Exploring Future Bioclimatic Changes In Western Türkiye Under SSP3 Projections

This study investigates climate change patterns in the western region of Türkiye using high-resolution bioclimatic variables to capture the detailed spatial and temporal changes. It is funded by the project titled Predicting the Distribution of Future Basic Forest Tree Species Using Different Climate Projections and Developing Adaptation Strategies for Turkey' which is implemented under the “Climate Change Adaptation Grant Program (CCAGP)”.

The western part of Türkiye is characterized by vast agricultural areas and majority of the nation’s forest stock both of which play critical roles in the country's economy and ecology. The region's agricultural lands serve as one of the primary suppliers of food and resources to urban centers, ensuring food security and economic stability. Additionally, the forests in this area are ecological hotspots, hosting approximately 300 endemic plant species and contributing to biodiversity conservation. The importance of agriculture and forestry in the region emphasize the need for a thorough understanding of climate impacts, facilitating the development of sustainable agricultural and forestry management practices and policies to protect these vital resources.

To explore these dynamics in depth, we conducted the regional climate model simulations using COSMO-CLM at a convective permitting resolution 2.5 km x 2.5 km, driven by the EC-EARTH3-Veg from the CMIP6. These simulations were carried out for both historical (1995-2014) and future periods, including the mid-century (2050-2059) and the end of the century (2090-2099) under SSP3-7.0 scenario. To assess the reliability of the regional climate model, we compared its output with observational data from the region for the reference period. Key variables such as temperature and precipitation were analyzed, and their values were contrasted against the on-site measurements. Subsequently, we calculated bioclimatic variables for the reference period, as well as for the mid-century and end-of-century projections, to assess how these climatic changes might affect the region over time.

This high-resolution analysis enables a detailed assessment of 19 bioclimatic variables and their trends throughout the century how the agricultural and forest areas respond to climate change. Acquiring knowledge of the projected increase in temperature and the decline in precipitation by the end of the century is crucial for understanding the impacts on these vital areas, which are essential for ecosystem health and biodiversity. Under the SSP3-7.0 scenario, our findings indicate that annual mean temperatures increase around 4.5°C when comparing the period of 1995-2014 with that of 2090-2099. Also, we found that annual precipitation amount over the region decreases around 170 mm/year, which indicates a nearly 25% reduction in the freshwater availability by the end of the century. Especially, the precipitation of the wettest month shows a comparable decrease across these periods. Understanding these shifting in bioclimatic variables is crucial to preserve the agricultural and forest areas with their biodiversity.