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Humanity鈥檚 goal of limiting global warming to 1.5掳C above pre-industrial levels, which has been totemic in climate policy for the past decade, is now almost certainly out of reach. Limiting warming to 1.6掳C has become the best-case scenario for climate action, with the hope of bringing temperatures back to 1.5掳C later in the century using technology to remove carbon dioxide from the atmosphere.

鈥�1.5掳C without overshoot is not attainable,鈥� says at the Potsdam Institute for Climate Research in Germany. 鈥淵ou definitely therefore need to prepare for one tenth, or potentially multiple tenths of a degree, beyond that target.鈥�

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Bertram and his colleagues came to this conclusion by running a series of models that accounted for realistic constraints in rolling out green technologies and implementing climate policies, as well as 鈥渆nabling factors鈥�, such as reduction in energy demand.

Green technologies like renewable energy have taken off dramatically in recent years, but the key constraint to rapid climate action is the ability of governments to roll out carbon-limiting policies such as carbon taxes, the team found.

Some countries simply don鈥檛 have the infrastructure or the bureaucracy to effectively enforce policies like carbon pricing, says Bertram. 鈥淓ven if we see a massive shift in the coming years politically, we still can鈥檛 get around these hard facts,鈥� he says. 鈥淚t takes regulation for some of these solutions and you can鈥檛 expect all countries to have perfect regulation.鈥�

Once this is accounted for in modelling, the best-case scenario we can hope for is limiting peak warming to 1.6掳C, says Bertram. Even that will require huge political will from higher-income countries that have the greatest hope of taking climate action, he says. 鈥淲e are very far from that world, politically.鈥�

Three years of high temperatures will mean we have breached 1.5掳C

The aim to limit global warming to 1.5掳C is based on long-term average temperatures, but analysis shows that if three years cross the threshold, it is almost certain that the target has been missed

In fact, the researchers say it is more likely than not that we won鈥檛 be able to limit warming to 1.6掳C. There are a wide range of uncertainties, but they calculate the chance of succeeding at between 5 and 45 per cent. Success rates increase at 1.7掳C, 1.8掳C and so on. 鈥淭he world needs to be prepared for the possibility of an overshoot of the 1.5掳C limit by at least one and probably multiple tenths of a degree even under the highest possible ambition,鈥� they write in their paper.

Team member at Imperial College London insists the paper shows 鈥渁 relatively positive picture鈥�. He points out that the models suggest warming can be held below 2掳C assuming governments continue to improve their institutional capacities, and green technology can be rolled out rapidly. 鈥淒espite taking into account aspects of feasibility, [it shows] warming can be kept to relatively low levels,鈥� he says.

This latest study reflects the growing scientific consensus that the 1.5掳C temperature target, agreed by countries in Paris in 2015, is now unachievable without emissions overshoot. The last update from the Intergovernmental Panel on Climate Change (IPCC) released in 2022 suggested a narrow path to limiting warming to 1.5掳C was still possible, but since then global emissions have risen.

Human activities have already increased average global temperatures by 1.26掳C above pre-industrial levels, with 2024 likely to be the first year that average temperatures surpass 1.5掳C of warming.

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at US non-profit Berkeley Earth says the paper 鈥渕ore or less states what has become a largely unspoken consensus in the community: that it鈥檚 too late to prevent warming from exceeding 1.5掳C in the coming decades鈥�.

But he stresses that warming below 2掳C is still plausible. 鈥淲hile it might be too late to avoid passing 1.5掳C in the coming decades, it鈥檚 not too late to limit warming to 1.6掳C. The world does not end at 1.5掳C, and every tenth of a degree matters in terms of the impacts to society, the natural world and future generations.鈥�

at the University of Ottawa, Canada, says the work now shifts the focus of the debate to whether 1.6掳C is achievable. 鈥淚t puts that number 1.6掳C out there. And that is what the debate is going to centre on now,鈥� he says. 鈥淎nd after 1.6掳C, if we surpass that, it鈥檚 going to be 1.7掳C.鈥�