Endless Green Decay

Chapter 3: Fires, Chaos, Balance.

The frail nature of humans often leads to unfortunate outcomes, the fight for resources on a decaying Earth led many nations to go to war and with it end the peace of the world.
Many decades of wars and bloodshed already ruined Earth but the real end of it was when the last resort weapons were used, a weapon designed to eliminate all breathable air in the vicinity of the detonation area, but things went horribly wrong as the launching systems malfunctioned and instead of launching only one, all 43 of them launched at the same time everywhere around the globe, not just the targeted area, leading to a total loss of oxigen on the whole Earth lasting for a whole day until the effect of the weapons ceased, it wasn't long enough to kill everything, but it was enough to kill most of the human population.
Pockets of humanity survived for a while but they withered away as lack of food and other resources was prevalent, but the planet, and John somehow endured.
Trees, vegetation started growing, nature was reclaiming and swallowing whole cities turning everything a shade of green most pleasant to the eyes, except there was no one to bask in the sunlight except John, who managed to survive for decades thanks to his body's ability to generate energy from various sources such as sunlight and thermal energy, he did not need to consume food, or water, as his only necessary source of nutrition was the sun.