<p>This edited book is based on selected papers at the 3rd MedGU Annual Meeting, Istanbul 2023. It spans a large spectrum of atmospheric, ecological, and hydrological topics, and presents newest observations, simulations, analyses and predictions mainly relevant to circum-Mediterranean Regions. This book shares new insights into dynamical evolutions of atmospheric, ecological, and hydrological processes and improved practices in sustainable environment management. It will be of interest to scientists, engineers, practitioners, and policymakers in the field of climatology, oceanography, ecology, biogeochemistry, hydrology, hydrogeology, and geosciences in general. Meanwhile, this book is also of great value to students and environment-related professionals for further investigations on the state of Earth systems.</p>