Final answer:
Water is essential for life as it composes a major percentage of the human body and is crucial for physiological functions. Earth is uniquely abundant with liquid water, but less than 1% is fresh and drinkable. The preservation and management of this finite resource are increasingly important as human demands grow.
Step-by-step explanation:
Water is indeed considered Earth's essential resource for several compelling reasons. It is central to nearly all life processes, as humans and many other living organisms have bodies composed majorly of water, with human adults at about 60% water and our brains being about 85%. This vital fluid not only constitutes a large part of our physical makeup but is also crucial for our physiological functions, including the regulation of body temperature, transport of nutrients, and elimination of waste.
Moreover, water plays a fundamental role in the environment. It is involved in the process of photosynthesis, which is how plants convert light into oxygen, thereby maintaining the balance of oxygen and carbon dioxide in the atmosphere. The Earth, known as the Water Planet, is unique in the solar system for its abundance of liquid water, covering approximately 70% of the surface. Although a vast quantity of water is present, less than 1% is available as fresh, drinkable water, since most of it is contained in oceans as saltwater or trapped in glaciers and ice caps.