At 4C of warming the feedback loops of Earth begin to accelerate at an unprecedented rate, the economy is irrelevant from this point onwards.
Just one of these feedback loops has more CO2 equivalent than over 60% of anthropogenic emissions since the industrial revolution.
At 4C of warming the human race is due for extinction unless through its self perceived exceptionalism it somehow manages to circumvent the laws of thermodynamics.
The alternative is we start building a better tomorrow TODAY.