are convinced that low solar activity, acting in concert with increased volcanism and possible changes in ocean current patterns, played a role in that 17th century cooling."

[frethack]

Why does the temperature curves just keep climbing?

You are assuming in this line of thought that the sun is the ONLY factor on climate, disregarding "ocean memory", greenhouse gasses, climate oscillations, etc.  This is a fallacious argument.  As this post is about the geomagnetic field and climate, Ill start a new thread on solar influences on climate instead of hijacking this one for yet another futile debate. 

As the on topic part of this post, and to show direct interaction between the geomagnetic field and the solar magnetic field:

http://science.nasa.gov/science-news/science-at-nasa/2008/30oct_ftes/

Look these papers up with google scholar:

Evidence for a flux transfer event generated by multiple X-line reconnection at the magnetopause
Concerning the occurrence pattern of flux transfer events on the dayside magnetopause
Cluster observations of "crater" flux transfer events at the dayside high-latitude magnetopause

As for the decline in geomagnetic intensity and the overall increase in solar activity, there is surprisingly little in the peer reviewed literature.  As stated before:

...geomagnetic field strengthens/weakens.  It could also be entirely coincidental.  It would be good to know a little more about the data sets used to create these plots...resolution, dating methods, error, etc.  Longer records would be great as well, but unfortunately, this is about as far back as decently resolved paleoclimate records can conceivably go.

There is a lot to discover...more than we can conceive.

[yor_on]

I'm not disputing that Frethack. I have the same feeling, that there are a lot of connections still to be found. As for the other interactions you mention I did not disregard them. There are all sorts of feedbacks involved, and they make earth a dynamic non-linear system. I just stated that I could see no direct forcing or correlation between the sun and the temperature. But we know that the sun is what warms this Earth, without it Earth would, very fast, become to cold to live on.

It's a complex system.

[frethack]

I just stated that I could see no direct forcing or correlation between the sun and the temperature.

See the next topic