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Creato da Vittorio M. Canuto « clicca sul nome per leggere il curriculum dell'autore

Water and Civilization: Past and Future - Vittorio M. Canuto -

Water is a deceptively simple but ultimately intriguing substance with subtleties that still defies us. First, it is formed by two hydrogen and one oxygen atoms. Hydrogen exists in the universe since the beginning, actually almost the very beginning, since the Big Bang’s high initial temperatures did not allow atoms to form until some 10,000 years after the “beginning”.
But compared to the universe’s age of about 15 billion years, the 10,000 years is literally nothing. Thus, to all practical purposes, hydrogen can be viewed as a “primordial” or “cosmic” element.
The same is not true of oxygen that got formed only billions of years later, in the final stages of stellar evolution, when stars die, explode and spew into the interstellar space the products of their labor, oxygen being one of them.
Thus, H2O is the combination of a ”birth” product (hydrogen) and a “death” product (oxygen).
This simple molecule exhibits some remarkable features, the more significant one is that it remains liquid in the temperature range in which life exists.
This is quite unusual if we consider other compounds found in planets, for example CH4 (methane), NH3 (ammonia), CO2 (carbon dioxide) etc., that exist in the liquid phase only at far lower temperatures. So important is water to life that an obstinate reductionist could defend the viewpoint that most organisms are just complex bags of water: human are 70% water with the salinity of their bloodstream intriguingly reminiscent of the ocean salinity (3%).
In a more generous interpretation, the large component of “cosmic” hydrogen in our bodies make us more akin to the cosmos than to the solid earth on which we live, the major components of which bear no resemblance to our chemical composition.
With a further spark of intellectual voltage, someone even claimed that we are more like “angels” than “terrestrials”, the history of humans’ actions to the contrary notwithstanding.
A further important characteristic of water is that its solid phase (ice) is less dense than its liquid phase.
Ice, as we know, floats on water, a somewhat trivial consideration that has, however, important consequences.
If it were the other way around, ice would sink at the bottom of the ocean, it would never melt and in the long run all the earth’s water would freeze solid, a scenario hardly conducive to life.
Where does water come from?
Outer space, essentially a gift from abroad, courtesy of visiting asteroids and comets, dirty snowballs that obstinately crushed on our young earth unleashing ice that was later vented out by volcanoes: that is how our oceans were formed, the staggering volume of which is 1.4 billion cubic kilometers.
Since such a figure is hard to fathom, let me say that if such water were evenly distributed over the earth’s surface, it would form a layer 1.8km high.
 And finally, inside those very oceans is where life begun. The building blocks of life are the amino-acids.
Whether they were brought to earth by successive cometary crushes or built on earth out of a mixture of noxious gases that under external influences (e.g., lightening, radiation, sound, etc) gave rise to more useful amino-acids, is probably a metaphysical anxiety that will never be solved.
But it does not really matter since in the long run we know one thing for certain: amino acids are very fragile (molecular bonds are generally weak) and if exposed to the solar UV radiation, they would have been wiped out. With the original building bricks shattered, life would hardly have emerged.
The only defense was to hide under water, a subterfuge that unconsciously we still practice when at the beach.
Water was literally the cradle of life that hid in it for some four billion years until it was safe to emerge, some 450 hundred million years ago, in the pre-Cambrian when enough oxygen and thus ozone had accumulated in the earth’s atmosphere to screen the damaging UV radiation.
Life has been on solid earth, meaning not under water, for only 10% of the earth’s existence.
Given that these simple facts highlight the tight, often-unappreciated relation of life with water, it is hardly surprising that many civilizations have regarded and many still do, water as sacred, the matrix of life and culture. For example, India, where every river is sacred, derives its name from the great river Indus.
The Ganges is considered the holiest of all rivers (a favor that the mighty river repays quite generously for it contains minerals that kill bacteria!).
The ancient name of the river Thames was Tamesa, a river deity.
In the Bible there are some 200 references to water and Moses means ”Drown from water”. T.S. Eliott had this to say about the Mississippi “I don’t know much about Gods, but I think this river is a strong brown God”.
Christianity tried to erase the spiritual worship of water for it consider it a pagan activity perilously close to idolatry, but people’s deep faith in the sacredness of water won the a battle if not the war, for Christianity included the baptism and the hand ablution in its rituals.
This evidence, though anecdotic, is cited only to underscore the historical discontinuities with the past that recent events have brought about.
The first was the Industrial Revolution (IR) some 200 years ago. With that, humanity crossed an invisible Rubicon and our relation with nature would never be the same. Much as the mythical giant Antaeus who drew strength from contact with his mother Gea, the goddess earth, for thousand of years humankind lived on the earth connected to it.
But Hercules arrived, says the mythology, lifted Antaeus above ground, cut his contact with Earth and weakened him to the point he could crush him.
The IR may represent the unintended present day Hercules for it has disconnected us from earth introducing a discontinuity in our history. With the advent of the IR, all values became synonyms of “commercial values”, thus losing their spiritual, ecological and cultural significance.
Forests are no longer “living communities” but timber factories, mineral are no longer the “veins of the earth” but raw material, rivers and aquifers have become commodities. I believe we are relying on a wrong equation, value=monetary value, an historical distorsion the pernicious consequences of which are beginning to surface with alarming clarity.
As O.Wilde wrote: “We know the price of everything and the value of nothing”.
For millennia, water rights were considered “usufructuary rights”: water could be used but not owned.
Historian D.Worster has noted that the European settlers in the eastern USA rejected the traditional doctrine of “riparianism” based on the concept of water as common property that for millenia guided human settlements the world over. Instead, they chose the doctrine of prior appropriation, Qui prior est in tempore, potior est in jure, the loose translation of which is “might is right”, a self-serving frontier logic, not an example of enlightened altruism.
The political-philosophical underpinning of such a behavior can be traced back to John Locke’s treatise on property in which he effectively legitimized the theft of the commons of Europe.
The second good event with worrisome consequences is the much acclaimed Green Revolution (GR) of the 50’ that literally prevented the occurrence of the Malthusian ghost by avoiding the starvation of ten of millions of people.
A universally credited success story in the global food supply, GR had an hidden cost for it replaced drought resistant local crops with water guzzling crops, transforming water abundant regions into water scarce regions and water scarce regions into famine regions.
The naturally wet territories of South-East Asia is where rice culture evolved because paddy fields irrigation was the natural response to a naturally wet region.
In the same vein, arid regions is where wheat, barley, maiz, etc., grew as staple food. “Los hombres de maiz” of Nobelist Miguel Angel Asturias comes to mind, where maiz is found in the Mayan cosmogony as the primordial element out of which God created man.
An analogously worrisome situation occurs in our treatment of forests with the now infamous but seemingly unstoppable logging.
To all practical purposes, logging is the destruction of ”natural dams”. In fact, forests conserve water in the so-called catchments and release it slowly via streams and springs.
By cutting down forests, we allow water to run off and hamper if not destroy the conservation capacity of soils.
Flooding under heavy rain is just one of the unwelcome consequences. In the context of forests, timber and logging, it must be stressed that the paper and pulp industry is also adversely affecting the water budget. Large eucalyptus plantations are a major source of concern. In South Africa eucalyptus invaded more than 100 million hectares and used 3.3 billion km cube of water.
 When the plantations were finally eradicated along the river banks, the stream flow increased by 120%!
The third event is Globalization, a typhoon that seems to have swept the world but certainly did not unite it. It has its ardent devotees and its fierce detractors, as the facts demonstrate. Suffices it to say that is has shifted the definition of water from that of a “common property” to that of a “commodity” to be bought and sold like any other commodity under the unproven and perhaps dangerously illusory expectation that the hidden hand of the free market, the deus ex machina, will fix all potential glitches along the way.
The change brought about is not an incremental improvement on a time honored practiced used for millennia, it is a further example of an abrupt change of direction oblivious of the fact that historically water had been considered a common property not a private property. What is being suggested is a change from cooperation to competition, an altogether different scenario of ultimately adversarial nature about a substance that is at the basis of the life of every human being. As a witty man said ”in Colorado water flows uphill where the money is”.
The fourth event is Climate Change. We know that over the last 100 years the earth’s surface has warmed of 0.60C. While at first sight this may look like a small increase, it must be stressed that it is an unprecedented warming in the last 1000 years. This goes to emphasize the fact that we should look not only at the warming per se but also at the time it takes to occur.
This is what makes the 0.6 0C increase in only 100 years a unique phenomenon. In addition, recent studies have shown that there has been a warming of the world oceans and that such warming cannot be explained with only atmosphere-ocean interactions. It requires “a sustained, positive thermal forcing such as that expected from a greenhouse effect”.
Other components of the climate system have changed over the last fifty years: the extent of Antarctic sea ice has been reduced of 311km; the volume of mountain glaciers has decreased of 4000 km3 and the volume of perennial Arctic sea ice has decreased by 40% (measurements from nuclear submarines), a set of phenomena consistent with warming on a global scale (Appendix B).
Two interesting recent discoveries bear on this issue. In 1991, an intact 5,000 years old human body protruded from a melting Alpine glacier.
Another body was found in 1999 in a melting glacier in the Yukon Territory in Canada. It is as if our ancestors emerge from the ice to tell us that the earth is warming!
The Himalayas snow/ice sheet is the third largest in the world (after Antarctica and Greenland).
If it continues to melt (see Appendix B), it will affect the water supply of major rivers such as the Indus, Ganges, Mekong, Yangtzee and Yellow rivers all of which originate there.
The snow in the Himalayas is know as the “reservoir in the sky”, it is where nature stores fresh water for use in the summer when the snow melts giving rise to a supply of fresh water, a process that has lasted thousand of years and that has allowed the flourishing of civilizations in those regions.
If such glaciers shrink as the evidence indicates (Appendix B), or even worse, if they disappear, there will be a sharp reduction of fresh water supply for irrigation (agriculture) and cities.
Countries such as Pakistan, India, Thailand, Bangladesh, China and Viet Nam could be severely affected.
Sea-Level Rise. After the last glacial maximum (some 20,000 years ago), global sea level rose by 125 meters and has been within a few meters since 4,000 years ago. After the end of the Little Ice Age, early in 19th century, sea level rose at the rate of 18cm/cy with no measurable acceleration until the mid-20th century when thermal expansion become significant. 
A sea-level rise of 2mm/year becomes 20cm rise in 100 years. If we recall that today 100 million people live within 1 meter of the mean sea level, a number that is bound to increase, we can easily understand the societal and economic impacts of such an increase.
One of the most immediate consequences will be a huge migration of people in the tens of millions, a phenomenon of such a magnitude that the host nations will have hard time coping with such an unprecedented event.
 Sea-level rise has numerous consequences, the primary one is inundation at the expenses of continents and a second one is saltwater intrusion in coastal freshwaters.
The first process has been quantified rather accurately and one can say that a sea-level rise of 1m entails a coastline retreat 1.5km.
Under such circumstances, the rice-growing river floodplains and deltas of Asia would be particularly vulnerable. We should recall that 140 million people in Bangladesh, whose staple food is rice, would lose half of their rice production.
  
Conclusions.
Anyone acquainted with these problems will agree that humanity is facing a looming water crisis. Some concrete numbers bring the point home. Ninety seven per cent of the water on earth (the 1.4 billion cubic km cited above) is in the ocean (no wonder earth is called the blue planet), but ocean’s water is too salty to be used for agriculture and/or drinking.
The remaining 3% is found in rivers, lakes, aquifers and the massive icecaps of Greenland and Antarctica. Only 0.3% of the earth freshwater is found in the easily accessible rivers and lakes. In 1900, the world’s water withdrawl was 500 cubic km per year. By the year 2000, it had climbed to 4,430 cubic km per year, an increase by a factor of eight.
The perplexing fact is that the available renewable fresh water is between (9-14) thousand cubic km per year (to appreciate the significance of this number, let us recall that the water in the earth’s atmosphere is close to the upper value). If we now compare the rate of consumption with what is available, we conclude that we have been withdrawing from 25 to almost 50% of the available freshwater. How long can that continue?
It is tempting to justify such actions as an unavoidable consequence of population growth. But the numbers don’t add up. In 1900, the earth’s population was 1.65 (billion people) while in the year 2000 we were 6.1 (billion people), an increase by a factor of 4, while we have seen that the rate of water withdrawl jumped by a factor of 8, twice as much. It is therefore not only as many we are but how we act. 
Contrary to the anthropogenic CO2 that causes the greenhouse effect and which is truly man made and can therefore be bought and sold, water is not. It is quite different. Water is not a human invention, as we have seen in discussing its origin, it is a free gift from nature. It existed way before life existed.
Do we have the right to sell for profit something that is not ours? Isn’t that the ultimate form of “cosmic theft”?
What will happen when water gets depleted? Unlike oil, carbon and natural gas that may one day disappear forcing us to look for alternative sources of energy, if water disappears, there is no substitute. The disappearance of water means the disappearance of life for the latter was born in it and cannot exist without it.
As the Uzbeck poet M.Salikh wrote: ”You cannot fill an empty river with tears”.

Appendix A

A PARTIAL CHRONOLOGY OF CONFLICT OVER WATER IN THE ANCIENT MIDEAST

3000 B.C.-The Flood
An ancient Sumerian legend recounts the deeds of the diety Ea, who punishes humanity for its sins by inflicting the Earth with a six-day storm. The Sumerian myth parallels the Biblical account of Noah and the deluge, although some details differ.

2500 B.C.-Lagash-Umma Border Dispute
The dispute over the "Gu'edena" (edge of paradise) region begins. Urtama, King of Lagash from 2450 to 2400 B.C., di¬verts water from this region to boundary canals, drying up boundary ditches to deprive Umma of water. His son , cuts off the water supply to Girsu, a city in Umma.

1790 B.C.-Code of Hammurabi for the State of Sumer
Hatnmurahi lists several laws pertaining to irrigation that provide for possible negligence of irrigation systems and water theft.

1720-1684 B.C.-Abi-Eshuh v. Iluma-Ilum
A grandson of Hammurabi, Abish or Abi-Eshuh, dams the Tigris to prevent the retreat of rebels LED by Iluma-Ilum, who declared independence of Babylon. This failed attempt marks the decline of the Sumerians who had reached their apex under Hammurabi.

1200 B.C.-Moses and the Parting of the Red Sea
When Moses and the retreating Jews find themselves trapped between the pharaoh's army and the Red Sea, Moses, miracu¬lously parts the waters of the Red Sea, allowing his followers to escape. The waters close behind them and cut off the Egyp-tians.

720-705 B.C.-Sargon II Destroys Armenian Waterworks
After a successful campaign against the Haldians of Arme¬nia, Sargon II of Assyria destroys their intricate irrigation net¬work and floods their land.

705-682 B.C.-Sennacherib and the Fall of Babylon
In quelling rebellious Assyrians in 695 B.C., Sennacherib razes Babylon and diverts one of the principal irrigation canals so that its waters wash over the ruins.

Sennacherib and Hezekiah
As recounted in Chronicles 32:3, Hezekiah digs a well out¬side the walls of Jerusalem and uses a conduit to bring in wa¬ter. Preparing for a possible siege by Sennacherib, he cuts off water supplies outside of the city walls, and Jerusalem Asurvives the attack.

681-669 B.C.-Esarhaddon and the Siege of Tyre
Esarhaddon, an Assyrian, refers to an earlier period when gods, angered by insolent mortals, create a destructive flood. According to inscriptions recorded during his reign, Esarhad¬don besieges Tyre, cutting off food and water.

669-626B/C. Assurbanipal, Siege of Tyre, Drying of Wells.
Assurbanipal’s inscriptions also refer to a siege against Tyre, although scholars attribute it to Esarhaddon. ln campaigns against both Arabia and Elam in 645 B.C., Assurbanipal, son of Esarhaddon, dries up we lls to deprive Elamite troops. He also guards wells from Arabian fugitives in an earlier Arabian war. On his return from victorious battle against Elam, Assur¬banipal floods h city of Sapibel, an ally of Elm. According to inscriptions, he dams the Ulai River with the bodies of dead Elamite soldiers and deprives dead Elamite kings of their food and water offerings

612 B.C.-Fall of Ninevah in Assyria and the Khosr River.
A coalition of Egyptian, Median (Persian), and Babylonian forces attacks and destroys Ninevah, the capital of Assyria. Nebuchadnezzar's father, Nebopolassar, leads the Babylo¬nians. The converging armies divert the Khosr River to create a flood, which allows them to elevate their siege engines on rafts.

605-562 B.C.-Nebuchadnezzar Uses Water to Defend Babylon.
Nebuchadnezzar builds immense walls around Babylon, us¬ing the Euphrates and canals as defensive moats surrounding the inner castle.

558-528 B.C.-Cyrus the Great Digs 360 Canals.
On his way from Sardis to defeat Nabonidus at Babylon, Cyrus faces a powerful tributary of the Tigris, probably the Diyalah. According to Herodotus's account, the river drowns his royal white horse and presents a formidable obstacle to his march. Cyrus, angered by the "insolence" of the river, halts his army and orders them to cut 360 canals to divert the river's flow. Other historians argue that Cyrus needed the water to maintain his troops on their southward journey, while another asserts that the construction was an attempt to win the confi¬dence of the locals.

539 B.C.-Cyrus the Great Invades Babylon.
According to Herodotus, Cyrus invades Babylon by divert¬ing the Euphrates above the city and marching troops along the dry riverbed. This popular account describes a midnight at¬tack that coincided with a Babylonian feast.

355-323 B.C.-Alexander the Great Destroys Persian Dams.
Returning from the razing of Persepolis, Alexander pro¬ceeds to India. After the Indian campaigns, he heads back to Babylon via the Persian Gulf and Tigris, where he tears down defensive weirs that the Persians had constructed along the riv¬er. Arrian describes Alexander's disdain for the Persians' at¬tempt to block navigation, which he saw as "unbecoming to men who are victorious in battle."

From: P.H.Gleick, Environment, 1994, 36, 7

Appendix B

ICE MELT IN THE WORLD

Arctic Sea Ice
Has thinned by 40 percent in less than 30 years.

Greenland
Has thinned by more than a meter a year on its southern and eastern edges since 1993.

Glacier  Rocky  Mountains, USA.
Since 1850, the number of glaciers has dropped from 150 to fewer than 50. The remaining glaciers could disappear completely in 30 years.

Larsen B Ice Shelf. Antarctic
Calved a 300-square-kilometer iceberg in early 1998. Lost 1,714 square kilometers during the 1998-99 season, and 300 square kilometers during the 1999-2000 season.

Himalayas (Dokriani Bamak Glacier)
Retreated by 20 meters in 1998, compared  with 16.5 meters over the previous five years.

Tien Shan Central Asia
Twenty-two percent of glacial ice volume has disappeared in the past 40 years.

Caucasus Russia
Glacial volume has declined by 50 percent in the past century.

Alps Western Europe
Glacial volume has shrunk by more than 50 percent since 1850. Glaciers could be
reduced to only a small fraction of their present mass within decades.

Kilimanjaro Tanzania
Ice cap shrunk by 33 percent from 1989 to 2000. Could disappear by 2015.

Quelccaya Andes Peru
Rate of retreat increased to 30 meters a year in the 1990s, up from only 3 meters a year;
will likely disappear before 2020.

From L.R.Brown, Eco-Economics,2001