Soil carbon sequestration can contribute to climate change mitigation, but the carbon stored through agricultural practices may eventually be released back into the atmosphere. This non-permanence can compromise the climate integrity of using soil carbon removals to compensate for CO₂ emissions, whose warming effects persist over much longer timescales.

A new MARVIC policy brief, authored by Flora Desmet, Greet Ruysschaert, Jan Peter Lesschen and Jens Leifeld, addresses this issue by examining how the duration of soil carbon storage influences its climate benefits. The brief builds on climate modelling analyses presented in a MARVIC report recently made publicly available, providing recommendations for carbon farming policies and certification schemes.

The policy brief puts forward two main recommendations. First, temporary soil carbon removals should not be used to compensate for CO₂ emissions, whose climate impacts persist over much longer timescales. Instead, the authors suggest that temporary removals may be more appropriate for compensating for short-lived greenhouse gases such as methane (CH₄).

Second, the authors recommend encouraging longer carbon farming project durations and monitoring periods. Although temporary soil carbon sequestration can contribute to reducing peak global warming, its effectiveness depends on how long the carbon remains stored, future emissions pathways and the rate at which it is eventually released back into the atmosphere.

These recommendations aim to inform the development of carbon farming policies and certification schemes, particularly regarding permanence requirements, monitoring periods and the appropriate use of temporary carbon removals for emissions compensation.