Well, if the envirowackos are successful in convincing the world of the fundamental immorality of industrialization then by the 29th century we’ll be all living with medieval technology. In which case there will be nothing to be done about it - whatever happens, happens.
What's funny is, the wackos don't realize that the oil and gas economy is better for the environment than the old horse-drawn economy.
Oil and gas have a much smaller footprint than all the acres we used to need to grow the food for the horses. So much so, that with a lot less farmland under cultivation, the forests of North America have come back to cover as much area now as in the 1700s.
So much forest in fact, that North America has become a carbon SINK -- after crossing the continent, there's less CO2 in the eastern seaboard air than the western seaboard. (The prevailing wind is west to east.)
So not only is the US not adding to atmospheric CO2, we're taking the Chinese CO2 out of the air.