The United Nations says the world is going to pass the 1.5°C warming limit, ending the chance of reaching that goal without an overshoot. The warning came in recent reports from the United Nations Environmental Programme, with the best available path now pointing to a temporary rise above the limit before temperatures fall again.
That path is still open, but it demands cuts on a scale countries have not yet delivered. The scenario gives the world a 66 percent chance of keeping warming to a maximum of 1.8°C and an even chance of returning below 1.5°C by the end of the century.
Why 1.5°C Is Now Expected to Be Passed
The UN acknowledged that keeping warming below 1.5°C is no longer viable. Its report puts the reason plainly: “Decades of insufficient climate action makes exceedance of 1.5° C unavoidable.” The UNEP account also says, “The chance to keep global warming below 1.5°C with no overshoot is gone.”
There is an important detail behind those statements. Temperatures averaged over a few decades indicate that the world has technically not passed the limit yet, even though the current El Niño event appears exceptionally strong and will almost certainly mean that temperatures have gone over 1.5°C for a shorter period.
That makes this look less like one sudden breach and more like the start of a new period. The UN relies on temperature records showing that the long-term limit has not yet been exceeded, but temperatures are stubbornly disinterested in dropping much after hot years. It is likely that the world is now at the beginning of the period when the 1.5°C goal is passed.
The difference matters because the target is based on a long-term average, not one hot month or one hot year. At the same time, crossing the threshold temporarily still carries consequences. The UNEP report says every additional fraction of a degree and every additional year above 1.5°C raises the risk of irreversible changes and devastating human impacts.
The Narrow Route Back Below 1.5°C
Returning below the limit would require greenhouse gas emissions to fall by 18 percent by 2030, 45 percent by 2035, and 69 percent by 2040, all compared with 2025 levels. The best-case scenario also includes massive carbon removal, which would pull carbon dioxide from the atmosphere after emissions decline.
Current national plans fall far short of that pace. Full implementation of existing nationally determined contributions, or NDCs, would reduce emissions by only 5-8 percent by 2030 and 11-15 percent by 2035 relative to 2025 levels. Those cuts do not match the reductions needed to limit the overshoot and return to 1.5°C.
The projections show how much the outcome depends on what governments do next. If countries follow current policies, warming could reach 2.8°C within the century. If they fulfill all existing emissions reduction pledges, warming would be limited to 2.6°C.
Those figures are worse than last year’s projections. The change reflects the withdrawal of the US from the Paris Agreement and revised estimates of historical emissions. President Trump’s move to pull the US from the Paris Climate Agreement took effect in January 2026.
Trump signed an executive order to withdraw the US from the agreement soon after taking office last year. He had also withdrawn the US during his first term, before Biden rejoined the pact. The latest withdrawal now forms part of the policy picture used in the newer projections.
What Happens After the Threshold
Passing 1.5°C does not mean climate action has lost its value. It changes the task from preventing every overshoot to cutting peak warming and bringing temperatures down. The lower the peak, and the shorter the time spent above the limit, the lower the risks described in the UN report.
Inger Andersen put that challenge this way: “So, we must pull out all the stops to minimize peak warming and return to 1.5°C by the end of the century.” The goal now depends on fast emissions cuts, followed by carbon removal on the scale required by the scenario.
The choice is not between success and failure in one step. A world at 1.8°C is different from one at 2.6°C or 2.8°C, and every fraction of a degree matters. The UN’s message is stark, but it also points to a measurable response: cut emissions sooner, reduce the overshoot, and keep the path back below 1.5°C alive.
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