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Remember, average global warming over land is double the global average because of the cooling influence of our oceans and ice sheets, or 3.56 degrees C in December (6.4 F). and the average over the arctic is four times the global average or 7.12 C (12.8 F). Importantly, the increase in extreme temperature is far greater than the average, and extreme weather increases nonlinearly because of the basics of heat and energy physics, where a little warming does not create a little more extremeness in the weather, it creates a lot more.