When a young boy concludes rising sea levels will sink his dream island Tasmania, he must engage all strength to swim and fly to his paradise before time runs out.

If it's a comedy, I think you need to give us more of a sense of that in the logline.

if it's a drama.... wouldn't the inhabitants of Tasmania be fleeing for their lives?

Is this the general consensus... The rising sea levels about to sink Tasmania is acceptable as the boy's fear, used to increase the stakes, but is not his main motivation for wanting to get there.

So the rising sea levels about to sink Tasmania seem acceptable to everyone providing it is only used to increase the stakes, & is not the main motivation?