“...risen only 4 inches in the past century....”
Are they really certain the sea has risen? I live near the ocean and it appears to me that people see the beach disappear and say the sea is rising when it is actually beach erosion from wind and waves. The prevailing winds are out of the NE so the sand goes out to sea and forms a reef or goes to beaches south where the erosion happens as well.
The sea is rising and land is either subsiding or rising everywhere. Sea level rise had been almost completely constant since 1860. It is not accelerating and it is almost completely unrelated to human activity.