alt Hacker NewsMost people do not know that we are in an icehouse phase, which is rare.
Earth spends most of its time in greenhouse phases.
"A "greenhouse Earth" is a period during which no continental glaciers exist anywhere on the planet... Earth has been in a greenhouse state for about 85% of its history.
"Earth is now in an icehouse state, and ice sheets are present in both poles simultaneously... Earth's current icehouse state is known as the Quaternary Ice Age and began approximately 2.58 million years ago... Earth is expected to continue to transition between glacial and interglacial periods until the cessation of the Quaternary Ice Age and will then enter another greenhouse state."
We'll be much closer to a greenhouse earth than a glacial earth if we get that 4°C warming, so the distinction is more academic than practical in most contexts. What's a century here or there in geologic time?