Extreme temperatures! Why is it so hot?

Last year’s summer stood out because almost a third of the northern hemisphere was affected by high temperatures for a particularly long time. “It was very unusual,” explained Omar Baddour, head of the World Meteorological Organization (WMO) Climate Watch department in Geneva. This summer of 2023, with the heatwave that arrives this week with extreme temperatures, is on its way to being just as hot or even hotter. Because?

more than 60,000 people died in Europe from the heat of the summer of 2022

The summer of 2022 was the hottest ever recorded in Europe. There were successive intense heat waves that broke temperature records, drought and forest fires.

A study led by the Barcelona Institute for Global Health (ISGlobal), a center promoted by the ”la Caixa” Foundation, in collaboration with the French National Institute for Health and Medicine Research (Inserm), estimates that between May 30 and September 4, 2022 there were 61,672 deaths attributable to heat.

The data proves that temperatures were above average throughout the summer, with higher incidence from mid-July to mid-August. Within that period of just over a month there was an intense pan-European heat wave, between July 18 and 24, to which a total of 11,637 deaths are attributed.

Italy and Spain, the countries most affected by the heat

The country with the highest number of deaths attributable to heat throughout the entire summer of 2022 was Italywith a total of 18,010 deaths, followed by Spain, with 11,324, and Germany, with 8,173.

What happened globally? From Southeast Asia to China, the US, Africa and Europe heat and drought records have been set everywhere and the forests have burned in regions that normally had little risk of wildfire.

Almost everywhere it is said that it has never been so hot for so long. Countries like Germany experienced the sunniest summer, but also one of the hottest and driest.

CLIMATE CHANGE MAKES EXTREME TEMPERATURES MORE LIKELY

“Climate extremes have always existed,” says WMO’s Baddour, “but it is clear that climate change will make them more frequent and intense.”

Network World Weather Attribution, led by climatologist Friederike Otto at Imperial College London, has determined that extreme temperatures are 30 times more likely in some places due to climate change.

In 2022, the hot July in Britain, with peaks of over 40C would likely have been 4C colder without global warming since the industrial revolution, according to the network.

Climate change not only leads to higher average temperatures, but also it also alters the circulation patterns of air currents in the atmosphere that affect the climate.

“The driver of air circulation is the temperature difference between cold polar air and warm air in the equatorial region,” says Baddour. Because the polar regions have become warmer, the temperature difference is less, and as a result, the engine is weaker.

This influences the typical so-called planetary waves. Waves have less variability, Baddour says, which is why weather conditions sometimes last for weeks, like the 2022 heat in Europe. When we enter a heat wave this summer, it’s more likely to be a long one.

What will happen after the hottest spring?

During the last week of April 2023, local temperatures in many regions of Spain, Portugal, Morocco and Algeria were up to 20ºC higher than normal for this time of year. In Portugal and mainland Spain, the national record for the month of April was broken by a very wide margin, with 36.9 °C and 38.8 °C, respectively, temperatures reached in the southernmost parts of the countries.

While Europe and North Africa have experienced increasingly frequent heatwaves in recent years, recent heat in the western Mediterranean has been so extreme as to be rare even for today’s warmer climate. These extreme high temperatures had not been predicted by climate models.

The fact that extreme heat increases faster than climate models simulate is a known problem in summer in Western Europe. It is estimated that when the planetary average temperature has risen 2 °C above pre-industrial levels, the average temperature in heat waves will increase by 1 °C, but it is possible that this estimate is conservative.

We just have to prepare for the heat. You have to cool the cities with green and blue shaded spaces (with water). Institutions have to design early warning systems and offer instructions. Each person has to learn to take care of themselves and the most vulnerable people.