"That is three to four times the global average, and it means the coast could see 20–29 centimetres of sea-level rise on top of the metre predicted for the world as a whole by 2100." ~ Sci. AM. article just linked to

Words such as "could" and "predicted" are ot usually part of science.

They are best saved for sorcery, augury nor agenda-driven politics.

The oceans of the world have been rising about 2 mm per decade for the last 100 years or so, but various tides in certain ocean push the water up or down and make the change look larger or smaller than it actually is. Tides change like everything else. The real rise in ocean level wotldwide is exactly the same since all the oceans are joined as a single body of water.