Coal, oil, and gas, all three need to be stopped. They are the bulk of the problem, but not all of it; we also need to end some industrial chemicals like SF₆ stop deforestation, and sharply reduce methane production in agriculture.
Cold turkey will kill a lot of people as existing food systems depend on fossil fuels for everything from nitrate fertilizer manufacturing to food delivery.
A managed phase-out is far preferable because of that.