Flash floods, such as those that struck Germany, Belgium and the city of London in July, will become more common as the climate crisis worsens. This is the warning issued by a group of British scientists: floods caused by summer downpours will become more frequent, and no city in England is safe.

What climate extremisation is

This is not the only warning to have emerged in recent weeks, which have seen at least two continents grappling with particularly severe weather conditions. Some Swiss researchers have published a study revealing how the occurrence of extreme weather events, including heatwaves similar to the one that recently affected the United States, is becoming increasingly likely.

Specifically, these record-breaking heatwaves will be two to seven times more likely over the next three decades, and three to 21 times more likely in the period between 2051 and 2080, unless CO2 levels fall immediately. The areas most at risk, according to the researchers, are the densely populated regions of North America, Europe and China.

"One of the main effects of climate change is precisely climate extremisation, whereby weather phenomena tend to become intense or even extreme more frequently," explains Serena Giacomin, meteorologist and climatologist, and president of Italian climate network. "An intense weather phenomenon is a calamitous phenomenon that can have negative effects in terms of damage and also casualties; an extreme phenomenon, on the other hand, is one that falls outside the climatic statistics of a given area."

The case of the United States

On the subject of the United States, Noaa (National oceanic and atmospheric administration) released the country's climate averages in May — data updated every ten years that on the one hand allow meteorologists to establish which temperatures or precipitation levels are record-breaking, and on the other enable residents and tourists to get a sense of the climate of a given region, to understand how to dress, when to sow seedlings in the garden, and so on.

This information makes it possible to build a precise picture of the climatic evolution of a territory: over time, US maps have become increasingly "red", that is, warmer. A clear change can be seen between the 2020 map and that of 2010: practically every part of the United States has become warmer. The south-west has become drier, while rainfall has increased on the east coast.

A hundred years ago there were always floods, there were always droughts, but they were less frequent and less violent, so something has genuinely changed, and what has objectively changed is that we have a warmer planet, and all that heat then transforms into energy and into more violent weather phenomena.

Paolo Corazzon, meteorologist at 3bmeteo.com

Data such as these are fundamental for meteorologists. "Forecasts are increasingly precise and accurate, but individual episodes are becoming difficult to track and predict, so it is quite a challenge for meteorologists too — one that cannot always be won, because there is always that element of atmospheric unpredictability which becomes a little more pronounced with these phenomena," explains Paolo Corazzon, meteorologist at 3bmeteo.com.

"These extremely violent and intense phenomena are also very localised. If we think about events in Italy over recent days — such as the exceptional hailstorms over northern Italy — you really only need to move a few kilometres and you go from hailstones the size of golf balls to almost full sunshine, so they are truly very circumscribed."

The example of Germany

In Germany, several factors combined to make the floods so devastating. First of all, it appears that the level of soil saturation before those rains arrived was already very high, and this is an important factor. If the ground is already saturated, it is unable to absorb additional rainfall. The rains were clearly intense, but above all prolonged, because the low-pressure system present was almost stationary.

Heat and humidity are the fuel of a storm.

Serena Giacomin, president of Italian climate network

Furthermore, "we were coming from a period of very significant thermal anomalies, including in Lapland and the North Sea. And this is perhaps what should give us the most pause — the fact that if you have thermal anomalies of as much as 10–15 degrees more in Lapland, that very warm air does nothing but feed energy into the incoming weather systems, bearing in mind that warm air is capable of storing a greater quantity of moisture than cold air. Heat and humidity are the fuel of a storm. This is perhaps the closest link one can find between the intensity of a weather event and global warming," clarifies Serena Giacomin.

Climate change also causes changes in ocean currents and atmospheric currents. Not to mention that the destruction of ecosystems fundamental to the planet's hydrological cycles, such as the Amazon, is profoundly altering precipitation patterns.

And in Italy?

Humidity and heat. These are precisely two reasons why the Italian peninsula is at risk. "Italy is a morphologically challenging country, where violent hydrogeological events are a daily occurrence: we have the two highest mountain ranges in Europe, the Alps and the Apennines, and mountains play a fundamental role in atmospheric circulation and therefore, frequently, are the site of violent weather phenomena. We have the Mediterranean, a warm sea that feeds energy into the atmosphere. It is no coincidence that Italy is the European country with the highest number of tornadoes," continues Paolo Corazzon.

When it comes to the areas to be monitored, nowhere is spared. The north remains the zone where particularly intense rainfall events are most frequent, sitting as it does halfway between the so-called temperate Mediterranean climate and the European one, but similar episodes have affected, on multiple occasions, every corner of our country.

Being frightened is fine, but it's not enough

The Swiss scientists who predicted the intensification of extreme weather phenomena used the worst-case scenario for their models, because in fact, despite the climate policies that have been adopted, CO2 levels in the atmosphere have not yet fallen. With a rapid and immediate reduction in emissions, the risk is reduced by 80 per cent.

Giving up means doing nothing; giving up means having to deal with these phenomena — it doesn't mean changing our habits a little. If an all-encompassing solution is hard to find, there is always room to improve, every single day.

Serena Giacomin, president of Italian climate network

We should take it as a positive sign: "It is no longer enough to interpret data solely as warning messages," Giacomin concludes. An attitude like that can lead to empiricism or even denialism, because society has no desire to take on a problem like climate change. "On the contrary, we must use scientific data as a tool for making decisions: it's fine to be frightened, but then we need to act."

How? Experts have been telling us for some time: through mitigation and adaptation. That is, by reducing pollution and adapting our territory to the new climatology. Our cities were built for the climate of the past, but things have changed by now. It follows that inhabited centres must evolve too.

Meteorology is certainly providing enormous help, and it will become ever more fundamental in the future.

Paolo Corazzon, meteorologist at 3bmeteo.com

Climatologists and meteorologists must present a united front in this battle. Climatologists are indispensable for developing adaptation policies. Meteorologists will become increasingly essential in the emergency situations that we will find ourselves facing ever more frequently. With accurate weather forecasts, intense phenomena can be anticipated, allowing territories and populations to be put on alert and lives to be saved.

We must play our part, and among the most effective actions we can take are reducing our meat consumption and choosing sustainable investments. It is reassuring, however, to know that we have experts we can rely on: rather than seeing them as "harbingers of doom," let us learn to see them as the people who can truly save us.