Sunday, September 7, 2014

Changing Earth Magnetic Field and Moving North Pole

When we use a compass, we may assume that the Earth's magnetic field is a constant, and therefore, our compass readings are always accurate.  Well, it seems that this is not exactly true.

Scientists world-wide are studying the Earth's magnetic field.  The webpage, reports that a series of three satellites was launched in November 2013 by the European Space Agency.  The purpose of these Swarm satellites is to provide new insights into the workings of Earth’s global magnetic field, which is generated by the motion of molten iron in Earth’s core.  It is important to understand whether there are changes because the magnetic field protects our planet from cosmic radiation and charged particles emitted by our Sun. It also provides the basis for navigation with a compass.

Based on data from Swarm, the above image shows the average strength of Earth’s magnetic field at the surface (measured in nanotesla) between January 1 and June 30, 2014.

The second image below shows changes in that field over the same period. Though the colors in the second image are just as bright as the first, note that the greatest changes were plus or minus 100 nanotesla, a minuscule but still detectable change in a field that reaches 60,000 nanotesla.

Geophysicists have noted that the strength of Earth’s magnetic field has been decaying—about 5 percent globally over the past century. However, it is not changing in a uniform way; it grows growing stronger in some places and weaker in others.

The changes are a natural variation due to processes in the deep interior of the Earth, explained Nils Olsen, a Swarm team member from the Technical University of Denmark. The movement of molten iron in the core creates electric currents, and changing electric currents create a magnetic field. So every change in the flow of the iron core means changes in the magnetic field.

“The magnetic field changes in a chaotic manner, and we do not know why it changes in the way it does nor how it will evolve in the future,” said Olsen. “There is no periodic behavior, and it is therefore rather difficult, if not impossible, to predict how the magnetic field evolves over time. We can just observe how it has changed in past and what it looks like today.”

One thing that scientists have realized is that the position of the magnetic north pole not only shifts, but that the rate of movement is increasing.  The video above shows how the north pole has moved over the last 400 years.  According to the webpage ,  the shift in the pole's position is increasing.

After transferring 420 years of north pole position data from the NOAA Geo Data Center, configuring it to fit in an Excel spreadsheet, adding a complicated formula to determine exact distance between 2 sets of latitude-longitude coordinates, applying the formula to each data point in the series, and then finally plotting it all in a visual graph, it is alarming to discover the amount of magnetic pole shift – just over the past 10 to 20 years.

Since 1860, the magnetic pole shift has more than doubled every 50 years.

During the past 150 years, the pole shift has been in the same direction.

During the past 10 years, the magnetic north pole has shifted nearly half of the total distance of the past 50 years! In other words, the pole shift has apparently sped up substantially.

Pole Shift has more than doubled each of the last 50 years


The graph above shows changes in the rate of pole shift.  The present rate of magnetic north pole shift is about 55 kilometers per year. According to the data set, during the year 2000 the magnetic north pole actually shifted more than 70 kilometers.

The issue now is, since the pole shift has been at 400 year record high rates during the past 10 to 20 years, the cumulative effect is now beginning to cause real-world issues.
Will the effects affect us noticeably or in a bad way? Time will tell I suppose, but at the current rate there will no doubt be direct effects on many systems in the years ahead,
It is not known if the shift will speed up or slow down in the years ahead. Some say that a pole reversal is overdue, and this phenomenon may be indicators of the beginnings of that process. 

According to the webpage ,A geomagnetic reversal is a change in Earth's magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth's field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was the opposite. These periods are called chrons. The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years, with an average of 450,000 years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago. A brief complete reversal, known as the Laschamp event, occurred only 41,000 years ago during the last glacial period. That reversal lasted only about 440 years with the actual change of polarity lasting around 250 years. During this change the strength of the magnetic field dropped to 5% of its present strength.  The fact that the poles have reversed was first discovered in the early 20th century when geologists first noticed that some volcanic rocks were magnetized opposite to the direction of the local Earth's field. However, it was not until the 1950s that scientists gathered enough data to gain a fuller understanding of this phenomena.   A NASA diagram of what the reversal would look like is below.

Note that the earth’s magnetic field is what protects us from radiation. Without it, we would not survive. Could a pole reversal cause a period of time in-between flip-flop such that we would be exposed to deadly radiation? Stay tuned…


European Space Agency/Technical University of Denmark (ESA/DTU Space). Caption by Mike Carlowicz.

No comments:

Post a Comment