This author, who I've never heard of, has his name take up fully one-half of the book cover! Why? Who knows? The story is really a rip-off of the movie The Core, and both of them have it wrong.
There will be a magnetic pole reversal on Earth and it will cause disruption, but such reversals do not take place overnight. It can take thousands of years, and the worst effects will most likely be to our electronics. We don't need a compass to navigate now we have GPS satellites, but these satellites themselves will be at risk of failing should Earth's magnetic field die - which it will before it grows again after the reversal. For a while we could have several north and south poles at the same time, so even a compass would be useless!
Other than that - and perhaps some increased health risks when cosmic rays are no longer kept out of Earth's biosphere because the magnetism is gone, or is disrupted - we'll be fine, so this book is scare-mongering at best.
This story asks, "When the Earth’s magnetic fields begin to weaken, meteorologist Chapman Boone and his sister, Kristi, recognize signs of a coming apocalypse - and now they must fight to survive… An adrenaline-charged adventure that kicks off a series!" Oh god, another series. Fuck this shit.