Personally, I watch with the sound off. Hypnotic, they way they move.
Actually, probably not global warming, but man-made environmental damage nonetheless. It's much more likely that they are benefitting from a process called 'eutrophication', which is nutrient enrichment of the water.
Put bluntly, all the artificial fertilizers used in farming in China and Korea have washed into the sea, which causes big blooms of algae, and which the jellyfish seem to love. Everything else seems to hate it though.
Now thats the kind of thing that puts me off swimming in the sea. I mean what the fcuk was that? Can you imagine going for a paddle off your 17 euro blow up alligator in the Atlantic and coming up against one of those feckers.
Atleast the water would prevent people noticing I was crying and I could say that it was the creature screaming and not me.