Originally Posted by Kareeah_Indaga
I think this came up in a previous thread but there should be a huge crime wave shortly after the Snap, both as people realize a large number of cars, houses, etc. are now unoccupied and that things like food, medicine, gasoline etc. are going to be badly disrupted for a while.
Definitely so. There will be widespread looting and hoarding starting immediately afterward, together with panic buying from whatever stores are still open. With only half the number of police, most areas will be helpless to stop it for days or weeks, and this will merge with the broader wave of other crimes

And there will be a whole spectrum of armed gangs, some of them criminals from the outset and others attempting to form neighborhood patrols. On a local level, I would expect a few of the better-prepared groups to take over warehouse stores like CostCo and Sam’s Club, since those have enough food on-site to keep a gang going for some time. And all the surviving disaster preppers will be hunkered down saying “I told you so.”

At some point, the government will try to reassert itself with martial law, but that could take quite a while. Simply moving troops around will be a major challenge, since most highways and city streets will probably be cluttered with abandoned vehicles, and the military will have half the normal personnel for flying, fueling and repairing their aircraft. The first few weeks or months will be chaos writ large, and I wouldn’t expect anything near government control for at least a year—and I wouldn’t be surprised if there were still small-scale warlords and gang enclaves in pockets everywhere, especially in the larger cities, persisting for years. And of course there will be any number of lunatics, nutbars and fringe groups proclaiming their own republics and/or the end times.

Originally Posted by Kareeah_Indaga
Unrelated, one thing I’m wondering about is the dust from all the Snapped. If it just gradually fades out of existence, that is a LOT of mass taken out of the biosphere, if it sticks around it should be screwing with the weather at least in the short term (haze, dust storms) even ignoring any effects it might have on, say, soil productivity.
That’s an extremely good point about the missing biomass. Vertebrate biomass is negligible on a global scale, but plant biomass is a different story.

Losing 225 gigatons of carbon from global ecosystems is significant, but losing the transpiration from that much vegetation could have even greater effects on local weather and hydrology. Beyond that, plant leaves reflect most of the sunlight they intercept, so with 50% of vegetation cover removed, it would mean that much more sunlight absorbed by bare earth and reradiated as infrared, so we could see an immediate sharp rise in global temperatures. Among many other things, that means even more accelerated melting of glaciers, snow cover and permafrost, plus even greater fire risk, as well as increased spread of tropical diseases and a correspondingly greater chance of a pandemic—although in this context, the likely breakdown of international travel may slow its spread or even help contain it.

And speaking of soil productivity, losing half of all earthworms, nematodes, thrips and other soil organisms might cross some threshold and cause a crash in whatever crops remain. To say nothing of the loss of half of all water-filtering organisms, right when soil erosion and runoff will be increasing tremendously.