Responding to both this post and the other one. The thing is, I don't discount that they were masters of their environment and highly adapted to it within the limits of their technology. My point is that this is an incredibly, unbelievably hostile environment. I've had friends who have worked up on the ice with Inuit. I've visited the high arctic myself and organized high latitude expeditions somewhat farther south. The frostbite from those experiences was more than sufficient to give me a deep respect for the environment.

That's today, with modern equipment and a relatively tame polar climate. The coastal North Pacific during the LGM was an entirely different beast. We don't have a lot of direct evidence from Beringian populations during the LGM. What little evidence we have from their immediate ancestors in Siberia is that the onset of the LGM caused severe regional depopulations, with most survivors seemingly fleeing to refugia like PHSK, inland Beringia, and the south. There's still an open debate whether this depopulation was total (as in no human habitation of the region) or merely near-total, with most scholars leaning towards the latter these days. Humans definitely struggled.

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But assuming you're a Beringian survivalist who wants to run down to Oregon for some salmon, how would you do it (assuming a reasonably modern understanding based on Inuit adaptations)?

First, you actually want sea ice, not to travel along the land-bound glaciers during summer. Land-ice is dangerous, full of crevasses, and usually far from flat. The fjords and sounds of the modern high arctic are semi-inaccessible near large glaciers even to modern Inuit due to the dangers of summer icebergs. They usually wait until winter or spring to hunt and fish in these areas. However, it's the LGM and you probably don't have the incredible cold-weather technology of modern Inuit (better than most commercial jackets we can buy). Whatever boat you're using also isn't going to survive the oceanic storms either. Most modern boats can't. Both of these mean winter's out, even though it's the best travel season today.

However, there's a brief period between the end of winter and the beginning of summer other places like to call Spring. The ice is increasingly dangerous as the season progresses, but it's traversable and you can shelter in the unglaciated coves during the summer as you head south. You repeat this for years and maybe you can get enough people south of the ice to survive before the ice age rears its head again and collapses the fragile marine ecosystems you rely on by starving them of sunlight with permanent sea ice.

It's possible, but unbelievably tough. Why would you leave the relatively temperate Beringian climate for this kind of hell? The paper's implicit answer is that things might have been just good enough for a short while that this was plausible, even with all the ecosystem recovery that had to happen to make it a viable route.

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Alternatively, you go way the hell out past the Aleutians into the middle of the Pacific to try and catch a current back south. If you hit a storm, you will almost certainly die. This is technically possible, but it stretches the bounds of credulity to believe a viable population got south of the ice this way.

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The paper doesn't really get into these kinds of specifics because, well, climate paper. It's very hard to get high resolution climate results, so I'm impressed that the data is even this good (as an archaeologist).