Signs seem to indicate that the ability to keep our heads in the sand when it comes to our environmental impact may soon disappear. Brooke Jarvis shares how things are already changing from one generation to another in some island cultures. > I decided to walk the islands perimeter, but found it difficult: Large sections of the trail around the island were missing, the land fallen into the waves. For those who had been on these islands for more than 50 years: > Thomas, who was born here in 195…