4C is probably "humans still alive as a species but in incredibly reduced numbers and no functioning large scale modern civilization". At 4C there's not a lot of food that can be produced; heat actually becomes lethal for days at a time in large areas of the world; extreme weather events have become the norm.
4C is probably "humans still alive as a species but in incredibly reduced numbers and no functioning large scale modern civilization". At 4C there's not a lot of food that can be produced; heat actually becomes lethal for days at a time in large areas of the world; extreme weather events have become the norm.