In recent years, we’ve all felt that heat waves are occurring more frequently and lasting longer, but studies have measured the speed of these waves and compared their duration to what happened more than 40 years ago. Very warm air masses move 20% slower on average, and heat waves last 50% longer. It would be different: they are affected by extreme heat and regions that, in general, were “freed” from them.

Romania experienced June temperatures in the last days of March, but several regions of the world touched record heat, from the Sahel to East Asia and from Belarus to Japan. At thousands of weather stations around the world, the heat record for the month of March was broken.

• The history of heat in Romania

The study, published in the journal Science Advances, aims to calculate what has changed with devastating heat waves, how air masses move, which areas are most affected and how much various indicators have increased between 2016 and 2020 compared to the period 1979-1983. , when discussions about global warming were in their infancy.

One conclusion is that, on average, globally, the warm air masses that support heat waves are moving 20% ​​slower compared to four decades ago and are appearing much more frequently, trapping more people under the heat dome. .

• Why is the summer in the city getting harder and harder and what can happen next

The study, published in the journal Science Advances, is titled “Anthropogenic influences have increased the risk of long-lasting and slow-moving large continuous heat waves.”

On average, heat waves lasted eight days 40 years ago, and in recent years the duration has increased by four days to 12. Apparently, there have also been waves lasting 3-4 days, but also those exceeding 20 days.

Heat waves have become more frequent worldwide, from an average of 75 per year in 1979-83 to an average of 98 per year in 2016-2020. The data is global.

The speed of movement of air masses during a heat wave has decreased the most in Europe and Asia, so longer and longer periods of temperatures that significantly exceed the norm often occur. The scale of heat waves increased most in North America and Australia, both in terms of temperatures and in areas affected by excessively hot weather.

Heat waves are reaching farther, reaching places that were relatively free of frequent episodes of extraordinary temperatures in the past. South America in particular experienced incredible heat last year, even in winter (temperature 39 C in winter).

Various atmospheric currents are weaker, especially in summer, so their slowed activity means less movement of air masses, and this “translates” into the fact that heat waves stay longer in some areas, very warm air is not replaced by cooler masses. The fever does not go away for several days.

Residents of cities, where the consequences of the “heat island” are increasingly felt and where nights with unbearable temperatures are increasingly common in the summer, suffer greatly.