A shame about that Maunder Minimum
Once the measurements improved dramatically the evidence from ice cores revealed that a new Ice Age usually comes on in less than twenty years, sometimes as quickly as three days.
The evidence shows this climate shift can be traced ultimately to a fluctuation in the background cosmic radiation. This background "field" changes the absorption and release of heat by plasma in the Sun at the same time it alters cloud cover on Earth, blocking incoming sunlight from reaching the planet's surface. It also alters the magnetic field called the Heliosphere that the Earth shares with the Sun leading to dramatic changes in the molten core of the planet and in tectonic forces worldwide, most importantly on the ocean floor where it begins to heat the deepest water.
If that sounds like an awful lot of change at once, you're right. It becomes obvious why climate shifts to new Ice Ages are so sudden.
Seeing these relationships in the natural order is a kind of evolutionary survival test. Homo Sapiens has failed that test utterly. Seven billion people worrying about global warming the last twenty years is the worst kind of biological washout. It is a kind of expulsion from survival university and you cannot enroll again after a grace period.
You will start to see why the Neanderthals were born winners for a million years. Homo Sapiens makes fun of them because they are so often found in deep caves with stores of food and access to fresh water. Saps is like a grasshopper puzzled at the behaviour of ants. The Neanderthal could be regarded as class valedictorian of survival university. They were naturals. They beat every single thing this planet could throw at them for one million years and came through with flying colors. Wonder why I think somebody deliberately threw Homo Sapiens at them? What are the odds of blind nature coming up with the one unique kind of animal that could have defeated them and dumping them suddenly at the southern tip of Europe? Homo Sapiens appears first at the starting line into Neanderthal territory. Saps has no pedigree. There is no evidence he existed anywhere else. He just dropped in out of the clear blue sky right at the start of the Holocene in exactly the right place to exterminate 'Thals. What are the odds? A just-so story.
The tragedy is that the Neanderthals were the good ones. Everything about them was about as nice as people would be willing to believe. They were as gentle and kind as they were honest, loyal and brave. Homo Sapiens is almost like their evil doppleganger, the opposite of them in every way ... including being prudent, wise and farsighted. That is why the human race is not prepared for the coming Ice Age.