Global Carbon Budget for 1.5°C Will Be Exhausted in Three Years, Major Scientific Report Warns

The world has approximately three years left before it exhausts the carbon budget required to keep global warming below the 1.5°C threshold, according to a major international scientific assessment published Thursday.[1][5]

The latest Indicators of Global Climate Change (IGCC) report, authored by over 70 scientists and published in the journal Earth System Science Data, reveals that human-induced warming reached 1.37°C above pre-industrial levels in 2025.[5][6]

The remaining carbon budget—the total amount of carbon dioxide humanity can still emit while maintaining a 50% chance of limiting warming to 1.5°C—has shrunk to just 130 gigatonnes.[1][2]

With global greenhouse gas emissions hitting a record 56.8 billion tonnes of CO2 equivalent annually, researchers warn that this budget will be entirely depleted by 2029 if current trends hold, effectively closing the window on the Paris Agreement's most ambitious goal.[3][6]

"A key indicator is the Earth's energy imbalance, which measures how fast heat is accumulating in the climate system," noted Professor Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds and lead author of the study.[5]

This energy imbalance has more than doubled since the 1970s and is now at a record high, driving accelerated sea-level rise and intensifying marine heatwaves that threaten global food production and coastal security.[2][5]

Paradoxically, recent successes in combating global air pollution are contributing to the accelerated warming. Declines in sulfur dioxide emissions—which historically had a cooling effect by reflecting sunlight away from the Earth—are unmasking the full warming potential of accumulated greenhouse gases.[6]

The dire scientific update arrives just as climate diplomats from around the world convene in Bonn, Germany, for the UNFCCC's June Climate Meetings (SB64).[4][7]

The Bonn negotiations serve as a critical stepping stone to prepare the policy packages and frameworks for the COP31 summit, scheduled for November in Antalya, Türkiye.[7]

Negotiators are tasked with fleshing out the "Belém-Antalya Mechanism," a framework designed to facilitate a just transition away from fossil fuels, while also managing the political realities of inflation, high energy costs, and geopolitical instability.[3][4]

As the 1.5°C target slips out of reach, the diplomatic focus is increasingly shifting toward adaptation and the operational delivery of the Fund for Responding to Loss and Damage, which aims to compensate vulnerable nations for irreversible climate impacts.[2][7]

Local and regional leaders are also converging in Bonn for the Daring Cities dialogues, arguing that national climate pledges remain abstract without the funding and authority for municipalities to implement resilience strategies on the ground.[8]

"As we look ahead to COP31... this is a critical moment to strengthen the role of local and regional governments within the global climate architecture," stated ICLEI Secretary General Gino Van Begin, emphasizing the need to translate scientific findings into actionable urban policies.[8]

The convergence of the IGCC report and the UN meetings underscores a pivotal transition in global climate policy: moving from the theoretical design of emission targets to the concrete, often painful realities of economic implementation and disaster adaptation in a rapidly warming world.[1][4]