Carbon sequestration in soils and climate change mitigation—Definitions and pitfalls

Abstract

The term carbon (C) sequestration has not just become a buzzword but is something of a siren's call to scientific communicators and media outlets. Carbon sequestration is the removal of C from the atmosphere and the storage, for example, in soil. It has the potential to partially compensate for anthropogenic greenhouse gas emissions and is, therefore, an important piece in the global climate change mitigation puzzle. However, the term C sequestration is often used misleadingly and, while likely unintentional, can lead to the perpetuation of biased conclusions and exaggerated expectations about its contribution to climate change mitigation efforts. Soils have considerable potential to take up C but many are also in a state of continuous loss. In such soils, measures to build up soil C may only lead to a reduction in C losses (C loss mitigation) rather than result in real C sequestration and negative emissions. In an examination of 100 recent peer‐reviewed papers on topics surrounding soil C, only 4% were found to have used the term C sequestration correctly. Furthermore, 13% of the papers equated C sequestration with C stocks. The review, further, revealed that measures leading to C sequestration will not always result in climate change mitigation when non‐CO2 greenhouse gases and leakage are taken into consideration. This paper highlights potential pitfalls when using the term C sequestration incorrectly and calls for accurate usage of this term going forward. Revised and new terms are suggested to distinguish clearly between C sequestration in soils, SOC loss mitigation, negative emissions, climate change mitigation, SOC storage, and SOC accrual to avoid miscommunication among scientists and stakeholder groups in future.

On the importance of time in carbon sequestration in soils and climate change mitigation

“…This definition is based on the definitions provided by IPCC (2001) and Olson et al (2014). We agree with Don et al (2023) that this term is often used misleadingly, which may lead to erroneous or biased quantifications of the role of soil in climate change mitigation.…”

“…The article of Don et al (2023), contrasted with previous literature, suggests that we are still far from a scientific consensus on a definition of carbon sequestration in soils and natural carbon sinks.…”

“…A clear definition of carbon (C) sequestration in soils is necessary to accurately quantify the role of soil in climate change mitigation. Don et al (2023) proposed defining carbon sequestration as " [the] Process of transferring carbon from the atmosphere into the soil through plants or other organisms, which is retained as soil organic carbon (SOC) resulting in a global C stock increase of the soil". This definition is based on the definitions provided by IPCC (2001) and Olson et al (2014).…”

Impact of bare fallow management on soil carbon storage and aggregates across a rock fragment gradient

“…To analyze the contribution of C and N stored in particulate and MOM fractions, we applied a combined density and size fractionation slightly modified according to Kölbl and Kögel-Knabner (2004). The term C storage is used in this study synonymously to the C content as well as the proportion and contribution of bulk soil C stored in OM fractions according to Don et al (2023). After the addition of 3 Na 2 WO 4 ⋅ 9WO 3 solution of 1.8 g cm −3 , the floating organic particles were obtained as free POM (fPOM) and the fraction was isolated.…”

Response of maize yield to changes in soil organic matter in a Swedish long‐term experiment

“…Agricultural practices that diversify crop rotations by including cover crops, and perennial plants or promote C inputs to the soil in other ways have been found to increase soil organic carbon (SOC) and soil organic matter stocks . This can lead to SCS, that is, the net transfer of carbon from the atmosphere to the soil (Don et al, 2023), which, in turn, may increase yield potentials, improve food security, the efficiency of agricultural inputs and promote the efficient use of soil, one of our primary natural resources (Rumpel et al, 2020). It was estimated that 0.08-0.4 Pg C year À1 or even more if further technical development in plant breeding is considered, can be globally sequestered in upland agricultural soils (Paustian et al, 2016).…”