The earth's magnetic field This might sound like a silly question. Is it possible for the earth's magnetic field to actually destroy or harm earth? (implosion, crushing etc.)
 A: I'd say a big NO for that...
Perhaps, the real truth is that "Without the magnetic field of Earth, we'd face a lot of awful things than just Greenhouse effect & Global warming..."
The magnetic field protects Earth from most of the charged particles (based on Lorentz force) in Cosmic rays and Coronal mass ejections (Not all are deflected away. It just reduces the effect and doesn't prevent it completely). It would've been better if it also protects us from neutrinos..! But, we aren't so lucky that they're neutral...
This paper would be useful for your question...
A: Yes, the Earth's magnetic field can harm things on the Earth. For example, when a large solar flare hits the earth it causes changes in the Earths magnetic field and these changes cause a voltage to be generated in any piece of wire. When those pieces of wire are power cables it can knock out elecricity supplies. See for example this article, though bear in mind newspapers are generally sensationalist and solar flares probably won't end civilisation for a while yet.
However if you're asking from the perspective of a creature less reliant on modern technology, for example an ant, it's pretty unlikely that there's enough energy stored in the Earth's magnetic field to inconvenience you.
As both Crazy Buddy and Michael Luciuk have pointed out, the Earth's magnetic field does an excellent job of protecting us from solar radiation. Without it not only would we all die of radiation damage, but the unchecked solar radiation would strip away the Earth's atmosphere. So the worst damage the Earth's magnetic field could do would be due to it not existing.
