While “carbon dioxide removal is necessary to meet the 1.5°C target,” the technique can’t substitute for deep emission cuts, and fast action on climate change will be needed to avoid the most harmful negative emissions technologies, The Sink and Mirror reports, in its summary of this week’s IPCC report on options for limiting average global warming to 1.5°C.
“All pathways that limit warming to 1.5°C rely on rapid emission cuts, combined with efforts to remove carbon dioxide from the atmosphere,” the specialty newsletter states, and “the amount of carbon dioxide removal needed, and the methods that can be used, depend on the level of emission cuts over the next few years.” It warns that “while removing carbon dioxide is also necessary, it cannot make up for weak emission cuts.”
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The four 1.5°C pathways in the IPCC report underscore the point, the Sink and Mirror notes: “If emissions have not fallen by 2030, the world might have to remove nearly 1,200 billion tonnes of carbon dioxide by the end of the century—about 30 times current annual emissions. But with a 58% carbon dioxide cut by 2030, relatively little carbon dioxide removal would be needed.”
Editor Leo Barasi focuses much of his report on the IPCC’s assessment of today’s carbon capture technologies. The scientific body “concludes that, while burning biomass then capturing and storing the emissions (BECCS) offers the most potential for carbon dioxide removal, this would have major demands for land and water, causing problems for food production and biodiversity,” he notes. “Tree planting could be less disruptive (though still needs a lot of land), but can remove less carbon dioxide.”
Relying on reforestation might be sufficient if greenhouse gas emission cuts can move quickly enough. But “with slow emission cuts, large-scale BECCS may be the only way of removing enough carbon dioxide, and this could require an area more than twice the size of India for growing bioenergy crops.”
Barasi notes that the IPCC has little to say about solar radiation management, a newer and highly controversial approach that has been put forward as a negative emissions option. “Uncertainties and knowledge gaps in the science, along with political and social barriers to deployment, mean the report did not treat sunlight reduction as an alternative to emission cuts and carbon dioxide removal as a way of meeting the 1.5°C target,” he states.
