3 million years ago, greenhouse gas was lower (at 360ppm). Temperatures were warmer, and sea levels were 20 meters higher.
Professor Gavin Foster: “The reason we don’t see #Pliocene-like temperatures and sea-levels yet today is because it takes a while for Earth’s @climate to fully equilibrate (catch up) to higher CO2 levels and, because of human emissions, CO2 levels are still climbing.”
Julia Steinberger: https://www.resilience.org/stories/2020-07-15/cogs-in-the-climate-machine/


