Such external costs should only be included if the uncertainties on estimates of external costs of CO2 emissions are somehow represented. And I’m referring to factoring in all structural and parametric uncertainties inherent in climate models. Cutting to the chase, you can never factor in, or even meaningfully bound, those structural uncertainties. Not a big deal for million dollar investments, a big deal for trillion dollar investments.
Modelers of all ilks generally avoid reporting the underlying uncertainties in their results. And when they do report them, they are woefully underestimated. Fine in the abstract, but not acceptable when trillions of dollars are at stake. Dollars that can be spent instead on direct low risk, high impact improvements in third world child health (clean air, clean water, infectious diseases, etc.). Maybe choose those that also mitigate climate impacts (as we currently understand them), but directly save the living children/people first.
Keep on improving the models with scientific research, but don’t fool ourselves about the accuracy and completeness of such models for policy analysis. I’m old enough to remember the Club of Rome/Limits to Growth controversies.
The geophysics behind, say, the Santos Barrossa gas project appears pretty tight; the C02 emmissions estimates are directly tied to the economic feasibility estimate process .. if one is wrong then so is the other, if so it must be a bad investment and a foolish project?
When the project’s offshore and gas processing emissions are factored in, the LNG produced from the Barossa field would have a total emissions intensity of 1.4 tonnes of CO2 per tonne of LNG produced.
This makes the Barossa development the most emissions intensive LNG projects in Australia and the world
At this point in time there's a clear understanding of the consequences of the current 11 billion tonne of CO2 equivilant emmissions released annually .. an increase in trapped solar heat energy that directly leads to increased storm intensity, climbing global mean tempretures, and edging closer to positive feedback thresholds which are significantly hard to reverse when crossed.
Without. But on a global scale those externalities aren't priced in. Particularly at the margin.