Most people aren't overly concerned with Sun Spots and Solar Flares. In fact I'll bet a lot of people have never even heard of them. Because Sun Spots & Solar Flares aren't as sensationalized as some of the other potentially cataclysmic events such as an asteroid strike, pole shift, super volcano eruption etc. Unfortunately, unlike the aforementioned catastrophes, Sun Spots and Solar Flares happen regularly. They can, and they do, wreak havoc with the Earth. The results just aren't as dramatic, and in fairness, at least so far, aren't as catastrophic.
What exactly are Sun Spots and Solar Flares?
A Sun Spot is a storm on the surface of the Sun that is cooler than the surrounding material. The cooler temperature results in increased magnetic activity that allows charged particles to escape from the Sun's atmosphere. These particles are called a Solar wind.
Sun Spots normally occur in seasons of 11 year cycles. The new cycle, which was supposed to begin in 2009 has just recently begun.
The primary effect of Sun Spots on the Earth is on the very upper part of our atmosphere (Ionosphere.) The particles in the solar wind can interact with atoms in the Ionosphere and create problems with communications systems such as background static in data transmitted from satellites and destruction of GPS data. In extreme circumstances, high levels of solar wind can bring about a solar storm where large quantities of charged material is sent into the earth's atmosphere. Although this material is not physically dangerous, it does cause the Ionosphere to swell in response to extra heating. The swelling can promote the decay of satellites in the Earth's lower orbit.
Overall not all that dangerous. However, the Solar Flares that emanate from the Sun Spots are a different story. The biggest Sun Spots generally create the most intense Solar Flares.
A Solar Flare is defined as a sudden, rapid, and intense variation in brightness. The amount of magnetic energy released from a Solar Flare is the equivalent of millions of 100 megaton hydrogen bombs exploding at the same time. As the magnetic energy is being released, particles, including electrons, protons and heavy nuclei, are heated and accelerated into the Solar atmosphere. This energy is ten million times greater than the energy released from a volcanic eruption, but is also less than one-tenth of the total energy emitted by the Sun every second.
What are the consequences of this "extra Solar energy" on the Earth? The precise effects are hard to determine. In the short term the aftermath usually involves disruption of ALL FORMS OF ELECTRONIC COMMUNICATIONS with a severe threat to all space satellites and telecommunications. The long term effects are not easy to categorize either, but they probably include highly disturbed weather patterns with a greatly increased risk of earthquakes and volcanic eruptions in vulnerable locations.
There is some evidence to support the theory that Solar Flares can have intense medical and emotional consequences on human beings. On a larger scale, research shows that solar activity has the POTENTIAL to trigger general social unrest including wars, riots revolutions, and a deteriorating state of International harmony.
So...could a Solar Flare actually destroy life on Earth? The potentially troubling answer is...Yes. Although the Sun is remarkably stable, it does go through phases of increased activity. It is believed (theory) that a lethal Solar Flare explosion could conceivably erupt at any moment. The fact that we haven't seen one for many thousands of years means nothing. An extreme flare-up could happen before this sentence is finished.
From a survival perspective, should we be concerned about Sun Spots and Solar Flares? The short and easy answer is no. A Solar Flare is no different than any of the other natural events that COULD happen. There's nothing we can do to prevent it from happening. However, we can prepare to survive one IF we choose to believe a Solar Flare of sufficient size and power will occur that will threaten our existence. Is it possible? Yes? Is it probable? No one knows for sure.
Probability in our lifetime: Unknown
Danger if prepared: 4-6 (long term-but not from the flare itself}
Danger if unprepared: 7-8 (long term-but not from the flare itself)