I don't think our current system is nearly as robust as you think. Trump's first term laid that bare.
So many laws dictating what the president can and can't do don't have any actual repercussions for breaking them written in them because it was assumed impeachment would be sufficient. Trump showed that with our current system that means if you can't guarantee you'll have 67 votes in the Senate, then those laws may as well not exist. And every week the Supreme Court shows how much "settled case law" isn't anymore, so with a corrupt high court in his league, even the laws that do have teeth may be subverted.
We absolutely need to make changes to shore up the system and plug the gaps, but we have to do so with care that we don't end up handing new, more powerful weapons to the very bad actors we're trying to protect against.
And this horrible story of uprooting not only your life but your entire community and its history to flee the rising tide is going to be one of the better stories. These islands are "lucky" to be part of a nation that is based on a continent and has room it can move these people to.
There are many entirely island countries that will have to evacuate to other countries. Maybe some other countries will offer some of them somewhere to go, but I guarantee it won't be enough. And it's going to accelerate. And it's going to be happening at the same time some continental nations in the equatorial region will be evacuating north due to extreme heat or other extreme weather.
Scientists have been warning this was coming for as long as they've been warning about climate change. And it's here. It's starting now.