Read up some more. The magentic field around Earth only blocks about 30% of the incoming radiation.
Plus, every few hundred thousand years, the field reverses. We are already over do for a field reversal and there are signs we are already in the early stages of one. The magnetic north has been increasingly wandering and the field is starting to fluxuate a bit more. A reversal isnt going to happen over night though, it will take a few years. Its not really known the exact number, but it could take up to a couple thousand years(at most anyway) for a pole reversal to finish taking place; thats finishas in starting at full strength, reversing, then coming back to full strength.
To climb the mountain, you must believe you can.