In Portugal's case, the interior would have been ok, apart from the cooling of the weather post-fall, that would make it temporarily more northern-European in temperatures, but that could be semi-remedied, by adapting to the temporarily changed weather and moving to the coast to rebuild things...
Nice concept. :)
A small nitpick, Extremadura is too large a geographical area to be a simple Dukedom in Portuguese tradition. I suggest something more like Prince/Princess of Estremadura (Príncipe/Princesa da Estremadura).
Are there investigations by TTL British Government to find the sources?
If this is found, internationally it would be a casus belli.
And there would probably occur a lot of arrests and confiscations in Ireland.
The world is getting ready for new wars, while the anthropocene extinction made it to became a mix of 1980's post apocalyptic fiction and the movie AI.
Good to see TTL Portugal become free again.
Sorry to hear that. :( Hope you reconsider, but wish you good luck in your projects.
Happy new year...