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Abstract. The numerical model GEOCLIM, a coupled Earth system model for long-term biogeochemical cycle and climate, has been revised. This new version (v 7.0) allows a flexible discretization of the oceanic module, for any paleogeographic configuration, the coupling to any General Circulation Model (GCM), and the determination of all boundary conditions from the GCM coupled to GEOCLIM, notably, the oceanic water exchanges and the routing of land-to-ocean fluxes. These improvements make GEOCLIM7 a unique, powerful tool, devised as an extension of GCMs, to investigate the Earth system evolution at timescales, and with processes that could not be simulated otherwise. We present here a complete description of the model, whose current state gathers features that have been developed and published in several articles since its creation, and some that are original contributions of this article, like the seafloor sediment routing scheme, and the inclusion of orbital parameters. We also present a detailed description of the method to generate the boundary conditions of GEOCLIM, which is the main innovation of the present study. In a second step, we discuss the results of an experiment where GEOCLIM7 is applied to the Turonian paleogeography, with a 10 Myr orbital cycle forcings. This experiment focus on the effects of orbital parameters on oceanic O2 concentration, particularly in the proto-Atlantic and Arctic oceans, where the experiment revealed the largest O2 variations. 

Steep topography, a tropical climate, and mafic lithologies contribute to efficient chemical weathering and carbon sequestration in the Southeast Asian islands. Ongoing arc–continent collision between the Sunda-Banda arc system and Australia has increased the area of subaerially exposed land in the region since the mid-Miocene. Concurrently, Earth’s climate has cooled since the Miocene Climatic Optimum, leading to growth of the Antarctic ice sheet and the onset of Northern Hemisphere glaciation. We seek to evaluate the hypothesis that the emergence of the Southeast Asian islands played a significant role in driving this cooling trend through increasing global weatherability. To do so, we have compiled paleoshoreline data and incorporated them into GEOCLIM, which couples a global climate model to a silicate weathering model with spatially resolved lithology. We find that without the increase in area of the Southeast Asian islands over the Neogene, atmosphericpCO₂would have been significantly higher than preindustrial values, remaining above the levels necessary for initiating Northern Hemisphere ice sheets. 

As the world warms, there is a profound need to improve projections of climate change. Although the latest Earth system models offer an unprecedented number of features, fundamental uncertainties continue to cloud our view of the future. Past climates provide the only opportunity to observe how the Earth system responds to high carbon dioxide, underlining a fundamental role for paleoclimatology in constraining future climate change. Here, we review the relevancy of paleoclimate information for climate prediction and discuss the prospects for emerging methodologies to further insights gained from past climates. Advances in proxy methods and interpretations pave the way for the use of past climates for model evaluation—a practice that we argue should be widely adopted.