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Most water in Earth's atmosphere and crust comes from saline seawater, while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Earth is saline or salt water, with an average salinity of 35‰ (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land.
Most of Earth's surface is ocean water: 70.8% or 361 million km 2 (139 million sq mi). [96] This vast pool of salty water is often called the world ocean, [97] [98] and makes Earth with its dynamic hydrosphere a water world [99] [100] or ocean world. [101] [102] Indeed, in Earth's early history the ocean may have covered Earth completely. [103]
Water can be polluted, abused, and misused but it is neither created nor destroyed, it only migrates. There is no evidence that water vapor escapes into space." [12]: 26 Every year the turnover of water on Earth involves 577,000 km 3 of water. This is water that evaporates from the oceanic surface (502,800 km 3) and from land (74,200 km 3).
The entire ocean, containing 97% of Earth's water, spans 70.8% of Earth's surface, [8] making it Earth's global ocean or world ocean. [ 23 ] [ 25 ] This makes Earth, along with its vibrant hydrosphere a "water world" [ 43 ] [ 44 ] or " ocean world ", [ 45 ] [ 46 ] particularly in Earth's early history when the ocean is thought to have possibly ...
When Earth formed around 4.6 billion years ago, some water likely existed in that gas and dust — though much of it would have been vaporized by the sun’s intense heat. (NASA/AFP via Getty Images)
The Earth's crust is one "reservoir" for measurements of abundance. A reservoir is any large body to be studied as unit, like the ocean, atmosphere, mantle or crust. Different reservoirs may have different relative amounts of each element due to different chemical or mechanical processes involved in the creation of the reservoir.
Earth's approximate water volume (the total water supply of the world) is 1.386 billion cubic kilometres (333 million cubic miles). [24] Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, pond, or puddle. The majority of water on Earth is seawater. Water is also present in the atmosphere in solid ...
The water crisis threatens more than 50% of global food production and risks shaving an average of 8% off countries’ GDPs by 2050, with much higher losses of up to 15% projected in low-income ...