nature limits carbon dioxide
Early life on Earth The early cretaceous saw carbon dioxide levels at 1000 parts per million. Then the precursor to photosynthesis evolved in carbon dioxide fell to just one part per million. Which are due to the deaths of 90% of biological life on earth. A bigger mass extinction than the death the dinosaurs. Then the existing animals multiplied in numbers. Breathing in the oxygen excreted by plants. An e.g. in the carbohydrates there were a plant biomass. In the Jurassic carbon dioxide levels in the warm periods were at four PPM. Twice the present terrestrial limit. But there were three natural ice ages. One lasting a record 1000 years. The carbon dioxide rising to eight PPM: as photosynthesis on land or in the seas covered by sea ice shut down. Plus four to the modern age. The modern temperate carbon dioxide level in the afternoon air, is omitted to just two parts per million. As plant's greedily gobble up all the c...