Earth Science and Engineering Ph.D. Dissertation

Abstract

Saudi Arabia is one of the warmest places on Earth with record summer temperatures reaching 50 °C and above. Lack of rain makes the climate harsh, and puts the survival of over 30 million of Saudi Arabia's inhabitants at risk without continuous access to energy-intensive cooling and desalinated water. As the regional climate continues to warm, the already challenging conditions will only worsen. In this thesis, we looked at the historic climate change in Saudi Arabia and its consensuses for human health and vital sectors of the economy: electricity and water. We analyzed the long-term trends in temperature and temperature extremes over the period of 1950-2021, relying on the latest high-resolution ERA5 reanalysis. Previous studies used low-quality data over limited time intervals, with reported results inconsistent among the authors and the recent years' data absent. Moreover, regional research has a focus on temperature-only effects of warming. However, dry bulb temperature alone is not an adequate metric to study the change in heat stress in humid environments. Humidity is an important contributing factor, especially for the Arabian Peninsula's coastal regions. Our findings indicate that since the late 1970s, Saudi Arabia has warmed up at a rate that is 50% higher than the rest of the land mass in the Northern Hemisphere with summer temperatures rising faster than average annual temperatures, and with minimum temperature increase surpassing the rise in maximum values. The humidity-related heat stress has soared with heat index change reaching 4 °C and above in many locations during the past four decades. Climate change effects along with the fast-growing population will exacerbate the high demand for electricity and water. Each 1 °C temperature increase is associated with a 4.5% rise in power generation in the Central region, and a 5.4% increase in the more humid coastal Western region. Rain occurs rarely in the Kingdom, and the impact of climate change on natural water supply is insignificant. However, further temperature increases will escalate the demand for freshwater due to increased evapotranspiration of crops and irrigated vegetation in cities. Given these challenges, careful resource management is essential. To understand the efficiency of freshwater use, we developed a novel methodology that allowed us to estimate the country-scale efficiency of agricultural water use. Water requirements for crop cultivation in Saudi Arabia are up to three times the global average.