100ft!!! I'd say about 4 ft TBH. Actually rising sea -level is a bit of red herring - they're coral atolls and the "land" is just where a storm pushes up the dead coral above normal sea level - as the reefs grow upwards under water the islands are replenished by storms - the fact the whole place disapears under water when it happens is ..... unfortunate... but not new........
As I said the airfield pictured is a long way from either.........................