Quantifying the stochastic trends of climate extremes over Yemen: a comprehensive assessment using ERA5 data

Climate change is worsening existing vulnerabilities in developing countries such as Yemen. This study examined the spatial distribution trends of extreme climate indices defined by ETCCDI (Expert Team on Climate Change Detection and Indices), for precipitation and temperature, from 1988 to 2021. It employed both the classical Mann-Kendall (MK) test as well as its modified (MMK) version that accounts for long-term persistence in hydroclimatic time series, that could otherwise impact the significance of the identified trends. It represents the first country-level investigation of climate extremes in Yemen using ERA5 reanalysis data to overcome the limitations of station data. Results found widespread increases in temperature indices, indicating significant warming nationwide. Minimum temperatures amplified more than maximums, particularly TNn (the minimum of the minimum temperature), with an increasing trend of more than 0.7degree celsius per decade. Inland cities exhibited more substantial warming than coastal cities. Precipitation trends displayed higher spatial variability, with intensity indices declining across most areas, raising drought concerns. However, Socotra Island presents an exception, with increased precipitation intensity and heightened flood risks. Furthermore, spatial heterogeneity in precipitation indices underscored Yemen's complex terrain. Fewer trends were significant when applying the MMK test versus MK, confirming the impact of climate variability over the region. This research identifies the most climate-vulnerable regions to prioritise focused adaptation actions. Adaptation strategies are urgently needed, including efficient irrigation, flood assessments for Socotra Island, and investigation of projected climate changes and their implications under diverse topographic and climatic influences.