Not sure where you get your information. Mine came from geology classes The earth has experience 5 major ice ages that occured during a period of 4.5 billion or so years. The most recent one is know as Quaternary glaciation beginning around 2.58 million years ago continuing to today whiich encompasesnumerous shorter glacial and interglacial periods which also impact ther earths climate sea levales and biodiversity.
the term ice age refers to a period in which the earth experiences colder temperatures and expansion of ice around the globe when they end the earth experiences warmer temperatures again. A process we have been in for centuries. Occasionaly there will be a more local ice age such as the last little ice age wich was from around 1450 to 1850 occuring off and on in the North Atlantic the end of ice ages was influenced by several factors.
Milankovitch Cycles variation of the earths orbit and axial tilt which significantlyly affect climate patterns. They alter the distrinbution of sunlight causing the earth to warm and ice to melt. No human activity involved.
Atmospheric CHanges Increase levels of greenhouse gases such as carbon diioxide and methaane which are released from the trapped gases in the ice sheets which enhances the greenhouse effect and accelerating the warming process. It is the gas that was stored thousaands of yeras ago, not current carbon dioxide
Ocean Currents changes in ocean currents also play a rolee in climate shift. The redistribution of warm ocean warter leads to increased in temperature in polar regions, promoting ice melt.
Feedback Mechanisms . As ice melts , it reduceste Earths albedo (reflectivity) , causing more solar energy to be absorbed and further increasing temperatures. This positive feedback loop leads to rapid climate changees.