Do Enhanced Weathering and DAACS Support Paris Agreement Targets?

1/23/20230 min read

Parties to the 2015 Paris Agreement (the “Paris Agreement”) have agreed to work toward restricting global warming to well below 2°C above pre-industrial levels, and to endeavour to maintain this increase to 1.5°C (Article 2(1)(a) Paris Agreement). Parties also pledged to enhance climate adaptation and build climate resilience and the prevalence of technologies involving low greenhouse gas emissions, while safeguarding food production (Article 2(1)(b) Paris Agreement), and to direct funds toward these strategies (Article 2(1)(c) Paris Agreement).

In essence, the key target of the Paris Agreement is to control and eventually stop global warming by sustainable adaptation, mitigation.

In order to fulfil this target and to compensate for ongoing emissions of carbon and other greenhouse gases, researchers have developed negative emissions technologies such as enhanced weathering (“EW”) and direct air capture and carbon storage (“DAACS”).

EW involves the acceleration of natural processes within the carbon cycle, such as the alkalinization of the ocean or soil by the application of calcium or magnesium carbonate minerals (EASAC 2018:23).

The EW carbon removal process is permanent (EASAC 2018:23), and the mineral silicates required are abundantly and naturally available (EASAC 2018:23). Further, EW has been identified to have greatest potential in warmer sub-tropical countries and regions including India, Brazil, and Southern China which, given their large populations and role in international climate governance, presents significant opportunity for progress toward the Paris target (Strefler et al 2018:8).

However, there are doubts as to the sustainability of EW and therefore its effectiveness in contributing to the Paris target. EW operations can demand large amounts of energy, land, and water, and may necessitate the mining of high volumes of minerals, all which could result in trade-offs against land use for food production, as well as lead to potential pollution and loss of environment or biodiversity (EASAC 2018).

To balance these competing concerns and further support the Paris target, at this initial stage in its development, adopting EW in controlled scales on existing small-scale arable farmland may deliver nutritional benefits to the soil (CarbonBrief 2018) while allowing for study of any potential impacts.

In DAACS, CO2 is absorbed from the atmosphere using liquid or solid sorbents, and then discharged in the form of a dense controlled stream for further handling (EASAC 2018:9).

DAACS is a more mature technology currently already in use (EASAC 2018:9). In situ application could also translate into minimized costs of transportation (EASAC 2018:25). However, as with EW, the potential competition with land for food production and environmental conservation (EASAC 2018:13) may engender misalignment with the food and sustainability aspects of the Paris target. DAACS can also be capital-, energy-, and water-intensive, and its effects on local proximal vegetation is currently uncertain (EASAC 2018), raising further doubt as to its sustainability.

Further research into more efficient and economical DAACS methods could increase the attractiveness of this technology from a Paris perspective. Questions as to scalability may also be addressed by deploying DAACS in conjunction with other mitigatory measures and lifestyle changes (Realmonte et al 2019:9).

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References:

  • CarbonBrief. (2018). ‘Guest post: How ‘enhanced weathering’ could slow climate change and boost crop yields’. Prof David Beerling. 19 February 2018. carbonbrief.org/guest-post-how-enhanced-weathering-could-slow-climate-change-and-boost-crop-yields/

  • European Academies Science Advisory Council (EASAC). (2018). ‘Negative emissions technologies - what role in meeting Paris Agreement targets?’. EASAC policy report 35 2018.

  • Realmonte, G., L. Drouet, A. Gambhir, J. Glynn, A. Hawkes, A.C. Köberle, and M. Tavoni. (2019). ‘An inter-model assessment of the role of direct air capture in deep mitigation pathways’. Nat Commun 10, 3277 (2019). https://doi.org/10.1038/s41467-019-10842-5

  • Paris Agreement to the United Nations Framework Convention on Climate Change, Dec. 12, 2015, T.I.A.S. No. 16-1104.

  • Strefler, J., T. Amann, N. Bauer, E. Kriegler, and J. Hartmann. (2018). ‘Potential and costs of carbon dioxide removal by enhanced weathering of rocks’. 2018 Environ. Res. Lett. 13 034010. DOI 10.1088/1748-9326/aaa9c4.