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Assessing Carbon Dioxide Removal methods amid uncertainty

soil carbon sequestration, biochar and harvested wood products as methods for climate change mitigation

Time: Fri 2023-03-10 14.00

Location: Kollegiesalen, Brinellvägen 8, Stockholm

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Language: English

Subject area: Chemical Engineering

Doctoral student: Alexander Olsson , Energiprocesser

Opponent: Universitetslektor Lowe Börjeson, Stockholm University

Supervisor: Universitetslektor Stefan Grönkvist, Energiprocesser; Universitetslektor Mathias Fridahl, Linköping University Unit of Environmental Change; Biträdande professor Anders Hansson, Linköping University Unit of Environmental Change

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QC 2023-02-15


Measures to sequester carbon dioxide (CO2) away from the atmosphere have become increasingly important in the discussion of which methods humans can employ to limit global warming. These measures, which are broad and varied, fall under the umbrella of Carbon Dioxide Removal (CDR) methods. CDR methods can be used to reach so-called net-zero targets, since targets are politically determined to allow for CDR methods to compensate for some emissions that are hard to abate.

Several CDR methods provide co-benefits in addition to mitigating climate change. They are therefore not pure climate measures. Using an interdisciplinary approach and a methodology including quantitative estimates and interview data, I investigate how some important CDR methods with co-benefits may be assessed and potentially supported by policy. Soil carbon sequestration using solar powered irrigation systems in the drylands of China, biochar-producing cookstoves in Tanzania, and biochar and wood-based panel production using forestry by-products in Sweden are CDR methods that I assess in their local context in this thesis.

To increase the ambitions towards reaching the climate goals set out in the Paris Agreement, some countries, such as Sweden, are looking to invest in international mitigation activities. This thesis illustrates that there is a heavy focus on measurable parameters when estimating the outcome of international climate change mitigation activities. However, unmeasurable uncertainties, such as political issues and economic rebound effects, tend to be neglected. These unmeasurable uncertainties are likely to be important and cannot be neglected if international mitigation activities, for example under Article 6 of the Paris Agreement, are to be used to reach net-zero targets.

Designing policy instruments that seek to encourage the use of CDR methods with co-benefits based on their ability to store CO2 may cause unintended consequences, such as inefficient use of resources. In addition, many of the co-benefits are not yet supported by scientific studies, which complicates policymaking. Despite often being considered win-win solutions, CDR methods with co-benefits face resistance since they often challenge current practices. In this thesis, I suggest various approaches to manage these uncertainties and challenges.