How to Change Biome

So i'm making a global warming mod, and want to have the ice melt in snowy biomes. However, having the world manually remove ice is an enormous task and if it happens in a frozen ocean the game crashes. So, as a solution to that, I would like to change the entire world to a custom wasteland biome. This biome would have a grey sky and be very hot so the ice melts, and other global warming features would be easier to make. however, I cannot figure out how to change a biome (sort of like world edit) in the world. Is this possible