The Earth of timeline Lucifer-3 (B528, IW134) was sterilized by a supernova or gamma ray burster (GRB) in 1979. As of 2004, it was being "systematically" looted by Homeline. This description seems to imply that survivors (if any) are not significant in numbers or organization. I'm curious as to what might have transpired between the first indication of trouble and the final collapse of the ecosystem (and civilization along with it).
Although it seems reasonable to pin the divergence point to the
March 5th Event, it doesn't really matter all that much. If so, it would mean that the offending burst of radiation came in from almost due south over Antarctica, in the autumn of the southern hemisphere.
The initial burst was probably powerful enough to knock out most spacecraft, due to secondary radiation effects from structural components.
The "sterilizing" effect of a supernova or GRB is largely due to the destruction of the ozone layer and subsequent influx of solar UV, rather than direct radiation received at ground level. Although the initial ionization products are confined to the hemisphere facing the supernova or GRB, they are rapidly (~60 days) carried around the globe and more slowly across the equator. Interestingly, some of the ionization products screen out the visible frequencies that drive photosynthesis: the sky could darken at the same time the UV spikes.
As the UV flux rises, plants on the surface start dying; the darkness hastens the process. Animals can presumably shelter during the day, but with their food sources cut off they begin to die as well. Eventually, every living thing in the first few inches of soil and first few feet of water is dead. By the mid-1980s, lightning-induced forest fires will burn out most of the standing dead wood around the globe, adding carbon dust and ash to the disaster.
Humans will notice when their satellites go offline, but they may be slow to react to the full scope of the disaster. Environmental concerns about the ozone layer have only been in the public consciousness for a few years at this point, and the science behind it is relatively new and uncertain. The phrase "
nuclear winter" hasn't been coined. In the end, though, world-wide crop failures will signal the need to Do Something.
At this point, I'm interested in hearing what others think that Something would be. Panic, naturally, and some degree of fighting over remaining stores of food followed by starvation and disease, but does this occur at local, regional, or national levels? Humans, too, could survive by becoming nocturnal, and might even grow a few crops indoors -- as long as the lights stay on. Is this even possible? Ozone levels won't recover for at least 50 years, and then the replanting is only beginning -- what would it take to hold on that long? What would that effort leave behind for Homeline to loot?