Global climate scientists are warning that removing large volumes of carbon dioxide from the atmosphere is now essential to prevent catastrophic tipping points, even under optimistic warming scenarios. Johan Rockström of the Potsdam Institute for Climate Impact Research emphasized that the world is on track to heat by about 1.7°C, meaning that roughly 10 billion tonnes of CO₂ must be extracted annually to stabilize the climate. He and other experts speaking at the inaugural public session of the Cop30 Science Council stressed that this massive undertaking would require building the world’s second-largest industry—surpassed only by oil and gas—and would cost around $1 trillion per year. Techniques such as direct air carbon capture offer one pathway, but these must accompany deep emissions cuts and come with substantial uncertainty and potential side effects.
Scientists at the event agreed that the world will overshoot the Paris Agreement’s 1.5°C target within the next decade, though the UN considers the threshold officially breached only after long-term temperature averages confirm a persistent trend. Despite this overshoot, Stanford University’s Chris Field urged global leaders to maintain the 1.5°C goal, warning that the duration and magnitude of time spent above it sharply increase the odds of triggering irreversible tipping points. These include destabilization of Antarctic and Greenland ice sheets, shifts in ocean circulation, Amazon rainforest dieback, and coral reef collapse—many of which may already be close to or beyond their limits.
Tim Lenton of the University of Exeter highlighted the serious risk of a shutdown in the Atlantic meridional overturning circulation, a change that could unleash a cascade of additional tipping points. Field added that roughly 200 billion tonnes of CO₂ would need to be removed for every 0.1°C of warming compensated. Even under ideal conditions, this approach could only offset about two-tenths of a degree, and attempts to scale solutions—whether reforestation, ocean fertilization, or direct air carbon capture—carry financial, ecological, and geopolitical challenges.
Nature-based solutions, particularly forest expansion, remain the cheapest form of carbon capture, costing around $50 per tonne but requiring vast tracts of land. In contrast, technological methods such as industrial direct air capture cost at least $200 per tonne and have never been proven at scale. The IPCC has launched new research into removal methods, and Rockström urged Cop30 leaders to formally incorporate carbon removal into their declarations as a way to highlight the profound economic and systemic risks now confronting governments.
Potsdam Institute modeling indicates that even with strong emissions reductions and aggressive removal—including technological and nature-based carbon capture—global heating is likely to settle between 1.6°C and 1.8°C. Current government policies, however, still steer the planet toward 2.7°C of warming. Scientists warned that failing to act will bring escalating droughts, fires, and human suffering, with every increment of warming increasing global danger.
As geopolitical complications shape the upcoming climate negotiations, experts emphasized that positive tipping points are also possible—social, technological, and economic shifts that accelerate climate solutions. While political conditions remain difficult, the Cop30 presidency may still help forge coalitions capable of addressing these rapidly approaching risks.
https://www.theguardian.com/environment/2025/nov/11/leading-scientist-says