CO2 is such a joke. Call me when there's actually something toxic filling the air instead of the air that my food's food breaths.

As for island vs boat, if you can get fresh water on a boat (you can, desalination) you can do so on an island as well.

A boat or seastead will be better against a tsunami but in the past 100 years outside of a few outliers most tsunamis did not reach more than 30 meters above sea level, though just a few meters high can kill a lot of people as the ocean is very powerful and the water just keeps coming. The one in Indonesia killed more due to the inability for taking care of people after the event as opposed to the tsunami itself.

I would say though that a boat will likely be necessary in the near future if you wish to get to other countries. Though if you have "fuck you money" and you buy an island, you'll likely also be buying a boat to get to your island.

It is certainly something I have considered. There are several islands for sale in Panama. Though we are also considering movable versions of our floating homes so that could be a viable solution some day. A floating home that can sit in 5 meter waves allows you to live in a whole lot of places.