It is “shocking” how little people know about the danger of hot weather, the United Nations global chief heat officer has said, as high temperatures bake cities across the northern hemisphere and politicians backslide on climate promises.

A study this month found that extreme heat in Europe last summer killed 61,000 people, most of whom were women and older people. As well as killing people through heatstroke, hot weather can push the bodies of people with heart and lung disease into deadly overdrive.

“It’s total cognitive dissonance that this information is not common knowledge or part of our collective subconscious,” said Eleni Myrivili, the chief heat officer for the UN’s human settlement programme, who served the city of Athens in a similar role until June last year.

She said many people, particularly in the Mediterranean and Middle East, mistakenly believed they were used to hot weather and able to cope with it. “People are just starting to realise that this is another beast that we’re dealing with.”

Burning fossil fuels has made heatwaves hotter and more common. A recent study from the World Weather Attribution partnership found that heatwaves in July were 1C hotter in China, 2C hotter in North America and 2.5C hotter in southern Europe than if humankind had not changed the global atmosphere. The average maximum temperatures in North America and Europe would have been “virtually impossible” if humans had not heated the planet.

In Greece, where hot and dry weather has helped wildfires race across tourist-packed islands, the area burned this year is more than double the average for the same period over the previous 16 years. The country recorded its hottest July temperatures in half a century over the weekend.

“This morning, I woke up and there was smoke in my nose, and I heard there was a fire not too far away from here,” said Myrivili, who escaped 42C (108F) heat in Athens for a home in the countryside the day before. Firefighters soon put it out, she said.

“Constantly, we live with this fear of our forest burning, which is such a terrible kind of idea because it’s nature that we need more than anything to lower temperatures. The idea that our best ally, and our shield and weapons, is being demolished and destroyed – it’s really very painful.”

Myrivili, who also works for the US non-profit Adrienne Arsht-Rockefeller Foundation Resilience Centre, was appointed to the UN role in June 2022 as part of a partnership between the two organisations. The aim is to help cities across the world prepare for extreme heat and respond better when it arrives.

There are three key ways in which a city can keep people safe from heat, said Myrivili. The first is being aware, so people and institutions make hot weather a priority. The second is being prepared, so vulnerable groups are quickly found and kept safe – for instance, by reducing hours for outdoor workers and checking in on older people who live alone.

The third way, she said, is rebuilding cities to make them cooler by adding green spaces and water, and taking away space from cars. Cities are typically a few degrees hotter than their surroundings because of the heat released by fossil fuels and absorbed by infrastructure, such as asphalt roads and concrete car parks.

“We need to get rid of them and start putting in permeable surfaces, water elements and a lot of trees to make sure that we lower temperatures,” said Myrivili.

Global temperatures have risen by about 1.2C since the industrial revolution, making extreme heat stronger and more likely. World leaders promised at the Paris climate summit in 2015 to limit warming to 1.5C by the end of the century. However, they have implemented policies that put the planet on track for 2.7C.

“[The agreement in] 2015 was an important moment, there was a bit of momentum,” said Myrivili. “Then we lost our footing. And we should have been running.”

Temperatures in Europe have risen nearly twice as fast as the global average. Italy, Greece, Spain and Portugal – where residents are famed for long lifespans attributed in part to healthy diets and high levels of social contact – had the greatest share of their populations killed by heat in Europe last summer.

Before, said Myrivili, “we lived in a beautiful kind of climate where winters were cool and summers were hot, but we were excited for summer to come”. She added: “We all went outside and had these great big groups of people hanging out in public spaces, and making the city alive and making it vibrant.”

Now, she said, she worried for her 24-year-old daughter living in a world that will be increasingly divided into “air-conditioned and non-air-conditioned, survivable and non-survivable. It’s a nightmare to think about that.”