Final answer:
The Phanerozoic has experienced several icehouse events, characterized by periods of cooling and the growth of glaciers on land.
Step-by-step explanation:
The Phanerozoic, which is the current geological eon, has experienced several icehouse events. These events are characterized by periods of cooling on the planet and the growth of glaciers on land. While it is difficult to determine the exact number of icehouse events, scientists have identified at least five significant periods of cooling.