Aberrants can try. But without long term maintenance, something like Zushima just feels like a magic 'get out of extinction' card. Like Firanai mentioned above, Novas may be able to fix the climate for a while - but they won't be addressing the core problem - that's a job for a united humanity in Aeon/Trinity. At which point, at least some of it will be irreversible.
Disaster brings us together - but at some point this has to become a human responsibility and it seems to me that Aeon/Trinity has the right shoulders to bear it.
I think new maritime environments, industrial re-freezing efforts, sunken coastal cities and their new mezzanine levels would be an interesting spice to bring the setting more up to date without sacrificing much of the original premise and atmousphere. Sci fi has been doing interesting things with climate change for decades, why not Aeon/Trinity?
What would we lose?