Answer:
it is said that the Ice Ages began 2.4 million years ago and ended approximately 11,500 years ago.
Step-by-step explanation:
During this time Carbon-Dioxide (a poisonous and warming gas) levels rose dramatically by about 180 ppm to 280 ppm.
This caused the major retreat of glaciers that ran across continents...
There were other gases but they were in VERY small amounts...
(APART FROM OXYGEN)