I would like someone to explain how this supports creationism.
Me too.
Origin of the Earth’s magnetic field
The Humphreys Proposal
Dr Humphreys proposed that God first created the earth out of water.1 He based this on several Scriptures, e.g. 2 Peter 3:5 which concludes that the earth was formed out of water and by water. After this, God would have transformed much of the water into other substances like rock minerals. Now water contains hydrogen atoms, and the nucleus of a hydrogen atom is a tiny magnet. Normally these magnets cancel out so water as a whole is almost non-magnetic. But Humphreys proposed that God created the water with the nuclear magnets aligned. Immediately after creation, they would form a more random arrangement, which would cause the earth’s magnetic field to decay. This would generate current in the core, which would then decay according to Barnes’ model, apart from many reversals in the Flood year as Humphreys’ model states.
Observational support from the fields of other planets
Dr Humphreys also calculated the fields of other planets (and the sun) based on this model. The important factors are the mass of the object, the size of the core and how well it conducts electricity, plus the assumption that their original material was water. His model explains features which are deep puzzles to dynamo theorists. For example, evolutionists refer to ‘the enigma of lunar magnetism’2—the moon once had a strong magnetic field, although it rotates only once a month. Also, according to evolutionary models of its origin, it never had a molten core, necessary for a dynamo to work. Also, Mercury has a far stronger magnetic field than dynamo theory expects from a planet rotating 59 times slower than Earth.
Even more importantly, in 1984, Dr Humphreys made some predictions of the field strengths of Uranus and Neptune, two giant gas planets beyond Saturn. His predictions were about 100,000 times the evolutionary dynamo predictions. The two rival models were inadvertently put to the test when the Voyager 2 spacecraft flew past these planets in 1986 and 1989. The fields for Uranus and Neptune3 were just as Humphreys had predicted.4 Yet many anti-creationists call creation ‘unscientific’ because it supposedly makes no predictions!
Humphreys’ model also explains why the moons of Jupiter that have cores have magnetic fields, while Callisto, which lacks a core, also lacks a field.5 (See Dr Humphreys’ online article Beyond Neptune: Voyager II Supports Creation)
http://creation.com/the-earths-magnetic-field-evidence-that-the-earth-is-young