The world is facing a critical juncture in its battle against climate change. A leading scientist, Johan Rockström, has issued a stark warning: removing carbon dioxide from the atmosphere is now an essential step to prevent catastrophic climate tipping points. With global heating already projected to reach approximately 1.7°C (3.1°F) above preindustrial levels, even in the most optimistic scenarios, drastic measures are required.
Rockström, a prominent advisor to the UN and the Cop30 presidency, emphasizes the need to remove a staggering 10 billion tonnes of carbon dioxide from the air annually. Achieving this through technological means, such as direct air capture, would necessitate the creation of the world's second-largest industry, trailing only oil and gas, and incurring annual expenditures of roughly a trillion dollars. This endeavor must be undertaken alongside significant emissions reductions and could potentially lead to unforeseen consequences.
At a recent public event hosted by the Science Council, an advisory body established by the Belém Cop30 presidency, several renowned climate experts shared their insights. They predicted that within the next five to ten years, the world will surpass the 1.5°C target set by the Paris agreement. This milestone was temporarily breached in 2024, but UN scientists consider the goal violated only when the trend is confirmed over a 10-year average, coupled with forecasts for the subsequent decade, as explained by Thelma Krug, the council's coordinator.
Chris Field, a member of the council from Stanford University, stressed the importance of retaining the 1.5°C target, despite the overshoot. He highlighted the increased risk of dangerous tipping points in Antarctica, Greenland, ocean circulation, and the Amazon rainforest as global heating persists beyond this threshold. Coral reef systems are believed to have already crossed the point of no return at 1.5°C of heating.
Tim Lenton, an expert on tipping points from the University of Exeter, outlined the range of risks that are already imminent. He warned of even greater dangers looming ahead, particularly if there is a collapse of the Atlantic meridional overturning circulation system of ocean currents. "This would trigger other tipping points," Lenton emphasized, urging, "We must do everything we can to prevent this."
Field estimated that 200 billion tonnes of carbon dioxide would need to be removed from the atmosphere to cope with every tenth of a degree rise. He acknowledged that this could potentially manage a rise of two-tenths of a degree but cautioned that the process would be slow, expensive, and could lead to a wide array of unintended consequences.
There are several options for capturing carbon, each with its own advantages and drawbacks. The most effective and cost-efficient method is growing forests, which costs approximately $50 (£38) per tonne of CO2 removed, but this land cannot be used for other purposes like agriculture. The most expensive option is direct air capture, an industrial process that has yet to be implemented on a large scale, with costs starting at $200 per tonne. In between are riskier strategies like ocean fertilisation, which could disrupt marine ecosystems.
The Intergovernmental Panel on Climate Change (IPCC), the UN's primary climate science body, has initiated a study on various carbon removal mechanisms. Rockström expressed his desire for the Cop30 presidency to include carbon removal in its declarations, drawing attention to the risks and costs associated with this critical issue. He highlighted that Potsdam Institute modelling indicated that even with ambitious carbon removal efforts and strong government actions to reduce emissions, it would still only be possible to limit heating to between 1.6°C and 1.8°C. This would require far more stringent policies to reduce fossil fuel emissions than those currently implemented by governments, which would allow for a minimum of 2.7°C of global heating.
Despite the immense costs involved, Rockström emphasized that the alternative is even more devastating, with increased droughts, fire storms, and human suffering. "Every tenth of a degree matters," he said. "We are witnessing a rapid approach towards a dead end. Scientists continue publishing papers, but we are getting nervous. We are seeing truly worrying signs."
Scientists advocate for the inclusion of tipping point prevention in the global stocktake of the Cop process. Lenton welcomed the IPCC's study on these risks and emphasized the existence of positive tipping points, where social, economic, or technological drivers can push for change towards a more stable climate. He expressed optimism about the Cop30 presidency's willingness to engage, despite challenging political circumstances elsewhere.
"I'd love to think this Cop could be its own tipping point," Lenton said. "It should be, given that the tipping point risks are right in front of us, especially with the coral reef collapse and the Amazon suffering from extraordinary droughts and fires."
Unfortunately, the US, under President Donald Trump, has withdrawn from the Paris agreement once again and will not be part of any new alliances. Christiana Figueres, one of the architects of the Paris deal, expressed relief at the US's absence, addressing Trump with a playful "Ciao bambino!"
"I think it's actually a good thing," she told reporters. "They won't be able to engage in direct bullying. Honestly, the decarbonisation of the global economy is irreversible. Momentum is building to a point where it is simply unstoppable, with or without the US."
As the world navigates these complex challenges, Ethiopia has been named the expected host of Cop32 in 2027. However, the host for Cop31 next year remains uncertain, with neither of the two bidders, Australia and Turkey, showing any signs of backing down.
