BLUE WONDER
THE EARTH'S WATER FACTS
There is an amazing quantity of H2O in the universe. However, Earth is the only "blue planet" in our solar system and therefore the only oasis in the otherwise hostile universe. Those who want to understand the dimensions of the huge volume of water on Earth need to cast an eye on the blue wonder, dissolved into facts and figures.
IN SURFACE ABUNDANCE
When, 4.5 billion years ago, the Earth was born as a ball of fire, the molecules in its primordial soup began to arrange themselves only very slowly: Heavy and hot molecules drifted towards the Earth's core, light and cold ones - like hydrogen and oxygen - towards the surface. They did this until a cooling rain storm started lasting millions of years. No-one knows exactly when and how the first oceans and creatures developed from this mega-deluge. Although the world's seas principally form a phenomenal sloshing surface of water on the Earth, us humans deliberately separate them from each other on our maps with our considerably smaller, unrelated land masses. Perhaps to cleanse ourselves of the idea that we erroneously named our planet "Earth" and not "Water".
Percentage of the Earth's surface covered with water
71
Earth's estimated total volume of water in billion km³
1,4 bis 1,6
The length of the side of a cube which could hold the Earth's estimated total volume of water in km
1150
Water in different states as a percentage of the total volume of water
98.233 (liquid water), 1.766 (ice, snow), 0.001 (water vapour)
SWEET AND SALTY TRUTHS
In his book, "Life's Matrix: A Biography of Water", author Philip Ball quotes the sailor's saying: "Water, water, everywhere, nor any drop to drink." This statement illustrates what must have gone through the minds of countless shipwreck victims as they slowly died of thirst in the middle of the sea, surrounded by salt water. the process of osmosis in the human body is responsible for this. When the walls of our cells are surrounded by salt water on the outside, our bodies try to equalise this imbalance by releasing the "useful" fluid inside the cells, which contains many times less salt, through the membranes. With every gulp of seawater, we extract, so to speak, the remaining fluid from our cells - and thus become even more parched. Neither are our kidneys designed to process an overdose of salt from seawater, and even at an early stage, this leads to fatigue, muscle cramps and swelling of parts of the body.
(However, there are intrepid adventurers who claim the opposite, who tell all proponents of freshwater that humans can live like a fish in the ocean. One of these is the Frenchman Alain Bombard, who, in 1952, drifted from Gran Canaria to the Caribbean for 65 days in a dinghy in a thirsty self-experiment and claims to have nourished himself in this time exclusively by drinking seawater. A few years later, another survival hero, the German doctor Hannes Lindemann, did not do quite as well and only made it to his destination alive thanks to rainwater. He documented his results in a book, "Alone at Sea", which is considered the standard reference for maritime survival training today. In it, the author instantly lays bare his relentless predecessor's deceit: Bombard is said to have loaded litres of drinking water and food before he left, which he never mentioned, but which was obviously seen.
Whether Bombard was telling the truth or not,) the salty survival trick seems to lie in a clever balance between the helpful and the damaging: A body which is not yet completely dehydrated is evidently in a position, for a certain period of time, to thin the saltwater, which can lead to fluid being taken on by osmosis, if only a little. When facing great thirst, the fluid stored in the cells together with small doses of seawater apparently helps to keep the organism alive for a while. On the other hand, if you start drinking when you are already dehydrated, the high concentration of salt can no longer be lowered. (A shipwreck-survivor called Kurt Kunz, whose trimaran capsized in a mistral storm in 1982 between Corsica and Minorca, saved himself and the rest of his crew on a small island off the coast of Algeria. The three survived there for eight days by drinking four gulps of seawater in the morning, at midday, and in the evening. Without this diet of saltwater they would have died of thirst within only a few days.) The academic question behind this cannot be definitively settled however: When does the direction of osmosis in the body switch over? At what point can we no longer drink saltwater, when its salt concentration is damaging to our health or even life threatening? It seems the only thing we know for sure is that a person who drinks seawater can survive for a few days or even weeks longer than someone who drinks nothing at all.
It is no secret that our planet is not free from aridity and drought. If we consider the proportion of saltwater to freshwater on the Earth, it could hardly be more disadvantageous. Even the tiny amount of existing freshwater is not necessarily drinking water or useable, especially as it is - as unequally as it is distributed over the globe - largely frozen in ice sheets and glaciers. We are lucky that in water we have a resource which, although it is extremely scarce, is renewable, which continually replenishes itself in a constant water cycle of evaporation, precipitation, infiltration and circulation.
Volume of saltwater in the total volume of water in billion km³
Approx. 1.36
Volume of freshwater in the total volume of water in billion km³
Approx. 0.04
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Freshwater as a percentage of the total volume of water
max. 2.8
Drinking water as a percentage of the total volume of water
1
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Percentage of salt in seawater
3
Percentage of salt in human cell fluid
approx. 0.9
Percentage of salt that human kidneys can excrete
2
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Fixed, inaccessible freshwater (in glaciers, snow, polar ice caps and within the Earth) as a percentage of total freshwater
75
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Volume of freshwater in groundwater in km³
8,000,000
Volume of freshwater in lakes and rivers in km³
190,000 - 225,000
Volume of freshwater in the atmosphere in km³
13,000
Volume of freshwater in the atmosphere in km³
16,500
Volume of freshwater in all living creatures in km³
1,100
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Daily precipitation on land in km³
approx. 330
Daily evaporation of water on land in km³
approx. 220
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Daily precipitation on the seas and polar ice
in km³
1,040
Daily evaporation of seawater in km³
110
LIVE AND LET DIE
Freshwater gives (human) life, saltwater destroys it. This is how we could express, in a strongly simplified way, the crux of the liquid's contradictions. Admittedly, the salty oceans provide us with important waterways, but at the same time they also give us the dangers of currents, climatic fluctuations, storms, earthquakes and tsunamis.
"It was not saltwater, but freshwater that surrounded and nourished the roots of human culture," as Philip Ball describes the virtues of the more insipid of the two substances. The four oldest great cultures of the Earth sprung up on major rivers like the Tigris, Nile and Indus: Mesopotamia (in present-day Iraq), the Harappan culture (in present-day Pakistan), China and Egypt. Freshwater is thus the origin of every civilisation, at least in those places where it is sufficient, clean and potable. Yet water is much more than that. It is "the matrix of our life", as GEO author Klaus Bachmann writes. After all, we are beings who are partly made of the liquid. They say it is like jelly in our cells, seasoned with proteins, salts, amino acids, sugars, fat and genes. Thus man is simply hydrophilic in every way: a water-loving microcosm from the outside and inside.
Percentage of the global population dependent on water from mountainous regions / glacial terrain
More than 50
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Percentage of tap water provision in large cities world wide
94
Percentage of households world wide with a sewage disposal system
86
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Volume of drinking water needed to cover a person's daily requirement in l
20-50
Average daily water balance (both intake and release) in an adult human body in l
2.4
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Percentage of water in the human body
65-75
WPercentage of water in the human brain
77
Percentage of water in the human muscle tissue
80
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Number of days humans can survive without water
5-7
The longest reported time a person has survived by only drinking saltwater in days
65
GEOGRAPHY OF THE SUPERLATIVE
The geography of water is also a history of the superlative. Since time began, the Earth's natural liquid spectacles have highlighted our own diminutiveness. When we look at a huge waterfall or the infinite horizon above the ocean we are also fascinated because these forces of nature defy all human control. How many explorers and adventurers have lost their lives because they were not equal to the power of the object of their own exploration? David Livingstone died in 1873 looking for the source of the Nile, after having already found that of the Congo in 1866. The American Jimmy Angel discovered Angel Falls in 1936 with his sporting aeroplane and landed on a plateau, from which he could not start the plane again, owing to its soft surface. (Mariners died as a direct consequence of the water, in storms or from drowning, or indirectly of yellow fever, dysentery and scurvy.
In the face of all this adversity, the dangers of the waters do not appear to lessen our wanderlust in any way. The wife of James Cook, the last great maritime explorer, spent only four full years with her husband of 14 years of married life. Cook never settled down, his life was a constant expedition, eternally striving to solve the mysteries of the seas. Tellingly, the captain named his ship "Endeavour", on which he discovered the Northwest Passage and numerous Pacific islands, among other things. At the age of 48, the South Pacific became his final resting place. Cook's wife died in 1835, 56 land-bound years after her husband.)
Largest ocean
Pacific (180 million km²)
The three major oceans
Pacific, Atlantic, Indian Ocean
Number of seas
Approx. 50
Deepest measured point in an ocean in m
11,034 (Mariana Trench, Pacific)
Average depth of the world's seas in m
3,730
Largest ocean current
Antarctic Circumpolar Current
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Largest iceberg
Unnamed, Antarctica
(31,000 km², about the size of Belgium)
Highest iceberg
Unnamed, Greenland
(167 m)
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Longest river
Nile, Africa
(6,671 km from Lake Victoria in Eastern Central Africa to its mouth at the Mediterranean Sea)
River with the largest drainage basin
Amazon, South America
(6,145,186 km²)
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The three largest bodies of saltwater
Caspian Sea (400,000 km²), Great Salt Lake (4,400 km²), Dead Sea (600 km²)
Largest freshwater lake
Lake Superior, United States and Canada
(82,000 km²; 563 km long and 257 km wide)
Country with the most freshwater lakes
Canada
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Largest volcanic crater lake
Lake Toba, Indonesia
(4,000 km)
Oldest and deepest lake
Lake Baikal, South East Siberia
(25 millions years old, 1,700 m)
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World's highest waterfall
Angel Falls, Venezuela
(approx. 1,000 m, called "Churun Meru" - vertical river - by the natives)
Largest volume of water that falls per second in a waterfall in m³
17,000 (Boyoma Falls, Congo, 60 m)
World's largest water cascades
Yosemite Falls, California
(740 m, 3 stages)
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Longest navigable waterway for seagoing vessels
St. Lawrence Seaway, Canada
(3,700 km)
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The three largest wetlands which are rainwater stores (moorland, peatland, marshes, flat bodies of seawater)
West Siberian Plain (780,000 - 1,000,000 km²); Amazonian wetlands (800,000 km²); Hudson Bay lowlands (200,000 - 320,000 km²)
The rainiest place on the Earth (with only 15 dry days per year)
Mt. Waialeale, Kauai, Hawaii
