Their islands may be sinking. No one has been able to quantify any sea level rise, beyond that which is normal for a world coming out of the last ice age, to my satisfaction.
Any point of reference on the earth is subject to the quandary: sea rising, or land falling. The best satellite measurement I have found was this: in the past 15 years, the sea has risen 4mm, plus or minus 7mm. Sorry, but those are the only numbers I have been able to find; and I need numbers to do this conversation — not anecdotes about folks on the most marginal land on earth whose islands may be sinking.
Sorry, all out of valid data, so we'll rely on emotional stories instead.