Seventeen heatwaves already – and more to come. That’s what the Mallorca newspapers were reporting in early July, as holidaymakers endured day after day of punishing 35C-40C conditions. And they were right. Another unbearable heatwave arrived a fortnight later.

The waitress in Palma was in despair. At least you can go back to an aircon hotel, she told me. Her home was a small shared apartment with no air conditioning. “When I get home, I lie on the bed, put ice over my body and hope I get some sleep before returning to work,” she added.

“We used to get maybe a few days like this in August every year. Now it starts so much earlier and lasts so much longer. I have no idea why you want to come here in this heat.”

Ten million tourists visit Mallorca every year, with Brits jostling with the Germans as the biggest contingent. Airlines massively inflate their fares in July and August; hotels jack up their room rates; even the tabac in central Palma felt it could get away with charging €2.50 for a small plastic bottle of chilled water.

What do we get for our money? Beaches now so insanely hot they are effectively off-limits until 5.30pm or later. Hotel bedrooms where you hide from the sun with the aircon on full blast, knowing you’re contributing to climate destruction, but feeling you’ll pass out otherwise. Even Palma’s wondrous cathedral loses its charm when you’re faced with an entrance queue snaking out into the scorching midday sun, largely made up of refugees from the monstrous cruise ships in the bay.

Mallorca newspapers report the heatwaves. Photograph: Patrick Collinson

The Boeing 707, Lunn Poly and Judith Chalmers of Wish You Were Here gave us the cheap Spanish package holiday in the 1970s, and British families have been heading there ever since. Sun and cheap food and drink in Mallorca, or a washout week in Margate for about the same money? It was hardly a tough choice. Then, more recently, we’ve seen the huge expansion in weekend break tourism, encouraged by budget airlines and Airbnb.

But the climate crisis changes all that. A report last month attempted to visualise its impact on various cities around the world by 2050. Both Madrid and Athens will be more like present-day Fez in Morocco, the already high temperature in summer moving up by as much as another 6.4C.

I’m no stranger to the Spanish summer heat, having lived for a year in Madrid. “Seis meses invierno, seis meses infierno” is how Spanish friends described their capital’s climate. The alliteration doesn’t work in English, but it translates to “six months of winter, six months of hell”. But that was the 1980s; that “infierno” is going to be full-on Dante within a few years.

Margate is beginning to look rather more attractive. Spain, apart from the booze, is no longer the super-cheap destination it once was. The pound has fallen steeply, and may become permanently depressed post-Brexit. Holidays to Spain could turn into a financial disaster, with families paying a small fortune just to sit inside their hotels to escape intolerable conditions outside. Once is bad luck. But after your second or third holiday in unbearable heat, you won’t go again.

Parts of Palma have already sunk into decay, with many of the 1970s high-rises built during the package holiday boom now tawdry and dated. Will the British seaside resorts, that were so decimated by Spanish competition, revive over the next few decades? A hotel in Bournemouth could be a much better investment than a development in Benalmádena.

The report, that said Madrid will be engulfed by horrifically high temperatures, suggested London’s climate will, by 2050, become like Barcelona’s today. It was unfortunately worded, given how many commenters of the Daily Mail’s report seemed to think that “if this is climate change, great, bring it on”. If the climate changes that rapidly, then it’s not clear if much of London will be above water.

There is much discussion among environmentalists about how we reduce the climate impact of flights, either by rationing or by price.

Maybe neither will be necessary – we won’t go, because it’s just too damn hot.

p.collinson@theguardian.com