230 / 2024-09-12 09:23:50

Maintenance of the Great Late Ediacaran Ice Age

Ediacaran,ice age,weathering,CESM,true polar wander

Session 42 - Deep-time ocean and climate changes: insights from models and proxies

The extensive glaciations in late Ediacaran, lasting from ~580 to 560Ma or younger, may have played a critical role in the appearance of early animals and the Cambrian explosion aftermath. However, the explanation of maintenance for this diachronous and continuous glacial epoch is still unclear. Here, using the Earth system model (CESM 1.2.2) and revised weathering model, we demonstrate that the newly exposed regions with high weatherability from glaciated continents to ice-free tropics, controlled by a wholesale rotation of solid Earth via true polar wander (TPW), could increase the weathering rate to maintain uninterrupted Ediacaran glaciation, especially during 575-565 Ma. Based on model simulations and observations, the atmospheric CO₂ level would be <280 ppmv in 575-565 Ma and <140 ppmv in 580 Ma and 560 Ma, but all higher than 35 ppmv to avoid snowball Earth. The CO₂ fluctuation during late Ediacaran glaciation could be confined within twice of that in 580 Ma due to the effects of TPW. Concomitantly, the increased weathering rate near newly exposed areas could have increased nutrient supply to the oceans and eventually supported marine life evolution during the Ediacaran. Therefore, TPW might trigger interaction processes of multispheres including lithosphere, atmosphere, cryosphere, and biosphere during late Ediacaran glaciation.