Simulating expected climate change in the Jordan River region using Regional Climate Models (Briefing 1.3)

Abstract

The Jordan River basin is located within the Mediterranean climate zone. In this water scarce environment, the availability of sufficient amounts of water is critical for development and, potentially, a source of regional conflicts. According to the latest report from the International Panel on Climate Change (IPCC), released in 2007, semiarid regions such as the Mediterranean are likely to experience a decrease in water resources due to climate change. This IPCC statement is based on data obtained from several Global Climate Models (GCM) and different emission scenarios. In order to investigate the impacts of climate change for the Jordan River region in detail, the resolutions of these GCMs are too coarse. Since the region is characterized by sharp gradients of main climate variables, especially rainfall, much higher spatial resolutions are required. These are obtained from Regional Climate Models (RCM) that dynamically downscale the coarse information of the GCM considering local topography, highly resolved land use and soil properties as well as more suitable model parameterizations. Trend analysis showed a statistically significant increase in temperatures of 1°C over the past 50 years. Until the year 2060, mean annual temperatures are expected to increase by 2°C with an increase in warm spell length. Furthermore, a decrease of 10% in mean annual precipitation with increased frequency of strong precipitation events is expected for large parts of the Jordan River region until 2060. Addictionally, a decrease in precipitation is expected to continue with higher levels of significance until the year 2100.