The calculation assumes that over 100 years, politicians everywhere in the world will consistently enact the most efficient, effective laws imaginable to reduce carbon emissions. Dump that far-fetched assumption and the cost could jump by a factor of ten or even 100.
事实上，这个估计还是太过乐观了。因为该计算假设在100年以内，全世界的政治家都能推动通过最高效率且最有效的法律来减少碳排放。倘若去掉了这点假设的话，成本还将上升10倍甚至100倍。