JenKAS – The Jena Climate Adaptation Strategy

Background and Goals

The city of Jena has around 105,000 inhabitants and functions as a major local centre. Since 2000, Jena has recorded a slight but consistent rise in population. However, the current forecast for Jena predicts a slight fall in population by 2025.

The urban climate is shaped by the location in a valley, surrounded by predominantly steep slopes. This location prevents extensive ventilation and therefore, in low-exchange weather conditions, promotes inversions and, in sunny summer conditions, overheating of the urban area. At the same time, the valley location intensifies the prevailing continental dryness, which means that Jena is among the warmest and driest cities in Eastern Germany.

In terms of the impact of climate change, this results in a very specific effect. Particularly when combined with the valley location, increasingly significant summer overheating and inversions are expected. Because of dry and hot periods, there are increasingly problems of heat islands and an increased risk of forest fires or water shortages for agriculture in the surrounding area. There is likely to be a raised risk of extreme precipitation events bringing about more frequent flooding, particularly in the narrow and steep side valleys.

"JenKAS - Jena Climate Adaptation Strategy" is the name given to a concept drawn up as part of the model project to help the city of Jena adapt to climate effects. It extends the municipal targets for energy and climate protection by incorporating climate adaptation considerations, and takes account of all climate-related fields of urban planning activity in the city.


  •  Incorporation of the impact of climate change into urban development processes with an integrated approach;
  •  Formulation of a targeted local strategy for adaptation to climate change;
  •  Improvement of databases for dealing with climate change;
  •  Raising public awareness;
  •  Making climate change information and data available to local players through an information, cooperation and management system.

To achieve these project objectives, the following steps have been taken:

  •  Analysis of measurement and modelling data and documentation in a local climate change report,
  •  Assessment and documentation of local impact of climate change in the individual areas of activity,
  •  Development of specific spatial adaptation measures,
  •  Creation of cooperative networks for specific players through workshops and Internet-based information portals, and
  •  Publicity work based on events, workshops, presentations and publications.

Content time


Research area/region

  • Germany
Region of implementation (all German federal states)
  • Thuringia
Spatial resolution 


Steps in the process of adaptation to climate change

Step 1: Understand and describe climate change

Approach and results 

The German Meteorological Office (DWD, Senior federal authority in the MBVBS) is providing the required climate data for all Urban Climate projects as a basis for climate effect estimates: Local climatic modelling was carried out using the KLAM_21 cold air model and the MUKLIMO_3 urban climate model.

Parameter (climate signals)
  • Heat waves
  • Altered rainfall patterns
  • Higher average temperatures
  • Sea level rise und storm surges
  • Dry periods

Step 2a: Identify and assess risks - climate effects and impact

Approach and results 

Intensification of the overheating typical for cities, particularly during the increasing periods of summer heat, risk to plant water supply due to increased dryness in summer, more frequent occurrence of sultry conditions, increase in base runoffs due to higher winter precipitation in Saale and tributaries, reduction due to lower precipitation in summer, likely increase in heavy precipitation events in summer, leading to more extreme peak runoffs.

Step 3: Develop and compare measures

Measures and/or strategies 
  • Use of less radiation-absorbing road, square and building surfaces;
  •  Maintenance of cold and fresh air corridors;
  •  Protection against summer overheating in particularly at-risk districts and in the transport and infrastructure sectors;
  •  Protection measures against extreme weather events (storms, heavy rain etc.);
  •  Unsealing and increase in green spaces in heavily paved areas;
Time horizon
  • 2071–2100 (far future)


Funding / Financing 

Ministry of Transport, Construction and Urban Development (BMVBS) and Federal Institute of Construction, Urban and Spatial Research (BBSR): KlimaExWoSt - StadtKlima

Project management 

City of Jena;
Research assistance: Thuringian Institute for Sustainability and Climate Protection (Think)


Regional Planning Association Ostthüringen, Thuringian Ministry of Agriculture, Forestry, Environment and Conservation, Thuringian State Institute for Environment and Geology, German Weather Service (DWD), Helmholtz Centre for Environmental Research (UFZ)


Stadtverwaltung Jena
Am Anger 26
07743 Jena

Printer-friendly version
Fields of action:
 agriculture  buildings  human health and care  spatial planning, urban and settlement development  transport and transport infrastructure  water regime and water management  woodland and forestry