A Swiss study has found that using carbon dioxide removal alone to mitigate agricultural emissions is likely to increase food costs.
Carbon dioxide removal – or CDR – is often touted as a solution for industries that can’t easily reduce their emissions.
What is carbon dioxide removal?
- Also called negative emissions technology, CDR is a range of methods of removing carbon dioxide from the atmosphere
- Methods range from growing more trees and algae, to absorbing or capturing CO2 with certain chemicals and minerals
- Some methods (like reforestation) are well-established, while others (like absorbent mineral coatings) are still in the testing phase and might not work at a large scale
- These technologies are likely to be necessary to limit global warming to below 2°C, but they’re also not capable of being the sole solution
- Economic costs vary widely, depending on the technology – some afforestation could be as low as US $2 per tonne of CO2 removed from the atmosphere, while other sequestration technologies could be as high as US $3000 per tonne
- This study estimated an overall cost of US $150 per tonne of CO2 removed from the atmosphere
The agricultural sector, which produces a lot of methane and other non-CO2 greenhouse gases, has the opportunity to offset some of its emissions through CDR by doing things like wide-scale tree planting, and investing in more complex negative emissions technologies in other areas.
A new study, published in PLOS ONE, set out to determine if the global agricultural sector could offset all its emissions through CDR. The researchers used computer modelling to predict warming from agricultural emissions under different scenarios to 2050, as well as the expected costs of mitigation tactics.
They also examined the impact of methane and other greenhouse gases compared to carbon dioxide. CO2 removal is the only really feasible negative emissions technology, so a sector that makes a lot of non-CO2 greenhouse gases needs to consider how they equate to carbon dioxide. Two tonnes of CO2 might need to be removed from the air to mitigate the effect of one tonne of methane emitted, for instance.
The researchers found that if the sector offset all of their emissions with CDR and didn’t try any other mitigation techniques, the cost of food would rise dramatically. In the United States, the cost of beef would rise by 41%, rice by 14% and milk by 40%.
There are a range of methods for lowering agricultural emissions. Research published in the same journal today suggests that seaweed might reduce methane production in cattle, for instance. But given the rate of growth in the agricultural sector, these techniques are still underdeveloped.
“Albeit technically feasible, curbing non-CO2 agricultural emissions faces several challenges,” write the authors in their study.
The researchers emphasise that the agriculture sector needs a broader approach to emissions reduction, with CDR as a supporting factor. “To reduce this burden, as well as the risk of relying on unfeasible or unsustainable rates of CDR, strengthening efforts to mitigate agricultural emissions within the limits to food security should remain a climate policy priority,” they conclude.
Ellen Phiddian is a science journalist at The Royal Institution of Australia.
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