Prelims Level
Mains Level

Why in news?

  • Rapid shifts in the Earth’s north magnetic pole are forcing researchers to make an early update to a model that helps navigation by ships, planes and submarines in the Arctic.

Shifting Magnetic North Pole:

  • Magnetic North Pole wanders, and every few hundred thousand years, the polarity flips so that a compass would point south instead of north.
  • Liquid churning in Earth’s core generates most of the magnetic field, which varies over time as the deep flows change.
  • However, the magnetic field has been changing so quickly and erratically that while conducting a routine check in early 2018, British and US researchers realized drastic steps were needed.
  • The shift they observed was so large it was on the verge of exceeding the acceptable limit for navigation errors.
  • Scientists must periodically update the World Magnetic Model to map this process, and the most recent version – produced in 2015 – was intended to last until 2020.

Tracking the movement:

  • The wandering pole is driven by unpredictable changes in liquid iron deep inside the Earth.
  • It’s moving at about 50 km (30 miles) a year.
  • It didn’t move much between 1900 and 1980 but it’s really accelerated in the past 40 years.
  • On the contrary, the South magnetic pole drift is very slow (less than 10 km per year).
  • It has not changed much over the past few decades, and hence provided a much smaller contribution to the overall model declination error.

What causes the Drift?

  • The Earth’s magnetic field is in a permanent state of change.
  • Magnetic north drifts around and every few hundred thousand years the polarity flips so a compass would point south instead of north.
  • The strength of the magnetic field also constantly changes and currently it is showing signs of significant weakening.

Effect on Life:

  • Life has existed on the Earth for billions of years, during which there have been many reversals.
  • There is no obvious correlation between animal extinctions and those reversals. Likewise, reversal patterns do not have any correlation with human development and evolution.
  • It appears that some animals, such as whales and some birds use Earth’s magnetic field for migration and direction finding.
  • Since geomagnetic reversal takes a number of thousands of years, they could well adapt to the changing magnetic environment or develop different methods of navigation.

Effect on Climate:

  • Earth’s magnetic field, which has existed for at least 3.45 billion years, provides a shield from the direct impact of solar radiation. Even with Earth’s strong magnetic field today, we’re still susceptible to solar storms that can damage our electricity-based society.
  • The fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.

World Magnetic Model:

  • The World Magnetic Model (WMM) is a large spatial-scale representation of the Earth’s magnetic field. It consists of a degree and order 12 spherical harmonic expansion of the magnetic potential of the geomagnetic main field generated in the Earth’s core.
  • The charts are used to convert between compass measurements of magnetic north and true north. It can be found in the navigation systems of ships and airplanes as well as geological applications (such as drilling and mining).
  • Researchers from the U.S.’s National Oceanic and Atmospheric Administration (NOAA) maintain the WMM.
  • The charts, known as the World Magnetic Model (WMM), are used to convert between compass measurements of magnetic north and true north
  • The WMM is also part of map applications in smartphones, including the Google Maps App.
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