What a difference a stinking hot day makes.

“It’s not the end of the world! Just stay cool and carry on,” advised the Monday front page of the U.K.’s Daily Express tabloid. “Listening to apocalyptic climate change pundits and the BBC, you’d think Britain was about to spontaneously combust,” scoffed an editorial in the hugely influential Daily Mail on the same day.

Their tunes changed quite dramatically following a Tuesday on which temperature records were shattered across the country, bringing an array of wildfires that even encroached on the capital’s outskirts. “Britain burns in 40.3C [104.5F] heat,” thundered this morning’s Express. “Nightmare of the wildfires,” read the Mail’s front page, over an image of homes combusting in the east-London village of Wennington.

Life comes at the Daily Express pretty fast… pic.twitter.com/ebU01noTbB

— Harry Wallop (@hwallop) July 19, 2022 Mail editorial yesterday… Mail front page today 🤔 pic.twitter.com/yVKLyee4HY

— Clifford Singer (@cliffordsinger) July 20, 2022 This heatwave is an example of what educators might call a teachable moment.

Brits learned that extreme heat will melt runways, buckle railway lines, knock out power grids, and even upset the cloud facilities of companies like Google and Oracle.

The French have been learning how soaring temperatures mean cuts to nuclear-energy output, because the river water needed for cooling is too warm. (As Fortune’s Tristan Bove notes in this piece on how extreme heat lowers solar-panel efficiency, the same problem can afflict other thermal power stations, including the coal- and gas-fired plants that contribute to all this heating.)

Meanwhile, drought-laden Germany may be about to revisit its 2018 nightmare of the Rhine being too low to transport goods such as food and car parts, which is just what we need during food-price and supply-chain crises. Yes, climate skeptics, it’s weather—but there’s overwhelming scientific consensus that human-driven climate change is making it more extreme, more frequently.

Even if one were to cold-bloodedly leave aside the human impact of this heat in Europe—the hundreds if not thousands of deaths; the losses of homes and livelihoods—that still leaves a significant economic cost, particularly when viewed in conjunction with the energy crisis, inflation and other ingredients of the stew we find ourselves in.

As London Business School economics professor Lucrezia Reichlin told the New York Times: “The combination of these things is all negative—the question is how negative it’s going to be.”

And this is just the start—the effects we’re seeing from a 1.2C global average temperature rise from pre-industrial levels. The odds are 50-50 that we’ll clear 1.5C just several years from now. Just imagine how costly our timidity and equivocation will prove to be then.