Question: What would happen if the whole shield was to break down?

Martin Archer answered on 14 Mar 2013:

Earth’s shield is due to it’s magnetic field. It’s had this for billions of years and whilst its strength changes this is usually over millions of years. So you don’t have anything to worry about. However, if it were to disappear it would have massive effects on us. Firstly loads of our satellites would become useless due to the increased radiation. We would just about survive but the risk of skin cancer and the like would be massive so you’d have to stay out of the Sun. Plus the risk due to solar storms would be massive. In the long term we’d be screwed and Earth would become a barren wasteland like Mars (which had a magnetic shield but lost it somehow).