The planet’s magnetic field flips?north becomes south and vice versa?on average every 300,000 years. However, the actual time between reversals varies widely. The field last flipped about 800,000 years ago, according to the geologic record. Since 1840, when accurate measures of the intensity were first made, the field strength has declined by about 5 percent per century. If this decline is continuous, the magnetic field could drop to zero and reverse sometime within the next 2,000 years. – Natlgeo
What was going on 800,000 years ago? The Chinese* Used Hand Axes for one. (* Pretty misleading statement since there was no China at that time and this was Homo erectus, not Homo sapiens.) According to the BBC, 10,000 years after that, humans mastered fire. (* Again, Homo erectus.) The first creation and use of stone tools by hominids appears around 2.5 million years ago in the archaeological record.? The most accepted view among anthropologists is that our species, Homo sapiens, originated in the African savanna as early as 250,000 years ago. So, no “modern human” has ever witnessed or survived a reversal of the Earth’s magnetic field.
Since the magnetosphere shields the surface of the Earth from the charged particles of the solar wind, will all life on Earth be fried in as the shields drop? Wiki says this:
“Some speculate that a greatly diminished magnetic field during a reversal period will expose the surface of the earth to a substantial and potentially damaging increase in cosmic radiation. However, homo erectus and their ancestors certainly survived many previous reversals. There is no uncontested evidence that a magnetic field reversal has ever caused any biological extinctions. A possible explanation is that the solar wind may induce a sufficient magnetic field in the Earth’s ionosphere to shield energetic particles even in the absence of the Earth’s normal magnetic field…”