Thinking further, I would go with importance among those options for ‘total influence of an era’ but none of those terms capture the ‘per capita/resource’ element, and so all would tend to be misleading in that way. I think you would need an explicit additional qualifier to mean not ‘this is the century when things will be decided’ but ‘this is the century when marginal influence is highest, largely because ~no one tried or will try.’
Thinking further, I would go with importance among those options for ‘total influence of an era’ but none of those terms capture the ‘per capita/resource’ element, and so all would tend to be misleading in that way. I think you would need an explicit additional qualifier to mean not ‘this is the century when things will be decided’ but ‘this is the century when marginal influence is highest, largely because ~no one tried or will try.’