The hydrosphere is the sum of all water on a planet, including water on the surface, underground, and in the air. It is a closed system in which water exists and has been around for about 4 billion years, although it continues to change in shape. The hydrosphere is intricate, complex, interdependent, all-pervading, stable, and "seems purpose-built for regulating life". The hydrosphere is essential for sustaining life on Earth and helps connect the Earths systems.
Key facts about the hydrosphere include:
-
Water cycle: The hydrosphere is associated with water in the liquid state, which covers about 70% of the Earths surface. Most liquid water is found in the oceans. Water in a gas state (water vapor) is probably best considered as a feature of the Atmosphere. Additionally, frozen water in the forms of snow, sea ice, icebergs, ice sheets, and glaciers are identified as part of a separate sphere of the Earth System, the Cryosphere. Precipitation, evaporation, freezing and melting, and condensation are all part of the hydrological cycle, a never-ending global process of water circulation from clouds to land, to the ocean, and back to the clouds.
-
Water distribution: About 1.4 billion cubic km of water in liquid and frozen form make up the oceans, lakes, streams, glaciers, and groundwaters found on Earth. Most of the hydrosphere is saltwater, around 97 percent, but the 3 percent that is fresh is critical for terrestrial and freshwater species.
-
Human impact: Humans impact the hydrosphere in various ways, including pollution, abuse, and misuse. Eutrophication, acid rain, and ocean acidification are some of the ways humans impact the hydrosphere. However, humans also rely on the health of the hydrosphere for water supply, navigation, fishing, agriculture, energy, and recreation.
In summary, the hydrosphere is the total amount of water on a planet, including water on the surface, underground, and in the air. It is essential for sustaining life on Earth and helps connect the Earths systems. The hydrosphere is impacted by human activities, but it is also relied upon for various purposes.
