How much climate change in the current heat wave is burdening Europe and Germany these days? Weather experts are divided: on the one hand, they always assure that there were often very hot days in June, that is, in early summer. Above all: these heat waves lasting a few days are ‘weather’ – not ‘climate change’.
On the other hand, Claire Nullis, a spokeswoman for the World Weather Organization (WMO) in Geneva, under the impression of the current heat wave, stresses that the very high temperatures that spread from North Africa to southern Europe and reached Switzerland and Germany this weekend are fairly typical. In July or August – not for June.
Such extreme weather conditions will occur more frequently in the future due to climate change, Nullis says, unusually early and as intensely as it is happening in Europe. “Unfortunately, what we are seeing today is a prediction for the future.” This is due to the high concentrations of gases in the atmosphere that cause global warming.
In some parts of Spain and France, thermometers have risen more than ten degrees above average at this time of year, Nollis reports. Spain, Portugal, Hungary and Serbia are affected by drought.
The average temperature in Germany has risen by 1.6 degrees since 1881
As reported last year, data from the German Weather Service (DWD) showed that climate change is now having a strong impact on the weather in Germany – in some cases even to a greater extent than the world. A US Department of Defense (DWD) fact sheet showed that the last decade was two degrees warmer than the first decades of weather observations from 1881 to 1910.
[Lesen Sie zum Thema auch den Text von Jan Kixmüller auf Tagesspiegel Plus, auf dem dieser Artikel teilweise beruht: Wie der Klimawandel Deutschland verändert]
In general, the average temperature in Germany has increased by 1.6 degrees since 1881 – this value worldwide is 1.1 degrees lower. The frequency of extreme heat waves has clearly increased, while severe frosts have decreased, according to DWD: “Long-term phases with daily maximums of 30 degrees and above are a new phenomenon in some areas.”
Exactly one year ago, weather conditions in Germany had already led to “hot” days with maximum temperatures over 30°C and “tropical nights” almost everywhere. According to meteorological definitions, these are days when temperatures are above 30 degrees and nights when the temperature does not fall below 20 degrees Celsius.
Weather researchers speak of a “heat wave” when the average maximum temperature exceeds 30 degrees Celsius over a period of at least five consecutive days. This sign is currently likely to be missed because at least in Berlin and Brandenburg on Monday a drop in temperature to around 19/20 degrees is expected. But then, a gradual rise to 31 degrees should follow on Friday.
[Lesen Sie auch den T+-Artikel von Patrick Eickemeier, aus dem in diesem Artikel zitiert wird: Sommer, wie er früher keinmal war]
On the question of the extent to which heat waves are evidence of climate change, the Ministry of Social Development takes the position that climate changes become apparent only when long-term mean values of a more recent period are compared with those of older periods. The average temperature in Germany, which is 1.6 degrees higher than in 1881, contributes to the fact that threshold values are frequently exceeded, there are more hot days and more heat waves.
Heat waves are increasing in intensity and duration
The intensity and duration of heat waves have increased over the past 30 years, which is why Andreas Friedrich of DWD also discovered it. “Heatwaves are becoming more likely because of rising temperatures.”
This trend can be observed all over the world, and not only in Germany and Europe. However, the number of heat waves in Western Europe “has increased more than expected in the past two decades,” Diem Cuomo, who researches extreme weather events at VU Amsterdam and for the Dutch weather service KNMI, told Tagesspiegel on the occasion of a heat wave a year ago.
Two theories have been discussed in climate research as explanations beyond the greenhouse effect. On the other hand, the circulation of air currents in the atmosphere has changed. The jet stream that was used to cool Europe weakened, causing heat waves to last longer across the continent.
On the other hand, the soil in Europe has become drier in many places, which is why so little water can evaporate from it when it is warm. The cooling effect of evaporation is lost and the sun increases the temperature of the air. (with authors dpa and Tagesspiegel)