Maybe it is just that I don't understand how Reddit organizes threads, but it looks like a pretty bizarre and illogical mishmash to me. Who are these ATL Icelanders anyway? Where in Europe are they supposed to come from? Why are they able to make Iceland more green and pleasant, how can they be conquering hither and yon all round the Atlantic? How can they survive a WWIII in 2005?
It seems to be just a wish list of fantasy events the authors want to tack in all willy nilly.
Honestly I have only recently found it so can't really comment on how much the timeline makes sense since I haven't read much of it. However, I suspect that if held to the strict standards we hold timelines to here at ah dot com it doesn't make much sense. However, one of my frustrations with the general culture of this site is how it seems to regard well thought out and historically logical timelines as the only legitimate form of our art. I see something like Vekllei which clearly values the utopian aesthetic as much as anything else as perfectly legitamate. And honestly we have a lot of that here in works like Green Antarctica but we seem to get all picky if it is utopian rather than dystopian (I admit the reddit presentation may not be for everyone).
I haven't read to much so I may be being to generous and reacting more to someone attempting something I would like to see more of in Alternate History than the actual objective quality (I have a world of utopias as one of the projects I will probably never attempt but is constantly on my mind and my novel which is in a bit on a stasis attempts to be a depiction of everyday life in an alternate history rather than a accounting of that history as history). But what I have read so for seems OK if taken as a presentation of life in a world rather than strictly realistic historical analysis.
(I believe the stated reason for green Iceland is climate change but he or she engages in some rather nonsensical handwaving to keep the sea levels constant.)