Quote: No, you misunderstand. What contradictory evidence has been presented here? That is my question. You brought it up.
I've been waiting years for him to post something substancial. I think he has a fetish for fuzzy haired bananas and middle aged fembots just because they are the only names he knows.
Speaking of aging Japs with fuzzy hair....
YouTube - 2012 Leaks Found in Earths Magnetic Field
Geological Survey of Canada
Geomagnetism
Long Term Movement of the North Magnetic Pole
Introduction
See also:
In-depth
The accompanying figure shows the path of the North Magnetic Pole since its discovery in 1831 to the last observed position in 2001. During the last century the Pole has moved a remarkable 1100 km. What is more, since about 1970 the NMP has accelerated and is now moving at more than 40 km per year. If the NMP maintains its present speed and direction it will reach Siberia in about 50 years. Such an extrapolation is, however, tenuous. It is quite possible that the Pole will veer from its present course, and it is also possible that the pole will slow down sometime in the next half century.
The strength and direction of the Earth's magnetic field slowly change with time – a phenomenon referred to as secular change or secular variation. The cause of secular variation is related to the process by which the magnetic field is generated. Secular change occurs everywhere on Earth, but the magnitude of the change varies from place to place and also with time.
The magnetic field in the region of North Magnetic Pole experiences secular variation just like the magnetic field at any other location on the Earth's surface. To illustrate how this leads to the movement of the Magnetic Pole, consider Observer A , standing at the North Magnetic Pole on January 1. On that day he observes that the inclination is exactly 90°, as expected. Repeat observations made at exactly the same spot during the year show that the inclination is slowly decreasing. On January 1 of the following year he observes an inclination of 89° 57'. During the same time interval, Observer B, who is standing 40 km northwest of Observer A notices that the inclination has increased to 90°. He is now at the North Magnetic Pole. So the slow motion of the Magnetic Pole across the Arctic is due to the secular variation of the magnetic field, a process that originates in the outer core of the Earth, approximately 3000 km below the surface.
Geomagnetism
Long Term Movement of the North Magnetic Pole
In-depth
See also:
Introduction
The change in velocity of the North Magnetic Pole since the early 1970s has been remarkable – 9 km/yr to 41 km/yr. This is clearly seen in the accompanying plot which shows the average rate of motion between observations as a function of time. The acceleration has also increased from 0.22 km/yr2 to 2.21 km/yr2. A change in the velocity of the North Magnetic Pole must be reflected in a corresponding change in both the inclination and the horizontal component of the magnetic field (H). Data from
Resolute Bay Observatory, the nearest to the North Magnetic Pole, show that the annual change in H has increased from roughly -10 nT/yr to almost 70 nT/yr during the past half century (top panel of diagram). The increase has not been uniform, but as a series of steps that have occurred in approximately 1970, 1979 and 1990.
Changes in the magnetic field characterized by an abrupt change in the secular variation have been named "(geo)magnetic jerks" or "geomagnetic impulses". Six jerks of global extent have occurred during the past century: in 1901, 1913, 1925, 1969, 1978 and 1992. The last three jerks can be seen clearly as abrupt changes in the slope of the annual change in H at Resolute Bay. The 1969 jerk corresponds to the start of the increase in the speed of the NMP and the two subsequent jerks, especially that near 1992, appear to correlate with additional increases in the speed.
In contrast to its present-day acceleration, the Magnetic Pole showed little apparent motion between 1831 and 1904. It seems highly unlikely that the Pole actually remained stationary for 73 years, but there are no direct observations from which we can determine its motion during that time period. However, we can use spherical harmonic models produced for this time period to infer the track of the North Magnetic Pole. The accompanying plot shows North Magnetic Pole positions at 20 year intervals between 1820 and 1920 calculated from the spherical harmonic models produced by Jackson and colleagues. The model positions are slightly displaced to the north-west of the observed positions. If we adjust the track to best match the observed positions we find that the Magnetic Pole reached its southernmost latitude, 68.8°, in 1860. The year is significant since 1860 is the year of a possible magnetic jerk.
Spherical harmonic models can also be used to estimate the position of the North Magnetic Pole back to approximately 1600. Prior to that time there were too few observations from which reliable models can be produced. It appears that the North Magnetic Pole moved southeast a distance of approximately 860 km between 1760 to 1860. Prior to that is was located in a relatively confined area near 75° N, 110° W.
Geological Survey of Canada
Geomagnetism
Magnetic field reversals
The Earth's magnetic field is aligned roughly along the spin axis and has an approximate dipole shape, similar to that of a bar magnet, with north and south magnetic poles. This is the normal state of affairs, but occasionally the magnetic field switches polarity, the north and south magnetic poles reverse, and the field settles down in the opposite state. The process goes by several names – "magnetic field reversal" and "polarity transition" are the most common.
Reversals have been documented as far back as 330 million years. During that time more than 400 reversals have taken place, one roughly every 700,000 years on average. However, the time between reversals is not constant, varying from less than 100,000 years, to tens of millions of years. In recent geological times reversals have been occurring on average once every 200,000 years, but the last reversal occurred 780,000 years ago. At that time the magnetic field underwent a transition from a "reversed" state to its present "normal state".
We get our information about reversals from certain types of rock in which information about the direction of the magnetic field is imprinted. When igneous rocks, which may form inside the Earth or on its surface, cool and solidify they acquire a magnetization parallel to the ambient magnetic field. If the rock cools quickly, as would a lava flow, it acquires an almost instantaneous record of the magnetic field. Slowly cooling rocks, such as those that form inside the Earth, acquire a record of the magnetic field smeared over a much longer period of time. Sedimentary rocks acquire their magnetizations as each individual grain of sediment aligns itself in the direction of the magnetic field as it is deposited.
Occasionally certain rocks can tell us more than just the polarity of the magnetic field at their time of formation. Sometimes, lava flows occur frequently enough, or sediment deposition is fast enough, that we can actually determine the change in direction and field intensity during the reversal itself. These occurrences are relatively rare, and the information sometimes ambiguous, but here is what researchers have learned.
- Although fast by geological standards, reversals are by no means quick on the human time scale. They take roughly 5,000 years, with estimates ranging from 1,000 years and 8,000 years.
- Both the total magnetic field and its dipole component decrease substantially during a reversal to values that range from 10% to 25% of the pre-reversal strength.
- A reversal does not proceed in a uniform fashion. Large and rapid changes in direction and intensity are punctuated by periods of little change. During some transitions the field starts to change but then rebounds to near normal before the reversal finally goes to completion.
- The scarcity and ambiguity of observations have led to two competing theories explaining how the magnetic field pattern changes, and how the magnetic poles behave during a reversal. According to one theory, the magnetic field remains predominantly dipolar during a reversal, and the poles migrate along preferred paths from one hemisphere to the other. According to another theory, the dipole portion of the magnetic field shrinks to zero but then regrows with opposite polarity. During the interval during which there is no dipole, the non-dipole part of the field persists, and the magnetic poles would not migrate in a systematic fashion.
Although other mechanisms – such as meteor impacts – have been postulated, it is generally agreed that reversals occur because of some change in the dynamo process that generates the magnetic field. The simplest explanation is that convection in the outer core ceases, allowing the magnetic field to decay. Eventually, heat build up will start convection going again and a new field will form whose polarity will depend on the polarity of any residual field at the spot where convection restarts. The problem with this theory is that reversals take only 5,000 years, but it takes 15,000 years for the field to decay. Ultimately, the occurrence of reversals must be related to changes in the fluid flow in the outer core. In fact, there is evidence, borne out by computer simulations, that fluid motions try to reverse the field every few thousand years, but that the inner core acts to prevent reversals because the field cannot diffuse as rapidly in the inner core as it can in the fluid outer core. Only on rare occasions can the thermodynamics, the fluid motion and the magnetic field all evolve in a compatible manner that allows for the original field to diffuse completely out of the inner core so that the new dipole polarity can diffuse in and establish a reversed field.
Many authors have pointed out that the dipole part of the magnetic field has been weakening during historic times, and that if the present trend continues, the dipole field will go to zero in roughly 1500 years. Some people take this to mean that we are entering a reversal. Although this possibility cannot be discounted, many investigators believe that the trend will not continue and that the field will regain its strength, as it has many times in the past.
Geomagnetism
Daily Movement of the North Magnetic Pole
It is important to realize that the position of the North Magnetic Pole given for a particular year is an average position. The Magnetic Pole wanders daily around this average position and, on days when the magnetic field is disturbed, may be displaced by 80 km or more. Although the North Magnetic Pole's motion on any given day is irregular, the average path forms a well-defined oval. The diagram shows the average path on disturbed days.
The cause of the North Magnetic Pole's diurnal motion is quite different than that of its secular motion. If we measure the Earth's magnetic field continually, such as is done at a
magnetic observatory, we will see that it
changes during the course of a day - sometimes slowly, sometimes rapidly. The ultimate cause of these fluctuations is the Sun. The Sun constantly emits charged particles that, on encountering the Earth's magnetic field, cause electric currents to flow in the ionosphere and magnetosphere. These electric currents disturb the magnetic field, resulting in a temporary shift in the North Magnetic Pole's position. The size and direction of this shift varies with time, in step with the magnetic field fluctuations. Since such fluctuations occur constantly, the Magnetic Pole is seldom to be found at its "official" position, which is the position in the absence of magnetic field fluctuations.
Lets compare pole movement and global warming. What do you think we'll find?
Well. Those two graphs either scream correlation or it screams coincidence?
A fool would say coincidence.
The 1982 drop is a dead give a way.
