A Simple Model for the Hydrological Change Over Phanerozoic: Untangling Contributions From Climate and Continental Evolution

Earth's hydrological cycle has undergone significant change during geological periods. While it is known that the global-mean surface temperature (GMST) is the first-order controlling factor, there are other factors less studied. We performed paleoclimate simulations to examine the evolution of global-mean precipitation (GMP) from 540 million years ago to today. The GMP primarily varies with GMST, however, change in the low-latitude land fraction is also important. An increase in land fraction can directly reduce GMP by reducing latent heat and increasing sensible heat. Furthermore, the weakened greenhouse gas effect of the drier atmosphere further amplify the direct impact by approximately 44%. A simple model of GMP as a function of GMST and land area fraction is developed, which effectively reproduces the simulation results throughout the Phanerozoic Eon. Our results clearly separate the effects of climate change and continental evolution on hydrological change over geological time and elucidate the functional mechanism.