The demise of human civilization was set in motion by the industrialized age. The dense energy contained in fossil fuels made it possible to produce more food for more people, so the human population expanded well beyond the planet’s carrying capacity. The problem was, everything needed to sustain the population was finite. As fuel and natural resources were used up, famine and pandemics ensued. Climate change eradicated ecosystems. Global shortages led to resource wars. The collapse of civilization came with epic suffering and predatory behavior.
Without fossil fuels to power vehicles and without materials to build with, transportation ended. Animals that could have been useful were eaten. The only humans that survived did so by establishing outposts in remote areas so difficult to get to, nobody tried. They were safe.
Satellite communications ended when power grids collapsed and trajectories could no longer be controlled. Chain reaction collisions reduced any satellites in orbit to rubble. The last means of communication sponsored by what was left of central government involved raising antennas by hydrogen dirigibles to facilitate short wave radio communications. Eventually all communication ended. The last outpost, known as Zerodrome floated their antenna for years after the last communication was heard, hoping to hear from others to no avail.