TOO MANY JELLY FISH?

I've been reading that there is a JELLY FISH AROUND THE WORLD AND THAT IT'S GLOBAL!  While scientists seem to be not worried, I can't help but wonder how or if this ties in with all the changes in the earth's temperature that is melting ice packs and changing the weather.  Be the changes part of a natural cycle, the earth responding to human use of resources, or something more mysterious, I hope to learn more soon!