Global Warming accelerant?

I was just thinking how a country (or some small group of people) can kill over a billion people instantaneously. Since global warming is such a concern considering how it can raise the global sea level and cause mass flooding, wouldn't it be easy for a rogue nation (like Iran or North Korea), to drop a nuke onto Anarctica, and thus greatly accelerate the melting process with the thermonuclear heat that follows? I guess you don't even need a nuclear bomb, but just any large enough bomb that releases substantial heat.