A 'regime shift' is happening in the Arctic Ocean, scientists say

Scientists at Stanford University have discovered a surprising shift in the Arctic Ocean. Exploding blooms of phytoplankton, the tiny algae at the base of a food web topped by whales and polar bears, have drastically altered ...

First direct evidence of ocean mixing across the Gulf Stream

New research provides the first direct evidence for the Gulf Stream blender effect, identifying a new mechanism of mixing water across the swift-moving current. The results have important implications for weather, climate ...

Behind the dead-water phenomenon

What makes ships mysteriously slow down or even stop as they travel, even though their engines are working properly? This was first observed in 1893 and was described experimentally in 1904 without all the secrets of this ...

Texas will face driest conditions of the last 1,000 years

Texas' future climate will feature drier summers and decreasing water supplies for much of the state for the remainder of the 21st century—likely resulting in the driest conditions the state has endured in the last 1,000 ...

Liquid water is more than just hydrogen-oxygen molecules

Skoltech scientists in collaboration with researchers from the University of Stuttgart showed that the concentration of short-lived ions (H3O+ and OH-) in pure liquid water is much higher than that assumed to evaluate the ...

Arctic Ocean changes driven by sub-Arctic seas

New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm.

Venice completes first test of all flood barriers

Venice's long awaited flood defence system designed to protect the lagoon city from damaging waters during high tides on Friday survived a first test of its 78 barriers.

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Water is a ubiquitous chemical substance, composed of hydrogen and oxygen, that is essential for the survival of many known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.

Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.

Clean, fresh drinking water is essential to human and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.

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