Does that mean letting the ground do the breaking for free?

Thanks for breaking it down so well!

>it has the highest specific reactivity at lower temperatures

Does that mean that deuterium-tritium reactions need less energy for the reaction to start? Is that because tritium is less stable than the other isotopes?

That's a great response. One thing to add: sea levels rise and fall over relatively short timescales, geologically speaking, which can greatly affect coastal map shape.

For example, 40,000 years ago, during the last ice age, sea levels were lower. Thus, there was solid land between Siberia and Alaska (Beringia land mass), and the British Isles and the Netherlands. Our current coastal regions were inland regions, and what is now submerged land was once the coast. In some areas, such as southern Africa, this could mean that the coast was several hundred kilometers further out than it is today. Islands such as New Zealand would have been bigger and possibly connected, too.

On the other hand, if sea levels keep rising, we may have to remove parts of Florida, New York, California and many island nations from maps over the coming decades and centuries.