Theoretical super-weapon?

Question

I'm looking for a fictional weapon based on either theoretical or hypothetical science in the real world. The weapon is for a story I'm writing and has to raise a large body of ocean water (I believe one website said 30 square miles, but I need enough to take down the ozone layer so 200-300 square miles) to an excess of 120 degree Fahrenheit (thus creating conditions capable of producing a hypercane)

Answer 1

For kicks, you might try calculating how much energy it takes to heat 200 square miles to some significant depth (it's pretty easy to calculate).  When I did this I estimated that it would require a weapon several thousand times larger than the largest bomb ever created.  To accomplish this, you'd better use a matter/antimatter bomb.

Answer 2

some kind of plasma gun...