[mc5cents]

Better knowledge of past "greenhouse" conditions will enhance guesses about the effects of increasing CO2 today.

The early Eocene - often referred to as the Eocene greenhouse - has been a subject of increasing interest in recent years as a "warm analogue" of the current Earth.

So, CO2 was the culprit 53 million years ago too. Wow. Who knew? I can't wait until they dig up those old SUVs and coal fired power plants.

[muawiyah]

The asteroid/comet/meteorite strike that wiped out the dinosaurs 65 million years ago pretty much killed off all the major plant eaters ~ so by 53 million years ago the plants were having their way with the Earth, breeding at will, all over the place, out doors, in plain sight ~ no doubt there were massive CO2 releasing fires everywhere.

It took several more million years to recover the balance.

[OldNavyVet]

Adding to that, page 231 of "Darwin's Ghost" tells us ...

Five hundred million years ago the air had twenty times as much carbon dioxide as it contains now. This led to a natural "greenhouse" effect which was reversed two hundred million years later when the level of the gas dropped. Oxygen, too, has swung between extremes. Twice as much of the gas as today allowed the growth of enormous plants, of spiders the size of a book, and of scorpions a foot long. A later burst led to the development of aerial reptiles such as Quet-zalcoatlus, with wings forty feet across.