On October 13 and 14, 2021, the climXtreme Midterm Meeting took place as another virtual event…
Among project members, steering group, members of the DLR-Projektträger (PT), members of the Scientific Advisory Board (SAB) and members of the initiative “Contact to Climate Research” (Begleitgruppe), about 100 people participated in the meeting. The Midterm Meeting consisted of overview talks, poster sessions, presentation of the first publications, talks on the progress of the topic-specific meetings and a discussion session on the July 2021 extreme flood event and the role of ClimXtreme in the occurrence of future events. The aim of the ClimXtreme project is to provide sound answers to the two following questions:
- Has past climate change caused more extreme events?
- Will future climate change modify the occurrence of extremes?
At this point many sub-projects were able to provide first statements to these questions.
Heatwaves:
- They are becoming more frequent.
- There has been an increase in the intensity of European heatwaves since approximately the last 20 years.
- There was an increase in the tropical nights in the past.
- The wet-bulb temperature crosses critical values of 32°C and 35°C by 2050 in scenarios RCP2.6 and RCP8.5 in Germany, France and Spain.
- The number of fatalities by heatwaves under RCP8.5 could be twice the rate as under RCP2.6.
Extreme precipitation:
- The climate change increased intensity and likelihood of extremes similar to the July 2021 event in the past. Such events will become more frequent and severe in the future.
- Changes in heavy and extreme precipitation events/periods between 1951 and 2100 from regional climate simulations are quantified in respect to different greenhouse gas emission scenarios (Representative Concentration Pathways scenarios). An increase in the frequency and intensity of extreme precipitation is robust and significant over large parts of Europe (Middle Europe, East Europe, Scandinavia, British Islands). Changes are generally stronger in scenario RCP8.5 than in RCP4.5
- Windstorms: There was an increase of intensity of strong extra-tropical cyclones, increase of wind gusts and decrease of cyclone speed in the past.
The joint output of ClimXtreme will be published in an inter-journal special issue of the EGU/Copernicus journals under the title Past and future European atmospheric extreme events under climate change with Natural Hazards and Earth System Sciences (NHESS) as the lead journal. The steering group expects ClimXtreme to submit 30 manuscripts. The discussion session about the flood events in Germany in July 2021 started by three talks given by research groups, which have been involved in the investigation of the recent event in different task forces. A statement about the flood event has been published (in German) on the ClimXtreme webpage.
The main conclusions from this 2-day meeting are:
- The ClimXtreme project is on the right track. First statements on the central questions of the project are already available.
- Although no physical meeting could take place in the period March/2020 to October/2021 due to the Covid19 pandemic, the cooperation partners/groups could be successfully installed on different levels: within modules, cross-modules and also outside ClimXtreme.
- In the light of the July 2021 flood event, it became even clearer that the added value of ClimXtreme is to better understand and communicate the causes and impacts of such events together with the side statement that current (weather forecast) models seem to contain the sensible processes responsible for such an extreme precipitation event due to the fact that the event was forecasted at lead times 2-3 days ahead.
- In order to be able to react faster in case of future extreme weather events, the project will benefit from a coordinated task force.
