Though generally recognized as several separate oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. More than half of this area is over 3,000 meters (9,800В ft) deep. Approximately 71% of the surface of the Earth (an area of some 362 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. If, for instance, in an agricultural field, the mineralogic composition and the structure of its soil are similar to those of an undisturbed forest soil, but the structure is quite different.ДЄn ocean is a major body of saline water, and a component of the hydrosphere.

More precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform. The massive environmental changes of humanity in the Anthropocene have fundamentally effected all natural environments: including from climate change, biodiversity loss and pollution from plastic and other chemicals in the air and water. People cannot find absolutely natural environments on Earth, and naturalness usually varies in a continuum, from 100% natural in one extreme to 0% natural in the other. Though many animals build things to provide a better environment for themselves, they are not human, hence beaver dams, and the works of mound-building termites, are thought of as natural. Even acts which seem less extreme, such as building a mud hut or a photovoltaic system in the desert, the modified environment becomes an artificial one. Built environments are where humans have fundamentally transformed landscapes such as urban settings and agricultural land conversion, the natural environment is greatly changed into a simplified human environment. In contrast to the natural environment is the built environment. Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation, electric charge, and magnetism, not originating from civilized human actions.Complete ecological units that function as natural systems without massive civilized human intervention, including all vegetation, microorganisms, soil, rocks, atmosphere, and natural phenomena that occur within their boundaries and their nature.The concept of the natural environment can be distinguished as components: This environment encompasses the interaction of all living species, climate, weather and natural resources that affect human survival and economic activity. The term is most often applied to the Earth or some parts of Earth. The natural environment or natural world encompasses all living and non-living things occurring naturally, meaning in this case not artificial. It is the world's largest hot desert and third-largest desert after the polar deserts.

An image of the Sahara desert from satellite.

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