The stabilisation of the long-term Cretaceous greenhouse climate: Contribution from the semi-periodical burial of phosphorus in the ocean

The mechanism responsible for the regulation of long-term climate stability is still an enigma in principle. The geochemical CO2 cycle in the Earthʹs surface system is thought to be a fundamental mechanism in the regulation of Earthʹs climate. However, this idea has often been criticised for many reasons. Here, we conducted a spectrum analysis on the global marine phosphorus burial records of the Cretaceous ocean with the aim of determining the role of the phosphorus cycle in the regulation of the greenhouse climate. The results show that there are four periodicities of 38, 19, 5.5 and 12.1 myr existing in the record, with the first three bands indicating the contribution of the semi-periodical burial of phosphorus in the ocean to the stabilisation of long-term Cretaceous greenhouse climate implemented by the coupling of carbon and phosphorus cycle. With stronger tectonic activity, more CO2 was emitted to the atmosphere, leading to a warmer climate. However, the chemical weathering was accelerated and at the same time, the input of phosphorus to the ocean increased the burial of organic carbon, resulting in a higher consumption of CO2. It is interesting to note that this is the first time that the palaeoclimatic significance of the 38 myr band for the marine phosphorus burial record during the Cretaceous, and potentially for the greenhouse period of 34 myr to the start of the Cretaceous, has been clearly identified. Further work is still needed to explore the significance of the band of 12.1 myr.