Planet Earth in the solar system is called the “Blue planet” because of the vast oceans that cover 2/3 of the surface. Water and the atmospheric envelope surrounding the Earth are the most important factors supporting biological life. The surface of the Earth is covered by 71% with water, but, only 3% of this water on the Earth’s surface is freshwater and less than 0.5% of the fresh water is accessible for consumption as drinking water. The Hydrologic Water Cycle on Earth influences the intensity of climate variability and climate changes on Earth throughout the year and plays important part of extreme events such as cyclones, droughts and floods. The history of Earth has many examples that well established civilizations collapsed and disappeared from lack of water and especially from extensive droughts that affected agriculture and water resources. The irony is, that today more than one billion people do not have access to safe drinking water and it is estimated that by 2025, almost 20% of the global population are likely to be living in countries or regions with absolute water scarcity. Global estimates showed that 1.3 billion jobs worldwide (42% of the world’s total active workforce) are heavily water-dependent, including work in agriculture, mining and industries ranging from paper to pharmaceuticals. Global water scarcity is the result of overpopulation, urbanization of more than 50% of the global population which increased consumption, intensive agriculture wasting large volumes of water, expansion of the industrial and energy sectors that need vast amounts of water are some of the causes for future water scarcity on Earth. But the most important factors are climatic change and increasing surface temperatures. This review collected some important research papers, books and reports from national and international organizations and the IPCC (Intergovernmental Panel on Climate Change) which have advanced the investigations for the scientific basis of the climate changes of the last decades and the threat of rising temperatures on Earth ecosystems, urban and coastal areas, agriculture and fresh water resources.