Scientists Have Puzzled Over the Drifting North Magnetic Pole for Years – Now, Some Answers
Unlike our geographic north pole, which is in a fixed location, magnetic north wanders. This has been known since it was first measured in 1831, and subsequently mapped drifting slowly from the Canadian Arctic towards Siberia. However, since the 1990s, this drift has turned into more of a sprint – going from its historic wandering of 0–15 km a year to its present speed of 50–60 km a year. Credit: N. GilletMagnetic North and the Elongating Blob
For some years now, scientists have been puzzling over why the north magnetic pole has been making a dash towards Siberia. Thanks, in part, to ESA’s Swarm satellite mission, scientists are now more confident in the theory that tussling magnetic blobs deep below Earth’s surface are at the root of this phenomenon.
Unlike our geographic north pole, which is in a fixed location, magnetic north wanders. This has been known since it was first measured in 1831, and subsequently mapped drifting slowly from the Canadian Arctic towards Siberia.
However, since the 1990s, this drift has turned into more of a sprint – going from its historic wandering of 0–15 km a year to its present speed of 50–60 km a year. This shift in pace has meant that the World Magnetic Model has had to be updated more frequently, which is vital for navigation on smart phones, for example.
Our magnetic field exists because of an ocean of superheated, swirling liquid iron that makes up the outer core. Like a spinning conductor in a bicycle dynamo, this moving iron creates electrical currents, which in turn generate our continuously changing magnetic field.
Numerical models based on measurements from space, including from ESA’s Swarm mission, have allowed scientists to construct global maps of the magnetic field. Tracking changes in the magnetic field can tell researchers how the iron in the core moves.
The magnetic field and electric currents in and around Earth generate complex forces that have an immeasurable impact on every day life. The field can be thought of as a huge bubble, protecting us from cosmic radiation and charged particles that bombard Earth in solar winds. Credit: ESA/ATG medialab
During ESA’s Living Planet Symposium last year, scientists from the University of Leeds in the UK reported that these satellite data showed that the position of the north magnetic pole is determined largely by a balance, or tug-of-war, between two large lobes of negative flux at the boundary between Earth’s core and mantle under Canada.
Following on from this, the research team has recently published their latest findings in Nature Geoscience is a monthly peer-reviewed scientific journal published by the Nature Publishing Group that covers all aspects of the Earth sciences, including theoretical research, modeling, and fieldwork. Other related work is also published in fields that include atmospheric sciences, geology, geophysics, climatology, oceanography, paleontology, and space science. It was established in January 2008. " class="glossaryLink ">Nature Geoscience.
Phil Livermore, from the University of Leeds, said, “By analyzing magnetic field maps and how they change over time, we can now pinpoint that a change in the circulation pattern of flow underneath Canada has caused a patch of magnetic field at the edge of the core, deep within the Earth, to be stretched out. This has weakened the Canadian patch and resulted in the pole shifting towards Siberia.”
The big question is whether the pole will ever return to Canada or continue heading south.
Using satellite data, including from ESA’s Swarm mission, researchers have concluded that this is down to competition between two magnetic blobs on the edge of the Earth’s outer core. Changes in the flow of molten material in the planet’s interior have altered the strength of the above regions of negative magnetic flux. The image shows how the strength of the magnetic patch over Canada has weakened and how the position of the north magnetic pole has changed between 1999 and 2019. Credit: P. Livermore
“Models of the magnetic field inside the core suggest that, at least for the next few decades, the pole will continue to drift towards Siberia,” explained Dr. Livermore.
“However, given that the pole’s position is governed by this delicate balance between the Canadian and Siberian patch, it would take only a small adjustment of the field within the core to send the pole back to Canada.”
Reference: “Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation” by Philip W. Livermore, Christopher C. Finlay and Matthew Bayliff, 5 May 2020, Nature Geoscience.
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