Portugal has recorded its highest May temperature on record, with the mercury reaching 41.5°C in the central town of Mora on 27 May. The previous record of 40.5°C, set in 2014, has been exceeded by a full degree, a margin that climate scientists describe as 'significant' in the context of a warming planet. The heatwave, which has gripped much of southern Europe, has prompted the UK Met Office to issue an unusual warning: the continent may be approaching a 'climate tipping point' for extreme heat events.
Dr. Helena Vance, Science & Climate Correspondent, explains: 'The term tipping point is often reserved for systemic shifts, like the collapse of the Greenland ice sheet. But the Met Office is now using it to describe the rapid escalation of regional heat extremes. This is not a gradual trend, it is a step change.'
Portugal's record comes as part of a wider pattern. Spain experienced its hottest May on record, with average temperatures 4°C above the 1981-2010 baseline. Parts of southern France have seen temperatures exceed 35°C, nearly 10°C above seasonal norms. The European heatwave, which began in mid-May, has been driven by a high-pressure system that has drawn hot air from North Africa. But the underlying cause, Vance notes, is the accumulation of greenhouse gases in the atmosphere. 'The atmosphere can now hold more heat. That is basic physics.'
The UK Met Office's warning is based on climate models showing that what was once a one-in-50-year heatwave in Europe could occur as frequently as every 10 years by mid-century. Dr. Vance: 'We are not just seeing records broken, we are seeing the distribution of extremes shift. The signal of climate change is no longer a whisper, it is a shout.'
The implications are profound. Portugal's record temperature coincides with a severe drought that has depleted reservoirs and heightened wildfire risk. Elsewhere in Europe, the heat has disrupted agriculture, with crop yields expected to fall. 'This is not an abstract problem,' says Vance. 'It is about food security, water supply, and the habitability of regions that have been temperate for centuries.'
The concept of a tipping point is contentious, but the Met Office's use of the term reflects a growing consensus that the planet's climate system is undergoing nonlinear changes. Vance concurs: 'We have been observing a linear increase in global average temperature. But the frequency of extreme events is accelerating. That is a nonlinear response. And it is exactly what we should expect if we are approaching a system threshold.'
As Europe bakes, the need for rapid decarbonisation becomes ever more urgent. 'Every fraction of a degree matters,' Vance concludes. 'Portugal's record is a vivid reminder of what a 1.2°C warmer world looks like. It will only get worse unless we act now.'
