Emergence of the Southeast Asian islands as a driver for Neogene cooling

Abstract

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, atmospheric pCO2 would have been significantly higher than preindustrial values, remaining above the levels necessary for initiating Northern Hemisphere ice sheets.

Mineral Dust Coupled With Climate‐Carbon Cycle on Orbital Timescales Over the Past 4 Ma

“…This may be because the controlling factors of atmospheric CO 2 concentration are very complex. This complexity stems partly from the fact that it is not just the marine biological pump that influences CO 2 , and CO 2 is also influenced by terrestrial silicate and basalt weathering (e.g., Park et al, 2020;Raymo & Ruddiman, 1992), volcanic eruptions (e.g., Berner et al, 1983), the extent of Southern Ocean sea ice (e.g., Marzocchi & Jansen, 2019), and oceanic ventilation and stratification (e.g., Moy et al, 2019;Roberts et al, 2016). These factors may explain the decoupling between atmospheric CO 2 concentrations and global ice volume over the 3-2 Ma period (Figure 1b1).…”

Latitudinal land–sea distributions and global surface albedo since the Cretaceous

“…4A), combined with contributions from weathering of obducted ophiolites from Tethyan arc-continent collisions in the broader tropics (Jagoutz et al, 2016;Macdonald et al, 2019), may have initiated and sustained the decline in atmospheric pCO 2 levels and associated greenhouse temperatures that culminated with the onset of Antarctic glaciations at the EOT (34 Ma) with amplification from ice albedo feedback (DeConto and Pollard, 2003) and served to lock-in the Late Cenozoic Ice Age. Northern hemisphere glaciations later in the Neogene may been fostered by enhanced CO 2 consumption in the most potent weathering region today: the Indonesia and Borneo areas of SE Asia plus New Guinea, high relief arc terranes that converged to straddle the tropical humid belt (Dessert et al, 2003;Kent and Muttoni, 2013;Park et al, 2020) (Fig. 6B).…”

Monsoon‐Enhanced Silicate Weathering as a New Atmospheric CO2 Consumption Mechanism Contributing to Fast Late Miocene Global Cooling

“…The interactions between tectonics and climate related to the Tibetan Plateau (TP) uplift, Asian monsoon circulation, Cenozoic global cooling, and atmospheric CO 2 consumption are intriguing issues that have been discussed since the late 1980s (Raymo, 1988), but the tightness of these links and the magnitudes of their importance have been widely debated over 3 decades (e.g., Caves Rugenstein et al., 2019; Clift et al., 2008; France‐Lanord & Derry, 1997; Lenard et al., 2020; Macdonald et al., 2019; Park et al., 2020; Raymo & Ruddiman, 1992). In particular, a new compilation of globally distributed sea surface temperature records reveals that fast late Miocene cooling occurred synchronously in both hemispheres at ∼7–5.4 Ma and that this period of rapid cooling was superimposed on the late Miocene long‐term gentle cooling trend (Hebert et al., 2016).…”