Where does “subarctic” come from?

I need to work through this chain carefully, but I notice there's a significant problem with the given chain. Let me trace what's provided: English Arctic | Latin sub | Proto-Italic supo | Proto-Indo-European upo | Ancient Greek -ικός | Proto-Indo-European h₂ŕ̥tḱos | Proto-Indo-European -kos The chain seems to conflate multiple etymological paths and contains inconsistencies. However, working with what's given and the headword "subarctic": - "subarctic" is English - "sub" is Latin (meaning "under") - "Arctic" comes from Ancient Greek ἀρκτικός (arktikós, relating to the bear/north) - Which derives from Proto-Indo-European h₂ŕ̥tḱos (bear) But the chain as

subarctic (English): Region immediately outside of the Arctic Circle...

Definitions

  1. Region immediately outside of the Arctic Circle...

Ancestry of “subarctic”, step by step

subarctic traces back through two separate lines of ancestry.

via Romanian arctic

StepLanguageWordMeaning
1RomanianarcticArctic
2FrencharctiqueArctic
3Old Frencharctique
4Latinarcticusnorthern, arctic
5Ancient Greekἀρκτικόςhaving to do with the Great Bear; northern lands;...
6Ancient Greek-ικόςof or pertaining to, in the manner of; -ic
7Ancient Greek-κόςforms adjectives with the sense of 'of or...
8Proto-Indo-European-ḱos-y, -ic

via English Arctic

StepLanguageWordMeaning
1EnglishArcticPertaining to the celestial north pole, or to the...
2Middle Frenchartique
Every word from Proto-Indo-European -ḱos