40 C in June? Why Europe is roasting in another heat wave

Europe is baking.

Across much of the continent, temperatures have been soaring, reaching close to 40 C. And in some places, the sweltering heat is expected to stick around for a while yet.

In Madrid, the State Meteorological Agency (AEMET) is forecasting the heat wave to extend into next week.

Milan, Italy, is also expected to continue to roast, with temperatures forecast in the high 30s throughout the weekend, and possibly into next week. With the humidex, it will feel closer to 50 C.

"Normally, the words 'Germany,' 'June' and 'temperature of 38.6 C' don't really run together very well, but this is what we saw today," said Clare Nullis, spokesperson for the World Meteorological Organization, a UN agency.

However, Europe is no stranger to heat waves.

In 2003, a heat wave lasted from June to August, resulting in the deaths of 70,000 people, according to a study published 4½ years later. (Earlier estimates had pegged the death toll at 30,000.)

And just last year, another heat wave gripped the continent, leading to a regional drought.

But what's slightly unusual about what's happening now is the timing.

"We are seeing a heat wave which is unusually early," Nullis said. "We're still at the end of June, not into July and August when temperatures typically peak."

The culprit? Heat from northwest Africa that is making its way northward.

Of particular concern, Nullis said, is what may lie ahead. The 2018 heat wave was the result of something called a blocking pattern, when the jet stream causes a weather system to stall for days or even weeks. Nullis said she hopes that doesn't happen again in this case.

Links to climate change

While it's too early to say for certain that this recent heat wave is connected directly to climate change, Nullis said scientists are getting better at attribution studies that can do exactly that.

"We're still in the middle or even the beginning of this heat wave. What we can say is that it's fully consistent with what we expect with climate change," Nullis said.

On Wednesday, Germany's Potsdam Institute for Climate Impact Research (PIK) issued a statement that says the data clearly shows heat waves and other weather extremes are on the rise. 

"The hottest summers in Europe since the year 1500 AD all occurred since the last turn of the century: 2018, 2010, 2003, 2016, 2002," said Stefan Rahmstorf, PIK's co-chair of Earth system analysis. "Monthly heat records all over the globe occur five times as often today as they would in a stable climate."

Also concerning, scientists say, is that eastward-travelling circulation in the atmosphere over the Northern Hemisphere — including the jet stream, which is a driver of weather patterns — has slowed down. 

The focus may be on Europe at the moment, but Nullis said heat waves are on the rise across the globe and that trend will continue.

"Every summer, we also hear about American heat waves, Canadian heat waves, African heat waves, certainly Australian heat waves," she said.

According to Météo-France, the national meteorological service, the number of heat waves in France has doubled in the past 34 years and is expected to double again by 2050.

The World Meteorological Organization defines a heat wave as a stretch of five days where the daily maximum temperature is 5 C above the average.

Nullis said there is a silver lining in all of this: meteorological services and governments are becoming better at not only predicting heat waves, but also planning ahead in order to keep people safe. 

"2003 triggered a lot of action," she said. "A lot of lessons were learned from that tragedy — and it was a tragedy."

As Earth's temperature rises, she said, countries will need to find ways to cope and ensure the safety of society's most vulnerable members, children and the elderly.

"Heat waves are a major health problem," she said. "And they're not going to go away."