I scanned the related research link page, curious if any artifacts have been uncovered indicating exposure in the distant past but the content seems to not cover that question or I missed it.
According to Wiki[1] and UC San Diego's website[2], this was actually a 650 ft tsunami. The location probably helped for the wave's height. Per the same article, it's far from the biggest ever theorized but in a good position in the biggest ever recorded.
The mineral and gas resources are one thing, but it's a pittance compared to the real reason America wants it.
With a melted Arctic sea route, control over the Arctic becomes incredibly strategic. It becomes most optimal shipping route in the world and quickly connects Europe, Asia, and North America. You really want to have your navy there.
China covets Taiwan because of naval strategy more than any other reason. This is the same reason America wants Greenland. It isn't Trump that wants it so bad, it's the DoD.
Look at China's posture on and dealings with Greenland. They really want to be there, and for good reason.
It's no question that some countries benefit immensely from global warming. Russia's gains in particular are incredible: unblocking of their naval fleet, easy transportation (water is vastly superior to land), reconnection of eastern and western Russia, easy access to massive amounts of new resources, increase in stable and dwellable land. It's insane how much they stand to gain.
That is only a small part though. Russia has a lot more access, as does Canada. However between Greenland and Alaska the US would control shipping by controlling the choke points everyone needs to go through. (Canada and Russia would also have plenty of control).
Though it makes more sense to be friends with whoever controls Greenland.
The US already controls the most important Arctic chokepoint. What's the point of a Northwest passage that doesn't go through the Bering strait? The only other Arctic chokepoint of any mercantile significance (the Labrador sea) is already patrolled by the US coast guard as part of ice patrols with Canada, in addition to US bases in the high Arctic and any US planes in Iceland.
I'm not comfortable with empires. I don't want the US to control Guam (I'm not sure about just having a navy base), Hawaii, or other Pacific islands. I don't want France to have a land border with Brazil, and I don't want Denmark to control Greenland. I don't want the US to control Greenland though (they can either be independent or join Canada).