I taught an introductory course in Geology at the University of the South Pacific in 1977. Each of the countries that participated in USP was invited to send 2 students. They had varying interests, and it was amusing to watch how they woke up when we were teaching geology relating to their own job. Some were interested in gold mining, others in highways and landslides, some in coastal erosion, and others in active volcanoes. It was rather a surprise when the sole student from Tuvalu approached me one day and said "Sir, this is all wasted on me. My island is just made of sand." Any news from Tuvalu always struck a chord from that moment.
Since then, of course, Tuvalu has become "hot news" as the favourite island to be doomed by sea level rise driven by global warming, allegedly caused in turn by anthropogenic carbon dioxide. If you look up Tuvalu on the internet you are inundated with articles about its impending fate. Tuvalu has become the touchstone for alarm about global warming and rising sea level.
The geological background There may have been good reason to think that Tuvalu was doomed anyway. Charles Darwin, who was a geologist before he became a biologist, gave us the Darwin theory of coral islands which has been largely substantiated since his time. The idea is this: When a new volcano erupts above sea level in the tropical ocean, corals eventually colonise the shore. They can grow upwards and outwards (away from the volcanic island) but they can’t grow above sea level. The coral first forms a fringing reef, in contact with the island. As it grows outwards a lagoon forms between the island and the living reef, which is then a barrier reef. If the original volcano sinks beneath the waves a ring of coral betrays its location as an atoll.