Just as the host nation was desperately trying to corral more than 190 countries towards unity at talks in Belem, delegates ended up having to flee the short-lived blaze.
The fire broke out in the pavilion area of COP30, where groups showcase their efforts, prompting an evacuation across the site.
It was swiftly put out and 13 people were treated for smoke inhalation, officials said, with the cause thought to be an electrical fault.
But it will make the hard task of negotiations even harder, and they had already missed a self-imposed deadline to wrap up the first batch of deals on Wednesday evening.
Representatives have travelled from all corners of the globe to get together in the same room to try to solve some of the world’s biggest challenges.
The UN climate body (UNFCCC) has not yet confirmed when the site will reopen.
Talks were stuck on how to close the gap between the level of warming the world is on course for, compared to that which governments previously agreed would be a better, safe level.
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COP30 – why is it so controversial?
The most controversial solutions being discussed for this first agreement are the future of fossil fuels and the delivery of finance to help developing nations switch to clean energy and cope with the impacts of climate change they did little to cause.
About 80 countries have been lobbying for a plan or “roadmap” for how to “transition away from fossil fuels” – a pledge made at COP28 two years ago but which has subsequently been swept under the carpet.
Another dividing line was how rich countries, which generally have done more to cause climate change, should help poorer countries cope with more extreme weather that tends to hit them hardest.
Previous funding promises have materialised late or not in the form promised.
And for the first time critical minerals – vital for green technology like EVs and solar panels – may make it into one of the COP decisions to come later in the week.
