First a heat wave, then continuous rain: Was that still weather or is it already climate?

Highlights: Climate researchers are trying to find an answer to this question. They are looking at how much more likely it has become that certain extreme weather events have become more frequent or less frequent due to man-made climate change. The simultaneous heat waves throughout southern Europe would have been "practically impossible" without human greenhouse gas emissions, according to the scientific findings. Almost two-thirds of adults in this country are afraid of extreme weather. More than half of those surveyed say that the federal government is doing too little in terms of climate policy to protect people in Germany.

First it is hotter than average, then it hardly stops raining: Many people have the impression that there has never been such extreme weather as in July in the past. Climate scientists know the facts.

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Heavy rain and flooding in Slovenia, the third heat wave of the summer in Spain and weeks of rainfall in large parts of Germany. It feels like the weather is getting more and more extreme.

O-Tones:
"You have already experienced a lot of rain, but this year already a lot. Also, that in between there is a lot of rain, then a short sun, then rain again and then sun again, and that's really very changeable.«
"It's the first time I've been to Hamburg, but in France it's hotter and hotter and it's cold here, but it's still pleasant to be outside."

Just a perceived truth or is the weather going crazy more and more often? Climate researchers like Karsten Haustein are trying to find an answer to this question.

Karsten Haustein, University of Leipzig:
"We are looking at how much more likely it has become that certain extreme weather events have become more frequent or less frequent due to man-made climate change, i.e. due to warming, in order to assess the risks, including what we will face in the future, so to speak."

Attribution research is the name of this field of science. But first, let's take a look at the climate basics, explained by the expert himself.

Karsten Haustein, University of Leipzig:
"Weather is what happens every day, so to speak. And if we now take many, many years of weather on average – usually we're talking about 30 years – then we're talking about climate. And climate change is when a warming trend can actually be observed in the 30 years and, of course, over many 30-year periods strung together in this way, i.e. over, let's say, 50, 100 years. And that's exactly what we're observing."

In order to draw conclusions from the climate to the weather, attribution researchers work with models of a future world from which they have "excluded" climate change. They then look at specific extreme weather events – let's take the heat wave in July – in the real world and in climate models. The rest is mathematics.

Karsten Haustein, University of Leipzig:
"And we can say that heat waves have often become more likely by a factor of 10, 20, 30. In other words, what used to be a two-week heat wave that occurred every 50 years now happens every second or third year."

This is also the conclusion of a recent highly regarded attribution study from Great Britain: heat waves like the recent one are to be expected regularly in the current climate crisis: every 15 years in North America, every ten years in southern Europe and every five years in China.

According to a recent survey, almost two-thirds of adults in this country are afraid of extreme weather events in Germany. More than half of those surveyed say that the federal government is doing too little in terms of climate policy to protect people in Germany from this. Only 30 percent believe that the protection is sufficient.

Karsten Haustein, University of Leipzig:
"But we also have to sensitize the population and I think that is the decisive aspect. That is, when such a heat wave occurs, tell the older vulnerable people: You have to do this and that, drink a lot, try to ventilate cleverly, be prepared with maybe really a reasonable air conditioning system."

The observations, calculations and conclusions of the climate researcher therefore prove the feeling of many people right: Something is changing. The frequent weather extremes this summer are the effects of climate change – science can say that with a high degree of probability. The simultaneous heat waves throughout southern Europe would have been "practically impossible" without human greenhouse gas emissions, according to the scientific findings.

According to Haustein, it is now a matter of adapting to extreme weather – and preventing every additional tenth of a degree of global warming. And you don't even need extensive attribution research for that. Because as soon as we as humanity no longer cause CO2 emissions, the global temperature will not rise any further.

Karsten Haustein, University of Leipzig:
"It wouldn't go down again. It stays where it is, and the higher we get, the higher the temperature at which we are "trapped". But after that, if we go to zero, mind you, it will not rise arbitrarily. So we always have it in our own hands. And that's what's always in the back of my mind, so to speak: we all have solutions, we know how to do it and we just have to do it.«

First a heat wave, then continuous rain: Was that still weather or is it already climate?

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