UN: World Will Overshoot 1.5°C — COP30 Faces Urgent Call to Declare Failure and Act Fast

World Set to "Overshoot" 1.5°C as COP30 Opens in Belém

The UN has confirmed that the planet is now essentially certain to overshoot 1.5°C of warming above pre-industrial levels, a shift that dominates climate talks as leaders gather for COP30 in Belém, Brazil. With global tensions, economic uncertainty and a US administration sceptical of climate science diverting political attention, emissions remain too high and ambitions too weak to avoid an overshoot.

UN Secretary-General António Guterres has warned that crossing 1.5°C in the coming years is now unavoidable, but he urged nations not to abandon the Paris Agreement’s safer aims. “The path to a livable future gets steeper by the day. But this is no reason to surrender,” he said as delegations arrived in the Amazon city.

“We must peak emissions immediately, scale up renewables and protect forests and oceans — and then deploy carbon removal quickly after reaching net zero,” Guterres said.

Scientists note that every tenth of a degree beyond 1.5°C magnifies costly and dangerous impacts — drought, heatwaves, wildfires and floods — and increases the risk of triggering major tipping points. Johan Rockström, director of the Potsdam Institute for Climate Impact Research, told AFP that humanity may face roughly 50–70 years above 1.5°C before temperatures could be pulled back down, meaning a prolonged period of heightened risk for food systems, freshwater supplies and global security.

Why “Declare Failure”?

The 2015 Paris deal set a goal of keeping warming “well below” 2°C and pursuing efforts to limit it to 1.5°C. Many scientific scenarios that limit long-term warming to close to 1.5°C nonetheless rely on a temporary overshoot followed by large-scale removal of carbon dioxide from the atmosphere. The Intergovernmental Panel on Climate Change (IPCC) had previously said emissions needed to peak around 2020 and fall sharply by 2030 to minimize overshoot. With emissions still rising and 2024 marking the first full year above 1.5°C, several scientists now urge honesty: acknowledge missed timelines, then redouble action.

“The first thing we need to honestly communicate to humanity, but also to all political leaders in the world gathering in Belém, is that we have to declare failure,” Rockström said — not as resignation but as a spur to accelerate mitigation and adaptation.

Risks, Tipping Points and Uncertainty

The IPCC warns that exceeding 1.5°C raises the chances of widespread melting of mountain glaciers and ice sheets that hold enough frozen water to lift oceans by metres over long timescales. Tropical coral reefs — vital nurseries for marine life and the livelihoods of roughly 200 million people — are already at acute risk and may be hitting tipping points. Many ecosystems and human systems are sensitive to both the peak temperature and the duration of any overshoot; how long they can endure is uncertain and varies regionally.

Negative Emissions and the Role of Natural Sinks

To bring temperatures back down after an overshoot, most pathways rely on a mix of fast emissions cuts, large-scale rollouts of renewable energy, protection and restoration of forests and oceans, and deployment of negative-emissions technologies such as afforestation, bioenergy with carbon capture and storage (BECCS) and direct air capture. Climate Analytics argues that a huge deployment of cheap solar and wind could ultimately return warming toward ~1.2°C by 2100 under its most ambitious scenario — but even that pathway likely involves an overshoot to at least ~1.7°C for decades.

Crucially, these scenarios assume natural sinks — forests and oceans — will continue to absorb about half of human CO2 emissions. In October, the World Meteorological Organization reported a record jump in atmospheric CO2 and warned that land and oceans may be becoming less effective at soaking up carbon. That raises the stakes for rapid emissions cuts and for making negative-emissions options operational at scale.

What Policymakers Can Do Now

• Declare the missed timelines honestly, and translate that into far stronger near-term targets.
• Immediately accelerate the deployment of renewables and phase out fossil fuels.
• Scale up protections for forests, mangroves and marine ecosystems that store carbon and support resilience.
• Invest in proven and emerging carbon-removal technologies while ensuring safeguards for land and communities.

Scientists and UN officials emphasize that an overshoot is not a signal to give up, but a warning to act faster and more ambitiously. “We’re now in a very risky space,” said Bill Hare of Climate Analytics — and every year of delayed action compounds the costs and risks for people and ecosystems worldwide.