Coral islands sink. The weight of the reef causes the sea floor to subside. Sometimes it subsides faster than the coral grows, like when there is a big cyclone blows through and erodes the reef.
It's all a part of the circle of life. Extinction happens. It's a natural phenomenon. Besides, it was a rat.
Right, geologically speaking atolls have a limited life expectancy. Why let the truth get in the way of our climate change objectives