"I never again thought of environmentalism as a movement about the politics of land without noticing how often there were about it inklings of the divine."Environmentalists are sometimes characterized as possessing a religious zeal. In this light, Brad Pitt's plantings and World Jump Day might be called environmental sacraments.
-Jack Hitt, "A Gospel According to the Earth"
However you want to think of World Jump Day, it seems that 600 million jumpers are likely to cause, at best, a very minor tectonic shift. I don't think that such an effort will save the planet, but it is an interesting idea.