New estimates of the storage permanence and ocean co-benefits of enhanced rock weathering.
New estimates of the storage permanence and ocean co-benefits of enhanced rock weathering.
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DOI：
10.1093/pnasnexus/pgad059
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发表时间：
2023-04
期刊：
影响因子：
--
通讯作者：
Reinhard CT
中科院分区：
文献类型：
--
作者：
Kanzaki Y;Planavsky NJ;Reinhard CT
在未来一个世纪要避免人为气候变化带来的许多最严重后果，很可能需要开发“负排放技术”——即能导致地球大气中二氧化碳净清除（CDR）的方法。然而，碳循环内部的反馈对CDR对大气中二氧化碳的长期影响存在内在限制，而且这些限制可能因CDR技术不同而有所差异，目前对此的约束还很薄弱。在此，我们利用一组地球系统模型，通过明确量化增强岩石风化（ERW）过程中碳在海洋中的长期储存量（相对于等效的调控排放情景），对增强岩石风化实现二氧化碳清除的效率提供了新的见解。我们发现，尽管在所有情况下，面对CDR时二氧化碳向大气的回流都很显著且随时间变化，即使是对于直接清除和地下储存也是如此，但与增强岩石风化相关的最初捕获的碳的泄漏量远低于目前的假设。此外，与等效排放轨迹相比，增强岩石风化给海洋表层增加的净碱度导致海水碳酸盐矿物饱和度显著提高，这对钙化海洋生物是一种协同效益。这些结果表明，增强岩石风化过程中海洋潜在的碳泄漏在整个增强岩石风化生命周期中是一个很小的组成部分，并且可以对其进行严格量化，并纳入大规模增强岩石风化的技术经济评估中。
Avoiding many of the most severe consequences of anthropogenic climate change in the coming century will very likely require the development of “negative emissions technologies”—practices that lead to net carbon dioxide removal (CDR) from Earth's atmosphere. However, feedbacks within the carbon cycle place intrinsic limits on the long-term impact of CDR on atmospheric CO2 that are likely to vary across CDR technologies in ways that are poorly constrained. Here, we use an ensemble of Earth system models to provide new insights into the efficiency of CDR through enhanced rock weathering (ERW) by explicitly quantifying long-term storage of carbon in the ocean during ERW relative to an equivalent modulated emissions scenario. We find that although the backflux of CO2 to the atmosphere in the face of CDR is in all cases significant and time-varying, even for direct removal and underground storage, the leakage of initially captured carbon associated with ERW is well below that currently assumed. In addition, net alkalinity addition to the surface ocean from ERW leads to significant increases in seawater carbonate mineral saturation state relative to an equivalent emissions trajectory, a co-benefit for calcifying marine organisms. These results suggest that potential carbon leakage from the oceans during ERW is a small component of the overall ERW life cycle and that it can be rigorously quantified and incorporated into technoeconomic assessments of ERW at scale.
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