In a stark warning, scientists have revealed that efforts to remove carbon dioxide (CO2) from the atmosphere will not be enough to prevent catastrophic climate change if global temperatures exceed the critical threshold of 1.5 degrees Celsius. The research, published in the journal Nature on Wednesday, emphasizes that relying on carbon removal technologies cannot substitute for immediate and ambitious emissions reductions.
The Intergovernmental Panel on Climate Change (IPCC) has previously suggested that carbon dioxide removal (CDR) could slow warming by extracting accumulated greenhouse gases from the atmosphere, especially if the 1.5 degrees Celsius limit is breached. However, the new study highlights that even if CDR is scaled up, it cannot reverse other irreversible impacts of climate change, such as sea level rise and disruptions to ocean circulation.
“Even if you’ve brought temperatures back down again, the world we will be looking at will not be the same,” said Carl-Friedrich Schleussner of Austria’s International Institute for Applied Systems Analysis, one of the study’s authors.
The researchers point out that reducing temperatures from their peak may be more challenging than anticipated. Melting permafrost and shrinking peatlands could release additional greenhouse gases like methane, further accelerating warming and counteracting CDR efforts.
CDR encompasses a range of techniques aimed at extracting CO2 from the atmosphere, including natural solutions like afforestation and ocean algae, as well as technological innovations that directly capture CO2 from the air. Currently, CDR capacity removes about 2 billion tonnes of CO2 annually. To meet global climate goals, this figure needs to increase to between 7 and 9 billion tonnes, according to a separate report released in June.
However, the potential for scaling up CDR is limited. “If we are starting to use land exclusively for carbon management, this can strongly conflict with the other important roles of land, be it biodiversity or food production,” said Joeri Rogelj of Imperial College London, another co-author of the paper.
The study underscores that even under the most optimistic emissions reduction scenarios, some degree of temperature overshoot is likely. The IPCC’s latest assessment report allows for an overshoot of up to 0.1 degrees Celsius. Reversing this would require the removal of approximately 220 billion tonnes of CO2. An overshoot of 0.5 degrees Celsius would necessitate removing over a trillion tonnes.
“The risks the world exposes itself to from an overshoot are much larger than acknowledged,” Rogelj warned. “Only through ambitious emissions reductions in the near term can we effectively reduce the risks from climate change.”
Reference(s):
Carbon removal no solution if world misses warming target, study finds
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