气候变化领域集成服务门户(CCPortal): A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate

CCPortal

DOI	10.1016/j.epsl.2020.116181
	A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate
	Krissansen-Totton J.; Catling D.C.
发表日期	2020
ISSN	0012821X
卷号	537
英文摘要	The balance between carbon outgassing and carbon burial controls Earth's climate on geological timescales. Carbon removal in carbonates consumes both atmospheric carbon and ocean carbonate alkalinity sourced from silicate weathering on the land or seafloor. Reverse weathering (RW) refers to clay-forming reactions that consume alkalinity but not carbon. If the cations (of alkalinity) end up in clay minerals rather than in the carbonates, carbon remains as atmospheric CO2, warming the climate. Higher silicate weathering fluxes and warmer temperatures are then required to balance the carbon cycle. It has been proposed that high dissolved silica concentrations resulting from the absence of ecologically significant biogenic silica precipitation in the Precambrian drove larger RW fluxes than today, affecting the climate. Here, we present the first fully coupled carbon-silica cycle model for post-Hadean Earth history that models climate evolution self-consistently (available as open source code). RW fluxes and biogenic silica deposition fluxes are represented using a sediment diagenesis model that can reproduce modern conditions. We show that a broad range of climate evolutions are possible but most plausible scenarios produce Proterozoic warming (+5 K relative to without RW), which could help explain the sustained warmth of the Proterozoic despite lower insolation. RW in the Archean is potentially more muted due to a lower land fraction and sedimentation rate. Key model uncertainties are the modern reverse weathering flux, the rate coefficient for RW reactions, and the solubility of authigenic clays. Consequently, within the large uncertainties, other self-consistent scenarios where Proterozoic RW was unimportant cannot be excluded. Progress requires better constraints on parameters governing RW reaction rates including explicit consideration of cation-limitations to Precambrian RW, and perhaps new inferences from Si or Li isotopes systems. © 2020 The Authors
关键词	carbon cycle climate Precambrian reverse weathering silica weathering
英文关键词	Carbonates; Earth (planet); Open source software; Open systems; pH; Positive ions; Reaction rates; Silica; Silicates; Silicon; Uncertainty analysis; Weathering; Atmospheric carbon; Carbon cycles; Carbonate alkalinity; climate; Geological timescales; Precambrian; Sedimentation rates; Silicate weathering; Climate models; carbon cycle; deposition; diagenesis; paleoclimate; Proterozoic; silica; silicon; weathering
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202708
作者单位	Department of Earth and Space Sciences, cross-campus Astrobiology Program, University of Washington, Seattle, United States
推荐引用方式 GB/T 7714	Krissansen-Totton J.,Catling D.C.. A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate[J],2020,537.
APA	Krissansen-Totton J.,&Catling D.C..(2020).A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate.Earth and Planetary Science Letters,537.
MLA	Krissansen-Totton J.,et al."A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate".Earth and Planetary Science Letters 537(2020).