On the DWD's Summer Report 2023: In the midst of climate change

Fred Hattermann, hydrologist at the Potsdam Institute for Climate Impact Research (PIK), comments:

"The summer report of the German Weather Service underlines that we are in the middle of climate change. Although the summer was warmer than the long-term average, it was also wetter. This allowed the topsoil, which had been very dry due to the long drought in the late spring and early summer, to replenish. However, the deeper soil layers remain unusually dry in many regions of Germany, particularly in the east and south.

This year's precipitation cannot compensate for the precipitation deficit that has accumulated over the past few years. And due to the fact that this summer has also been warmer than average and radiation has also increased sharply, the water demand of vegetation is growing steadily, so we need more precipitation every year to compensate for this.

In addition, we have seen some extreme precipitation, especially in southern Germany, although our southern neighbors such as Austria, the western Balkans and Italy have been hit even harder. These precipitation masses originate from the Mediterranean region, where water surface temperatures are very high. This causes a lot of water to evaporate, and the resulting clouds and associated low pressure area move northeast over the Adriatic Sea and across the Balkans. In the last few days, this track of precipitation could be observed again. If these warm air masses meet obstacles such as mountains or even a cold front, they slide up and very heavy precipitation can occur. Humid air masses from the Mediterranean, for example, were also a major cause of most of the repeated floods on the Oder, Elbe, and Danube rivers, as well as in western Germany in 2021.

Since June 2023, each subsequent month has been the warmest ever observed globally. With the onset of El Niño, which is leading to above-average surface temperatures in the southern Pacific, there is a risk that we will see further extremes next year as well, and perhaps global warming will exceed 1.5°C for the first time.

This makes it all the more important that we slow down further climate change, and equally important that we adapt to the existing one."