[ProtectOurFreedom]

Earth is still in an ice age that began about 3.2 million years ago. Earth's poles have been covered with ice throughout the age, and thick ice sheets periodically grow and recede from poles in cycles that have occurred more than 100 times.

Wow, that is truly astonishing. I thought there were a couple Ice Ages with the Pleistocene being the last one and ending about 10,000 years ago. That's the first I've heard that we've been through 100 cycles of ice sheet advance/retreat and we are still in an ice age that began 3.2 million years ago.

How in the world can they determine we've been through more than 100 cycles? Wouldn't each glaciation period wipe out evidence of all former glaciations? When you see glacial striations on bedrock and the vast terminal moraines in upstate NY, you get a real sense for the power of glaciers to wipe everything out.

[Moonman62]

https://www.ncdc.noaa.gov/abrupt-climate-change/Glacial-Interglacial%20Cycles

[marktwain]

Wouldn't each glaciation period wipe out evidence of all former glaciations?

No. There are other indications in sediment in the ocean and fossil record.

The oceans rise and fall through an ice age cycle.

There is quite a bit of evidence of multiple ice ages.

It has been a mystery what caused them to start.

This theory takes a stab at it.

All of human existence is in the ice age and interglacials.

[outofsalt]

This is a good overview, https://geology.utah.gov/map-pub/survey-notes/glad-you-asked/ice-ages-what-are-they-and-what-causes-them/