Trends and amount changes of temperature and precipitation under future projections in high-low groups and intra-period for the Eastern Black Sea, the Wettest Basin in Türkiye

Abstract

This study investigates the possible efects of climate change on temperature and precipitation variables in the Eastern Black Sea Basin, Türkiye’s wettest and food-prone region. The outputs of three GCMs under historical, RCP4.5, and RCP8.5 scenarios were downscaled to regional scale using the multivariate adaptive regression splines method. The future monthly temperature and precipitation for 12 stations in the basin were projected for three periods: the 2030s (2021–2050), 2060s (2051–2080), and 2090s (2081–2100). In addition to relative changes, high and low groups and intra-period trends were analyzed for the frst time using innovative methods. For the pessimistic scenario, an increase of 3.5 °C in the interior and 3.0 °C in the coastal areas of the basin is projected. For the optimistic scenario, these values are expected to be 2.5 and 2.0 °C, respectively. A decrease in precipitation is projected for the interior region, and a signifcant increase is expected for the eastern and coastal areas of the basin, especially in spring. This result indicates that foods will occur frequently coastal areas of the basin in the coming periods. Also, although the monotonic trends of temperatures during periods are higher than precipitation in interior regions, these regions may have more uncertainty as their trends are in diferent directions of low and high groups of diferent scenarios and GCMs and contribute to all trends, especially precipitation.