Changed and trends in hydro-meterological variables across Afghanistan - Combining global datasets and local observations

Afghanistan is among the countries most affected by climate change and related hazards. Its turbulent political climate has led to large gaps in meteorological records and low station density limiting research and with little research being done on climate change on a country wide scale. This thesis aimed to investigate the changes in temperature and precipitation based on ERA5-Land reanalysis using existing station observations as a validation measure and how the changes impact the population. Trend analysis was done using Theil-Sen and Mann-Kendell tests on temperature and precipitation data from 1950 until 2021 while extremes were estimated using the proxy of warm days and warm nights (TX90p, TN90p). ERA5-Land showed good representation of station observations, limited by how the precipitation variable is presented within ERA5-Land and comparison between gridded data and station observations. Trend analysis reveal a significant warming greater than 0.02 degrees Celius per year for most of the country, with majority of the warming happening in the rain season and consistent significant temperature increase during the summer. Further, precipitation changes showed drying trends in the low-lying areas while Hindukush mountains saw a wetting trend. The eastern border against Pakistan saw significant increase in precipitation due to the influence of the Indian Summer Monsoon (ISM), which further impacts the larger region encompassing the entirety of South-West and South Asia. Analysis of the proxy extremes shows a large increase in the number of both warm days and warm nights against the reference period 1961-1990. The increase in temperature and reduction in precipitation cause adverse conditions for agriculture and population in general population. Further research into the impacts of climate change in addition creating a lasting station network with regular observations needs to be prioritized.