1. Anthropogenic (man released) CO2 is a major component of climate warming
2. CO2 sensitivity must be high enough
3. CO2 effects must not dampen out too fast (i.e. logarithmic instead of exponential curve for CO2 effect)
4. The net of atmospheric feedback effects must be durably overcome by CO2
5. Anthropogenic warming effects must be more expensive to adjust to than to prevent.
6. The discount rate for time preferences between now and 2100 must not exceed a certain value
7. Investment now in economic growth will not yield so much value that it's a superior use of funds over reallocating the resources to global warming prevention.
8. Technology will not change enough in the next 90 years to sufficiently change the costs to make waiting and managing the effects the more prudent course.
9. Purposeful planning on large scales and over decades will not suffer the sort of deviations en route that made a pathetic mockery of Soviet 5 year plans.
This list is not exhaustive. I'm omitting, for example, the issue of focusing adjustments exactly in the areas where purchasing power parity (PPP) indicates the money is least effective.
Every single one of these nine points has challengers. The amount of work proving points 8 and 9 are so minimal as to be laughable. It's just assumed to be justifiable as if we haven't had a century of data saying that the problems of long term state planning and government economic distortion are large and largely unsolvable, to a great extent because technology surprises require faster shifts than governments are capable of.
Every time I hear "the science is settled", it's invariably about points earlier up in the chain which establish that there's some sort of problem but do nothing regarding picking out a policy choice. But the policy choices among the warmists are settled at least as much as they view the climate science as settled.
All those policy choices were made without going through the actual trouble of establishing any of the basic economic groundwork. We're all supposed to acquire historical amnesia about economics. This magical rehabilitation of state solutions justifies permanently moving 1% of global economic product into the service of handling climate change for the next nine decades (the Stern Report's recommendation). It is a fantastic sum to be thrown at a problem using a methodology that is known bad.