Of course I have an idea. I'm asking if you really think scientists haven't considered this when determining whether global warming is man made.
But anyways, here's the explanation:
https://www.history.com/topics/pre-history/ice-age
scientists have determined that variations in the Earth’s orbit and shifting plate tectonics spur the waxing and waning of these periods.
Basically shifting tectonic plates spur volcanic activity which causes volcanoes to erupt, shooting carbon dioxide into the air. When this happens often enough it heats up the earth, which melts the ice and glaciers and increases the heating. As this dies down (over many thousands of years) the temperature gradually starts to drop, which causes the snow to not fully melt year over year. This traps the snow beneath the top layer and turns it into ice, which eventually form glaciers. These glaciers trap the moisture of the planet which causes a further drop in temperature. As the Glaciers get big enough, they cause massive shifts in the earth's surface, which eventually fuel tectonic activity, and we are back to the beginning of the cycle.
You act like you're asking profound questions that nobody has an answer for, but scientists have had an answer to this one for quite some time. Try and keep up.
Of course I have an idea. I'm asking if you really think scientists haven't considered this when determining whether global warming is man made.