'Carbon sequestration' often misused - can have unintended consequences
The concept of carbon sequestration is often misused. This can lead to misleading conclusions and exaggerated expectations about its climate impact, according to a new study from the EJP SOIL research program.
Without clear definitions of key climate concepts, we risk drawing misleading conclusions when it comes to climate change mitigation strategies. These are the recent findings of the research project CarboSeq in EJP SOIL.
The researchers analyzed 100 scientific articles on soil carbon to find out how carbon sequestration and similar concepts are used. They found that only four percent of the articles had used the term carbon sequestration correctly, according to an accepted definition based on the IPCC, among others. Furthermore, 13 percent of the articles equated carbon sequestration with carbon stocks, which is incorrect. Carbon stocks are the size of the carbon reservoir, while carbon sequestration is the net removal of carbon dioxide from the atmosphere.
"If you don't distinguish the concepts, it can lead to climate policy decisions not leading to the intended effects, which is of course problematic" explains Thomas Kätterer, professor at SLU and one of the researchers behind the study.
The results also showed that measures leading to carbon sequestration are often misinterpreted. A measure that aims to increase carbon storage in carbon-rich soils often leads to reduced carbon loss, which has a positive climate impact, but does not create negative emissions.
"We need to create negative emissions through land use change and management measures to compensate for the anthropogenic emissions that remain in the atmosphere even after we have reached the net-zero emissions target in 2045" says Thomas Kätterer.
Moreover, carbon sequestration measures do not always lead to climate change mitigation, if carbon leakage and emissions of other greenhouse gases are taken into account. The effect of a particular measure on carbon sequestration decreases over time. This is important to keep in mind when policymakers and other stakeholders evaluate the impact of climate action, according to the researchers.
The researchers propose a series of definitions related to soil carbon storage to increase the common understanding of the concepts within the framework of climate work (see table below). The hope is that this will provide a basis for ultimately developing climate strategies that actually lead to climate change mitigation.
The study
Term | Definition |
C sequestration in soils | Process of transferring C from the atmosphere into the soil through plants or other organisms, which is retained as soil organic carbon resulting in a global C stock increase of the soil (based on IPCC, 2001; Olson et al., 2014) |
SOC loss mitigation | An anthropogenic intervention to reduce SOC losses compared to a business-as-usual scenario |
Negative emission | Net removal of CO2-equivalents of greenhouse gases from the atmosphere |
Climate change mitigation | An anthropogenic intervention that reduces the sources or enhance the sinks of greenhouse gases (based on IPCC, 2021) |
SOC storage | The size of the SOC pool (i.e., SOC stock or SOC content) |
SOC accrual | An increase in SOC stock at a given unit of land, starting from an initial SOC stock or compared to a business-as-usual value (does not always result in climate change mitigation or C sequestration in soils) |
The table above defines different concepts related to soil carbon storage that the researchers propose to use. Perhaps they can help create a common understanding and provide a basis for developing climate strategies that have the intended effect.