Earth’s Magnetic Field

Earth’s magnetic field, albeit generated approximately 2,000 miles below the surface, protects the planet’s atmosphere from space radiation and solar wind. It is essential, then, for life. The strength of the magnetic field, though, is rapidly decreasing; in the past 300 years alone, its strength has diminished by 10%. By first exploring what the magnetic field is and where it comes from, this film is able to postulate reasons for this rapid decline as well as the potential effects of it. The proposed ideas rely heavily on expert opinions, computer simulations, and physical models.

The magnetic field operates as a feedback loop; the combination of magnetism, heat and motion in the Earth’s core creates an electrical current. This current leads to more magnetism, which then leads to stronger electrical currents, and so on. Ultimately, this complex process creates the overall magnetic field. Due to its magnetism, the field deflects charged particles away from the Earth, thus acting as a shield from solar radiation. Without it, the atmosphere would be slowly stripped away and all life-forms would be exposed to deadly radiation. The magnetic field, then, is part of what makes life on Earth sustainable. Having a magnetic field, though, does not make Earth unique.

Magnetic volcanic rock found on the surface of Mars demonstrates that, until about 4 billion years ago, Mars also had a magnetic field. Its core, however, cooled and solidified, therefore halting the motion that enabled its magnetic field to exist. Because there was no longer a “shield” protecting it, Mars’s atmosphere was stripped away by solar winds. This process suggests that if Earth’s magnetic field were to dissipate, for similar or different reasons as Mars’, the planet would also lose its atmosphere and, consequently, the life that it sustains. Today, scientists can tell that the strength of Earth’s magnetic field is decreasing by analyzing substances such as volcanic rock and clay pottery. When cooled, magnetic particles in such substances align with the magnetic field. These particles, then, denote the strength of the field at the time of cooling as well as the direction of it: that is, where the geomagnetic poles were located at the time of cooling. These analyses depict that it is relatively common for the strength and direction of the magnetic field to fluctuate; current estimates suggest that, on average, the direction of the magnetic field switches every 200,000 years.

The strength of the magnetic field can indicate when there will be a reversal of the geomagnetic North and South poles. The field is often weak when patches of anomalies are prominent. (Anomalies are local variations in the magnetic field where the polarity of it are opposite to what it is assumed to be based on location). These variations cancel out the polarity of the magnetic field, therefore decreasing its strength. The anomalies will eventually begin to connect, creating larger and larger anomalies until the polarity of the entire magnetic field flips. It is possible, then, that the current rapid decline in magnetic field strength the Earth is experiencing is because the Earth’s magnetic field will reverse (relatively) soon. Because of this weakening, more radiation is reaching Earth’s inhabitants, therefore increasing occurrences of skin cancer . Similarly, the anomalies are currently affecting navigation, as will the reversal.

On the bright side, though, the Aurora will potentially appear in nontraditional places, causing a nice change of scenery. It is interesting that no anthropogenic causes were discussed in this film. Typically, when rapid changes are occurring on the Earth, it is the direct result of human action. The film, then, serves as a reminder that Earth is truly dynamic.