56 million years ago, the Earth suddenly heated up – and many plants stopped working properly
https://theconversation.com/56-million-years-ago-the-earth-suddenly-heated-up-and-many-plants-stopped-working-properly-270291A World Without Clouds
https://www.quantamagazine.org/cloud-loss-could-add-8-degrees-to-global-warming-20190225/Paleocene–Eocene Thermal Maximum - Wikipedia
https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_MaximumThe Last Time the Globe Warmed - YouTube
https://www.youtube.com/watch?v=ldLBoErAhz4