Doomsday: Sunfury

Earth is humanity’s cradle, but by no means can it completely harbour us from harm. Many risks threaten individual lives, but there are some catastrophic enough to wipe out entire species. Is it possible for the prolific human species to face extinction?

The Sun provides all living things with the heat (and, indirectly, food) needed to survive. Yet for all its needed sustenance, there are also times when it turns against life, in particularly spectacular fashion. Every 13 years it throws a tantrum of sorts, with the next one due on late 2012.

History
The Sun cycles between low and high radiance every 13 years. A particularly famous high point was reached in 1859, when its output caused particularly strong auroræ advancing unusually close to the Equator. It also played havoc with the telegraph technology of the time, shocking operators, causing fires and powering the lines without human-generated electricity.

Power grids are similarly vulnerable to these events. Another (less severe) one in 1989 fried the power grid of Quebec in Canada, leaving 6 million people without power.

Shields up, Scotty

The Earth's magnetosphere.

The Earth generates its own magnetic field (a magnetosphere) from the flow of molten iron and nickel in its core. This helps deflect many of the magnetically charged particles that approach Earth from outer space.

Any magnetic field line originates from the north pole of the magnet and arcs across empty space to the south pole. Because of the donut shape of the magnetic field, it is weakest at the poles. Charged particles find it easier to penetrate the Earth's magnetosphere at the poles, and where they collide with the molecules in the air, the energy is released as auroræ.

Mass ejection
By far the largest source of charged particles (from space) is the Sun. It is continuously releasing its matter (charged from the extreme heat) in a stream of solar wind. As the magnetosphere repels these particles, the solar wind shapes the magnetosphere into a teardrop shape.

The Sun undergoes a solar cycle of approximately 13 years where it changes between low (solar minimum) and high (solar maximum) activity. During a solar maximum, the Sun may eject a particularly large, fast-moving cloud of matter in a coronal mass ejection (CME). One that hits the Earth gives the magnetosphere a run for its money:

• Such an impact is strong enough to shift magnetic field lines. When this happens, electric currents are induced in anything long and metallic (like power lines); where one happens to run into a transformer, the excessive current can make it overheat and melt.
• All electronic equipment are sensitive to strong current. Orbiting satellites enjoy a magnetosphere strength weaker than the one on the ground, and may end up being fried from the charged particles of a CME.

The Sun is expected to reach a solar maximum during late 2012.

Reversed polarity
The Earth's magnetosphere randomly experiences geomagnetic reversals, where the north and south poles switch places. This event is preceded by a weakening of the magnetosphere, during which charged particles can more easily penetrate to the ground. Should a weak magnetosphere coincide with an earthward CME, the effects to life could be disastrous.

The Earth's magnetic field without influence by solar wind. The north end of a compass needle will point to the physical south pole (magnetic north pole).

Scientists have observed a gradual weakening of the magnetosphere, as well as the South Atlantic Anomaly (a spot in the south magnetic pole half of the Earth where there actually are north magnetic pole-pointing field lines). This may suggest that the magnetosphere is due for a weakening and reversal.

Consequences of a coronal mass ejection

• Loss of electrical power, possibly for several years
• Fried electronics
• Crippled communication networks
• Radiation sickness, depending on altitude
• Eye cataracts, depending on altitude

Conclusions

• 2012-compatible? Yes
• Will the world end with a bang or whimper? Whimper
• Armageddon or Ragnarok? Armageddon during an extreme summer, Ragnarok during an extreme winter

Bibliography

• 2012 Apocalypse 2009, television program, Discovery Channel.
• Naked Science: Earth's Invisible Shield 2008, television program, National Geographic Channel.
• Storm Worlds: Cosmic Fire 2010, television program, National Geographic Channel.

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