Biochar

Biochar has been used throughout history, mostly in tropical areas. Although the technology therefore already exists, and can be considered amongst the most technological ready amongst CDR measures (Möllersten and Naqvi, 2022), much new research is currently being done on the properties of specific production processes and materials. An extensive literature review by Elkhlifi et al. (2023) stressed the need to develop economically viable production methods, and encouraged further research into specific production and application procedures.

Although the measure seems promising, uncertainties remain about the extent of the scalability of biochar (Smith et al. 2023). Chiquier et al. (2022) comparative study of carbon removal technologies suggest biochar is relatively inefficient at sequestration, and risks decreasing in efficiency due to the decay overtime. Furthermore, if biochar is produced on regular agricultural land it can take up valuable space that would otherwise be used for food or energy purposes.

The technology already exists and will likely play some role in mitigating carbon emissions, but uncertainties remain about total effectiveness.

Although biochar has historically been mainly used in tropical areas, Lévesque et al. (2021) literature review shows certain specifically produced sorts are also beneficial to temperate areas. Since biochar application can have a multitude of other beneficial soil effects besides carbon sequestration, it might be beneficial to polluted areas in the Arctic. Studies by Karppinen et al. (2017) and Zahed et al. (2021) for example suggest biochar could be used to remediate soils that have been contaminated by hydrocarbons, especially if specific kinds of biochar production techniques are used. Tregubova et al. (2021) experimental study equally showed that biochar has a capacity to restore soils that were polluted by long term emissions of the nickel industry in the Kola peninsula.

Both the State of Carbon Dioxide Removal report and the IPCC AR6 wg3 report estimate a potential global carbon capture potential between 0.3 and 6.6 GtCO2/yr (Smith et al, 2023; IPCC, 2022). Although biochar will likely play an increasing role in global mitigation strategies, uncertainties however remain about the possible scale of mitigation, as uncertainties remain, for example around the potential warming effect of low-albedo biochar to soils (Meyer et al, 2012).

The cost of biochar application would be highly case dependent (Möllersten and Naqvi, 2022). The State of Carbon Dioxide Removal report estimates potential costs of 10 to 345 $/tCO2 (Smith et al. 2023). alongside the highly spread costing estimate, durability of sequestration should also be taken into consideration, with Chiquier et al.’s (2022) comparative CDR study finding that biochar is relatively inefficient at sequestration, and risks decreasing in efficiency due to the decay overtime.

As mentioned above, many studies indicate possible beneficial effects of biochar application for polluted areas. There might however be negative environmental effects of the production process, and unsustainable material harvesting (Smith et al. 2023; IPCC AR6, WG3 2022). Given the already occurring increase of natural and anthropogenic black carbon in the Arctic (Stubbins et al, 2015), large-scale application of biochar in the region should likely be further studied.

The IPCC AR6 WG3 report (2022) warns that poorly implemented biochar production and distribution risks causing adverse effects for local communities and ecosystems. However, biochar could also be greatly beneficial due to positive side effects on soil fertility and potential to mitigate certain toxins and increase drought resistance (Smith et al. 2023). A 2019 study by Keske et al. specifically showed that in the case of a majority indigenous inhabited remote area in Labrador, Canada, the practically free by-products of wood logging could be utilized for biochar production. The subsequent usage on the area's marginal soils could for some produce form an economic benefit and might improve food security. The authors furthermore argue that from an environmental justice standpoint, it could even be argued that the government should forward the high initial investments to create a biochar industry for a region that has been historically exploited.

The biochar would decay overtime.

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This would fall under national legislation.

Although public attention seems limited, and popular media references more limited as opposed to more spectacular geoengineering ideas, biochar is by far the most studied CDR ideas. There are many research projects, roughly 40% of all studies on CDR methods being biochar related, and around 50% of all CDR studies published in 2021 studying biochor (Smith et al. 2023).