Pre-Cenozoic paleoclimate responses to astronomical forcing

Astronomical insolation forcing is now well-established as the underlying metronome of Quaternary ice ages and Cenozoic climate carbon-cycle feedback mechanisms. However, its effects on earlier Eras (Mesozoic, Paleozoic, and pre-Cambrian) are less understood. In this presentation, I will evaluate various pre-Cenozoic modes of response to astronomical forcing, and provide an overview of the Earth System components that were particularly sensitive to astronomical forcing under evolving boundary conditions. Subsequently, the role of astronomical forcing in pacing the global carbon cycle in the Devonian warmhouse and Cretaceous hothouse worlds is discussed. Both periods are characterized by recurrent ocean anoxia and remarkably similar hypotheses exist regarding how astronomical forcing could have amplified a nutrient surplus (from chemical weathering and volcanism, respectively) to tip the ocean system into anoxia. The Triassic-Jurassic boundary cyclostratigraphy illustrates the importance of precession-scale time-control to understand feedback mechanisms and cause-and-effect chains at a resolution that is relevant for making analogies with the present-day. Finally, this presentation provides an outlook on the need for a coordinated approach, using so-called astrochronozones, to establish a fully astronomically-calibrated timescale for the Phanerozoic. Overall, I will highlight the need for a more comprehensive understanding of the role of astronomical insolation forcing in shaping Earth's climate over geologic time.