Actually, the gradual rise in sea level exactly matches the rise in
the number of boats on the sea! (If you don't believe that just ask me!)
Therefore, all you sailors are direct contributors and should be ashamed!
Gordon

Rubbish!

It is directly due to the pollution of the oceans by modern industrial
waste and agricultural chemofertilsers which have drastically reduced
the sponge population.

Phylum Porifera are very sensitive to pollutants.