If we want to keep total global warming smaller than 2oC (or 3oC, or some other chosen value) what is accurate?

The chosen limit on warming in turn sets a limit on how much more fossil fuel we can burn and emit the CO2 to the air, but this limit on fossil fuels depends a little on how much methane and soot we release

The chosen limit on warming sets a limit on how much soot and methane we can release, but doesn't really affect how much fossil fuel we can burn and emit the CO2 because most warming is caused by soot and methane

The chosen limit on warming doesn't affect how much fossil fuel we can burn and emit the CO2, because we will run out of fossil fuel long before the warming reaches 2oC

The chosen limit on warming doesn't affect how much fossil fuel we can burn and emit the CO2, because fossil fuels can't cause any warming at all

The chosen limit on warming sets a limit on how much corn we can grow, because it is the main cause of global warming.