Governments and businesses have placed excessive reliance on the future removal of carbon dioxide (CO2) from the atmosphere, instead of taking immediate action to reduce emissions and phase out fossil fuels. A critical examination of this approach reveals that the current understanding of the damaging consequences of carbon dioxide removal is incomplete. This research study, published in Science, highlights the overestimation of the carbon dioxide removal potential as reported by the Intergovernmental Panel on Climate Change (IPCC). The researchers argue that the heavy reliance on bioenergy with carbon capture and storage, as well as tree-planting, poses significant risks to people, food security, and natural ecosystems.
To analyze the viability of carbon dioxide removal methods, the researchers examined the most recent IPCC reports and the pathways for limiting global warming to 1.5°C. By incorporating biodiversity and human livelihood risks into the various scenarios, the study discovered that the sustainable thresholds for land-based carbon dioxide removal using bioenergy crops, forestry, and ecosystem restoration are significantly lower than the deployment expectations presented in the IPCC reports. The lead author, Alexandra Deprez, emphasizes the potential threats to food security, human rights, and natural ecosystems, concluding that the proposed scale of carbon dioxide removal efforts risks overstepping multiple planetary boundaries in potentially irreversible ways.
High Risks for Agriculture, Livelihoods, and the Environment
The levels of carbon dioxide removal considered feasible by the IPCC come with high risks for agriculture, livelihoods, and the environment. Due to the limited land available on our planet, the large-scale implementation of carbon dioxide removal methods would inevitably lead to detrimental consequences. Prof. Paul Leadley warns that focusing on technical and economic potentials alone is insufficient. Instead, issues such as biodiversity, freshwater use, and food security should guide the limitations of carbon dioxide removal efforts.
The latest IPCC mitigation report, AR6 WGIII, acknowledges the need to address the ambitious climate goals set out by the Paris Agreement. To this end, it seeks to identify the technical and economic limits to carbon dioxide removal options. However, the proposed upper limits for bioenergy with carbon capture and storage and afforestation/reforestation would require an area three times the size of the United States to be dedicated to bioenergy crops or trees. Such a large-scale conversion of land would potentially lead to the food insecurity of over 300 million people. Additionally, existing climate commitments indicate that countries plan to produce double the recommended amount of fossil fuels in the next decade, further exacerbating the challenge. Dr. Kate Dooley emphasizes the importance of setting separate, transparent targets for emission reductions and removals, ensuring they align with climate and biodiversity commitments through the restoration and maintenance of natural ecosystems.
The paper proposes several crucial steps towards a sustainable approach to carbon dioxide removal. Firstly, estimating a sustainable carbon dioxide removal (CDR) budget based on socio-ecological limitations to prevent overstepping thresholds. Secondly, identifying viable pathways to limit global warming to 1.5°C that do not jeopardize sustainability CDR thresholds, focusing specifically on the near-term national climate plans. Lastly, the governance of carbon dioxide removal should allocate the limited sustainable supply to the most legitimate uses. The scientific community is urged to contribute to the upcoming cycle of IPCC reports, offering insights and analysis that address the interconnectedness of the climate and biodiversity crises.
The study highlights the critical need to reassess the current overreliance on carbon dioxide removal methods. While these methods may seem like a promising solution, they ultimately fail to address the pressing issues of climate change and biodiversity loss. The risks associated with large-scale carbon dioxide removal, including threats to agriculture, livelihoods, and the environment, cannot be ignored. It is imperative for governments and industries to establish separate targets for emission reductions and removals, prioritize the preservation and restoration of natural ecosystems, and seek sustainable solutions that do not exacerbate existing problems. Only through a comprehensive and critical analysis of carbon dioxide removal can we hope to make meaningful progress towards a sustainable future.
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