[S-GC36] 固体地球化学・惑星化学

[SGC36-06] Carbon mineralization potential for climate change mitigation in Oman and Pakistan

*Arshad Ali¹、Mohamed El-Ghali^1,2、Mohammad Kakar³、Iftikhar Abbasi²、Sobhi Nasir^1,2、Rehanul Haq Siddiqui⁴、Leonardo Nogueira⁵、Osman Salad Hersi⁶、Mohamed Moustafa²、Iffat Jabeen⁷、Nisar Ahmed⁸ (1.Earth Sciences Research Centre, Sultan Qaboos University, Oman、2.Department of Earth Sciences, Sultan Qaboos University, Oman、3.University of Balochistan, Pakistan、4.Saindak Metals, Pakistan、5.Federal University of Ouro Preto, Brazil、6.University of Regina, Canada、7.Project Management Institute, South Western Ontario Chapter, Canada、8.College of Economics and Political Science, Sultan Qaboos University, Oman)

キーワード：Carbon Mineralization, CO2 Sequestration, Climate Change, Ultramafic Rocks, Carbonate Minerals, Oman Ophiolite

Excessive greenhouse gas emissions, notably carbon dioxide (CO₂), contribute to global warming because the CO₂ emission-sink balance has been disturbed by the widespread use of fossil fuels since the industrial revolution. Following the Paris pledges, the Intergovernmental Panel on Climate Change (IPCC) established a target of limiting global warming to 1.5 °C above pre-industrial levels. Currently, global temperature is 1.1°C higher than the pre-industrial era (McKinsey.com). Based on current rates of anthropogenic CO₂ emissions, the global community will need to remove 100 billion to 1 trillion tons of CO₂ from the atmosphere by 2100 in order to limit global warming to 1.5°C. This means that with current carbon removal and storage policies, we may face the challenge of removing 2–20 billion tons of CO₂ per year starting in 2050. (Fox, 2021). Since the Paris Agreement, several mitigation strategies have been targeted, including renewable energy technologies, the decarbonization of major industries, and carbon capture and storage approaches.
Natural carbon mineralization (CM, image 1) involves the storage of atmospheric CO₂ as solid carbonates through the carbonation of ultramafic rocks (Ali et al., 2021). Such rocks are abundantly available worldwide (e.g., 60-600 trillion tons; Fox, 2021), offering a huge opportunity for the CM, as evidenced by two pilot projects: CarbFix (95% of the injected 250 tons of CO₂ turned into carbonate mineral within 2 years, Matter et al., 2016) and Wallulla (Signe et al., 2020). We recommend that the IPCC recognize the CM as a potential mitigation approach and that it be thoroughly discussed at the upcoming COP27 in Egypt for potential pilot project sites, including Oman, Pakistan, Alaska, Canada, California, New Zealand, and Japan. Here we focus on Oman and Pakistan because ophiolite units in both countries belong to the Late Cretaceous Tethyan Ophiolite Belt (Pearce, 1980). Oman offers 15000 km³ of mantle rocks (i.e., ultramafic rocks with Mg-, Ca-, and Fe-rich minerals) called the Oman Ophiolite, having roughly 3 km of thickness (Fox, 2021). Similarly, Pakistan hosts several ophiolite units at the NW margin of the Indian continent via the Waziristan-Muslimbagh-Bela Ophiolite suture zone, spanning an area of > 5000 km² (Siddiqui et al., 1996, Zaigham and Mallick, 2000, Kakar et al., 2014). The Oman Ophiolite is mainly comprised of olivine-rich peridotites, unlike Pakistan's ophiolite units, where peridotites are metamorphosed extensively into serpentine (Kakar et al., 2014), which has a higher carbon capture potential than olivine (Lacinska et al., 2017; Sandalow et al., 2020).
Oman and Pakistan are important countries for conducting CM pilot projects, with several potential sites for future CO₂ sequestration for a number of reasons: natural resources are abundant, accessibility to Central Asian republics in terms of cost reduction for importing engineering equipment and concentrated CO₂ due to the development of Duqum and Gwadar Ports. We recommend that the IPCC step up its efforts to mitigate climate change by undertaking regional collaborations in conducting the CM projects in Oman and Pakistan to achieve the Paris pledges sooner rather than later.
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