Because China will claim that it's their hereditary rightful property.
I'm def gonna caveat this right up front by saying it's a reasonable, non-racist joke based on recent behaviors and conflicts, just as much as it's sadly funny to make similar jokes about the US invading countries full of brown people and oil. Sometimes things are bitterly funny because they're true.
Or read a history book and learn about the truly horrific things humanity has done over the past 3000+ years to put current events in perspective. Or read something about the universe and realize how incredibly insignificant and meaningless the entirety of humanity is. Or get drunk
It's dangerous to anyone directly by it as it happens and in the form of pumice rafts if any where created, but that's about it.
Depending upon the composition and how much material gets built up, it will likely erode away fairly quickly and may pose a hazard when not visible but still just under the waves or something.
I don't think Valcanos are effected by climate change. They do release a fair amount of CO2 and can effect climate change, but I don't think the other direction has any effect. Maybe fracking or something can cause it, but this kind of thing is expected to happen frequently in this area. It's nothing to be concerned about.
The CO2 isn't the problem, it's the sulfur gases. They basically do the opposite of CO2. When Krakatoa errupted, it lowered global temperatures by 0.5 C. It canceled summer and caused famines. When large volcanoes erupt they don't cause a climate catastrophe, they ARE the climate.
Anyway, here's a neat video so you're not just believing a stranger on the internet.