Due to global warming, it is getting warmer on average, but extremes are changing even more.
Do you remember the ten mark bills? They depicted Carl Friedrich Gauss (1777 to 1855), one of the greatest mathematicians of all time. On the back was the Gaussian bell curve that he had introduced. In addition to the decoration of banknotes, this is also used in many areas of natural science and technology, including climatology. Because it can explain to us why extremes should occur much more often with apparently moderate warming.
Take a wooden board and place nails on it at regular intervals, similar to a fakir seat cushion. Now you close the whole thing with a transparent cover and set it up vertically. Underneath you place several small containers close to each other and from above you let small balls fall through the nail forest in the middle.
The balls are randomly deflected left or right by the nails. When they arrive at the bottom, they flop into one of the collection containers. Most of the balls will probably end up in the middle containers, but some fall further outwards and very rarely it can also happen that one is only deflected in one direction and ends up falling into one of the outermost pots.
The resulting distribution in the pots is described by the normal distribution introduced by Gauss. It is always used when the deviations from the mean, i.e. the middle pot, are purely coincidental, but larger deviations are becoming increasingly unlikely. If you look at the average temperature in Germany over several years, you will also find the normal distribution here. Cool and warmer years seem to alternate at random.
Statistical distribution describes the probability of extremes occurring
For a few decades, however, systematic warming has been recorded, which corresponds to a shift in the drop point in our bed of nails experiment. This will systematically shift the distribution of the balls in the pots in one direction. The interesting question is how much the number of balls in the outer pots changes. Applied to the climate, this corresponds, for example, to particularly hot summers or mild winters.
The probability for these events corresponds to the area under the bell curve beyond a chosen temperature threshold. In the bed of nails experiment, this is the number of balls in the outer pots compared to the total. Due to the special shape of the bell curve, the number of balls on the outside changes significantly if you move the dropping point only slightly. Similarly, for example, the probability of hot summers or mild winters in this country increases significantly with an apparently slight increase in temperature.
For example, the probability that the mean temperature in August in Frankfurt am Main was above 22 degrees in 1901 was only 0.1 percent. Back then, such a hot August was only expected once a millennium. To date, the probability has risen to over 15 percent, which means that about every sixth August is currently this warm. An annual mean temperature of over 11.5 degrees was also expected in Frankfurt in 1826 only once in about 1000 years. Today, a higher value is measured every two years on average.