I don't understand a heat pump to be an inherently artificial thing, but I am struggling to think of an example of a naturally occurring heat pump. If there we

I don't understand a heat pump to be an inherently artificial thing, but I am struggling to think of an example of a naturally occurring heat pump. If there were natural valves and compressors (which there might be from certain perspectives) then I could see a naturally occurring heat pump being possible. It seems strange to say process devices are the thing that make a system living or not.