The hydrological cycle in the past 540 million years

Earth has undergone dramatic temperature fluctuations and the tectonic process of continental breaking up and reassembling in the past 540 million years. How these caused changes in the global hydrological cycle is an interesting question. To study the evolution of the global hydrological cycle since the Cambrian, we carried out 55 equilibrium simulations to simulate climate evolution in the past 540 million years, using CESM1.2.2. It is found that the global mean precipitation is closely correlated with the global mean surface temperature (GMST), especially oceanic precipitation has high correlation with GMST, with a coefficient of 0.92. Land precipitation also has statistically significant correlation with GMST. However, the correlation coefficient is much lower. Further analysis shows that land precipitation is also determined by continental fragmentation, mean latitudes, and total area, and that the semi-arid area is most sensitive to GMST changes.