Yes an interesting read, Gero. (Vox mundi has also posted a link to this Nature article early in this thread).
I do have one gripe.It is an issue that I have seen mentioned on the ASIF several times before - which is how old these papers are by the time they get published.
This paper on Nature Communications was published 4th Jan 2021 and yet has no mention of 2020. The Nares arches were done and dusted by July 2020. 7 months later and no inclusion of the 2020 data. 2017 and 2019 were bad years for arch formation. In 2020 the arch held for approx 200 days, which is more like the longevity arches of old. It is quite likely the arch in 2021 will last over 200 days also.
I have already put a calculation on arch longevity (2007-2020), within the Nares Strait, in post 2448 of this thread. Because of bad years 2017 and 2019 the 5 year average has dropped considerably but 2020 and 2021 will make it rise again (a little).
Like for so much of the Arctic, time is running out for the arches in the Nares. I was surprised that for both 2020 and now 2021, arch formation has begun relatively early. Whilst the Nature Comms article is a good read. It is not up to date.