Earth is constantly bombarded by the solar wind, a fully ionized, 1,000,000°C plasma, which, fortunately for humanity, is deflected safely around and past our planet by the geomagnetic field, Earth’s shield. Recent advances in understanding geophysical data, the deep interior of Earth, and the generation of the geomagnetic field now point to the impending end of Earth’s shield. Although the timeframe is uncertain, the demise of the geomagnetic field raises the prospect of global catastrophic peril of unprecedented magnitude. At that point in time, megaengineering approaches may offer the best hope for humanity’s survival. In this chapter, I review the nature of our protective geomagnetic field with particular emphasis on recent concepts pertaining to a natural nuclear fission reactor at the center of the Earth, the georeactor, as its energy source and production mechanism. Evidence is presented indicating the impending exhaustion of the georeactor’s uranium fuel, portending the final demise of the geomagnetic field. Occasional intense solar wind episodes, which overwhelm the geomagnetic field, give tiny glimpses of what can be expected on a grand scale as the georeactor runs out of fuel and the geomagnetic field ultimately collapses. With that warning as to what is to be expected, megaengineering project suggestions are put forward to utilize solar-wind induced electrical current to power electromagnetic shields to safeguard the human population.