Will Compasses Point South? brings back another doomsday scenario:
The collapse of the Earth’s magnetic field, which both guards the planet and guides many of its creatures, appears to have started in earnest about 150 years ago. The field’s strength has waned 10 to 15 percent, and the deterioration has accelerated of late, increasing debate over whether it portends a reversal of the lines of magnetic force that normally envelop the Earth.During a reversal, the main field weakens, almost vanishes, then reappears with opposite polarity. Afterward, compass needles that normally point north would point south, and during the thousands of years of transition, much in the heavens and Earth would go askew.
A reversal could knock out power grids, hurt astronauts and satellites, widen atmospheric ozone holes, send polar auroras flashing to the equator and confuse birds, fish and migratory animals that rely on the steadiness of the magnetic field as a navigation aid. But experts said the repercussions would fall short of catastrophic, despite a few proclamations of doom and sketchy evidence of past links between field reversals and species extinctions.
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Even if a flip is imminent, it might take 2,000 years to mature. The last one took place 780,000 years ago, when Homo erectus was still learning how to make stone tools.
I hear that the dinosaurs had an advanced civilization — until the poles flipped.