Yeah. The last time CO2 levels were as low as they are now was probably during the carboniferous about 350+ million years ago. Its when trees and vascular plants first really came to dominate land. It seems from the evidence that there was a weird kind of arms race among green leafy things on developing new means to photosynthesise more effectively. Large parts of the planet were dominated by low lying tropical swamps. We can see the evidence of this in all our coal fields most of which date to this time. This explosion of plant life extracted most of the CO2 out of the atmosphere causing a cooling trend and sea levels to drop.
Earth returned to the Norm after the Permian mass extinction to a more hot house climate due to some kind of catastrophic volcanic event. In England our Triassic rocks are dominated by sand stone. Large parts of the land being covered by arid desert. Its only since the extinction of the dinosaurs that the trend seems to have reversed. Likely a combination of factors - the break up of the old super continents, distribution of most of the land mass and vegetation to the Northern hemisphere but in such a way where a lot of it has enough rainfall to grow in summer. The big one was probably the Indian subcontinent slamming into Eurasia and pushing up the Himalayas and increasing weathering rates. Most recently changes to ocean circulation due to the isthmus of Panama forming and the fact that the organisms that oxygenate the ocean today have learned a lot of new tricks and are more efficient meaning the oceans are a bigger carbon sink now than in the past.
The current emissions and warming trends are a drop in the ocean really. About 55 million years ago there was a curious event called the PETM where CO2 levels spiked to something like 1500ppm almost overnight in geologic terms. There are fossils of alligators in the arctic ocean from that time. It was over almost as quickly as it started. Likely it created some kind of catastrophic greening effect in the Northern hemisphere which counteracted the warming.
Yeah. The last time CO2 levels were as low as they are now was probably during the carboniferous about 350+ million years ago. Its when trees and vascular plants first really came to dominate land. It seems from the evidence that there was a weird kind of arms race among green leafy things on developing new means to photosynthesise more effectively. Large parts of the planet were dominated by low lying tropical swamps. We can see the evidence of this in all our coal fields most of which date to this time. This explosion of plant life extracted most of the CO2 out of the atmosphere causing a cooling trend and sea levels to drop.
Earth returned to the Norm after the Permian mass extinction to a more hot house climate due to some kind of catastrophic volcanic event. In England our Triassic rocks are dominated by sand stone. Large parts of the land being covered by arid desert. Its only since the extinction of the dinosaurs that the trend seems to have reversed. Likely a combination of factors - the break up of the old super continents, distribution of most of the land mass and vegetation to the Northern hemisphere but in such a way where a lot of it has enough rainfall to grow in summer. The big one was probably the Indian subcontinent slamming into Eurasia and pushing up the Himalayas and increasing weathering rates. Most recently changes to ocean circulation due to the isthmus of Panama forming and the fact that the organisms that oxygenate the ocean today have learned a lot of new tricks and are more efficient meaning the oceans are a bigger carbon sink now than in the past.
The current emissions and warming trends are a drop in the ocean really. About 55 million years ago there was a curious event called the PETM where CO2 levels spiked to something like 1500ppm almost overnight in geologic terms. There are fossils of alligators in the arctic ocean from that time. It was over almost as quickly as it started. Likely it created some kind of catastrophic greening effect in the Northern hemisphere which counteracted the warming.