What is the science behind beliefs and disbeliefs in "climate change?"

The climate changes naturally. Until the AGW nonsense every all the climatologists agreed that the Medieval Warm Period was a global event the crashed into the Little Ice age an climate event that caused the death of millions from crop failures and disease not to mention the unpopular people that were burned as witches after a storm like hadn't happened in living memory swept across Europe. At about the peak of this cold event a scientific instrument was invented which revolutionized weather recording; the thermometer. So the recording of temperature as a number started when the earth was about as cold as it had been since the rise of civilization. this did not stop there being panicked claims of a coming Ice age during the global cooling from the early 1940s through the late 1970s. The confusion arises when we begin talking about the CAUSE of climate change (which is also fairly obvious, although harder to demonstrate, when one looks at the physics behind it). You have a slightly better chance of finding a scientist who disputes whether or not it is a human-made consequence.