Geologist Gregg Braden has made the claim that the Earth’s magnetic field has dropped 38% (measured in magnetometers) in the past two thousand years (about 1.9% per century), and the rate of decline has risen to 6% in the past century. Basically, the global magnetic field is dropping at an accelerating rate toward zero point, at which time the polarity of earth will reverse. It is unknown whether the decline of the magnetic field will continue to increase. The magnetic field last flipped 780,000 years ago, but the time between reversals has varied from a few thousand years to 35 million years. During this time additional magnetic poles could appear in the weakening field. A compass then would point in different directions depending on the location. Then the magnetic field would almost completely disappear for several thousand years before re-emerging in the opposite direction.
The effects of this reversal are hard to predict. Some theorists claim that it will not have any effect on humans. With the modern reliance on electricity and electromagnetic effects (radio, satellite communications, GPS), the world will have technological disruptions in the event of a full field reversal. One effect that may occur during a magnetic reversal is that the Earth may not be protected from charged particles streaming from the sun. These particles are called the solar wind, and could be dangerous to life if they reached the Earth’s surface. The amount of radiation reaching the surface of the Earth would definitely increase, but not by much. More people would suffer skin cancer, but we would not all die horribly from radiation poisoning.