You really should read through Exxons internal documents that have been disclosed as part of this process. They far exceed what you are describing in terms of uncertainty. Not only did they conduct a mini IPCC to evaluate the public science they conducted their own original research. Then based on all of this they drew up operational plans for the effect on their Arctic operations.
I have read them. These was the theoretical work of a handful of geoscientists working from the computational limitations of 70s-80s technology, and substantially limited data compared to what has been made available in the decades since.
The historic certainty of climate change is being vastly overstated, neglecting the critical role that petroleum has played in the development of modern infrastructure and society in a blind rush to find some evil to blame. Science is built on skepticism.
