Exploring the impacts of climate change on extreme climate indices in Türkiye: Insights from statistically downscaled CMIP6 models

Date

2023-9-06

Author

Gümüş, Berkin

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This study utilizes the most recent versions of all available global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). These models are employed to assess climate extremes in Türkiye for the period 2015-2100, using two future scenarios of Shared Socio-Economic Pathways, SSP2-4.5 and SSP5-8.5. This study is a first in terms of using high resolution CMIP6, scenario and model diversity, and examining the entire projection period over Türkiye. Three types of quantile mapping techniques, namely quantile mapping, detrended quantile mapping, and quantile delta mapping, are employed to downscale coarse-resolution climate models to a spatial resolution of approximately 9 km (0.1° × 0.1°). This downscaling process was carried out using the European Centre for Medium-Range Weather Forecasts Reanalysis 5-Land (ERA5-Land) dataset as the reference data. The analysis of the 12 extreme precipitation indices (EPIs) and 12 extreme temperature indices (ETIs) between the years 2015 and 2100 consistently indicates an increased frequency and intensity of extreme weather events in Türkiye, as projected by the two future scenarios. According to the SSP5-8.5 scenario, there is a higher degree of water stress compared to the SSP2-4.5 scenario, where in the Aegean and Mediterranean regions of Türkiye, reduction in total precipitation reaches 20%. Although the overall amount of precipitation may decrease, the results suggest that the severity and frequency of extreme precipitation events are on the rise. This implies that a greater proportion of the total precipitation will be contributed by these extreme events. It is also anticipated that there will be an increase in temperature extremes, including both the lowest and highest daily maximum temperatures, throughout all parts of Türkiye. This trend signifies a warming signal of up to 7.5 °C by the end of the current century. Particularly in the southern regions, these elevated temperatures pose a serious threat to public health. Cold extremes also exhibit a tendency towards warming, as seen by the significant decrease in the number of ice days across all areas. This trend may potentially result in less snow accumulation, which might negatively affect several sectors.

Subject Keywords

Climate Change, CMIP6, Statistical Downscaling, Quantile Mapping

URI

https://hdl.handle.net/11511/105612

Collections

Graduate School of Natural and Applied Sciences, Thesis