Water Is Not The New Oil
In the midst of the clamor over global warming, greenhouse gas emissions and world energy supplies another, perhaps more immediate, environmental catastrophe is gathering momentum—the world wide shortage of fresh water. Though eclipsed in America by pictures of oil-soaked pelicans and fouled coastal wetlands, this potentially more disastrous and more permanent problem has been ignored by politicians and the public for decades. Experts are warning that by 2050 fully 45% of humanity may be chronically short of water. Unlike the eventual depletion of the world's oil supplies, there is no substitute for H2O.
Water is amazing stuff, made up of molecules comprising two atoms of hydrogen and one of oxygen, H2O has been found by astronomers in the farthest reaches of the Universe. Present on Earth since early in its formation, water is essential to the formation of granite, the rock that buoys the continents atop heavier crust and magma. It also fills the world's oceans and makes possible the planet wide infestation known as Life. The human body is about 60% water and H2O is the most important greenhouse gas, helping the atmosphere to retain enough warmth to permit living things to thrive on what would otherwise be a frozen lifeless plant.
Though we think of nature dominated by the green of photosynthesizing plants, when viewed from space the dominant color of our planet is blue mixed with swirls of constantly changing white clouds. Ours is a water planet, the surface area covered by water is 70% while land only takes up 30%. Most of this surface is ocean, over 97% of the total. So while our world possesses a tremendous amount of water, some 321,000,000 cubic miles (1,338,000,000 km3) of the stuff according to the USGS, most of it is salty.
Relative volume of the ocean and Earth
While the volume of water contained in Earth's oceans seems like a lot, and it certainly is on a human scale, both the ocean and atmosphere are merely thin shells surrounding the solid parts of our planet. If every drop of water in the world was collected in a sphere, it would be just 869 miles in diameter. The illustration above shows a comparison of the volume of water and the size of Earth. The ball of water seems shockingly small, with a volume of only 338 million cubic miles (1.41 billion km3).
A special report in the Economist, “For want of a drink,” gives the total amount of salt water as 97.5%. “Of the 2½% of water that is not salty, about 70% is frozen, either at the poles, in glaciers or in permafrost,” they report. “So all living things, except those in the sea, have about 0.75% of the total to survive on.” It is on this small amount that all Earth's land life—plants, animals and people—depend.
In the past this has been sufficient, but things are changing with the ever growing human population. The Economist report states the looming water crisis this way:
When, 60 years ago, the world’s population was about 2.5 billion, worries about water supply affected relatively few people. Both drought and hunger existed, as they have throughout history, but most people could be fed without irrigated farming. Then the green revolution, in an inspired combination of new crop breeds, fertilisers and water, made possible a huge rise in the population. The number of people on Earth rose to 6 billion in 2000, nearly 7 billion today, and is heading for 9 billion in 2050. The area under irrigation has doubled and the amount of water drawn for farming has tripled. The proportion of people living in countries chronically short of water, which stood at 8% (500m) at the turn of the 21st century, is set to rise to 45% (4 billion) by 2050. And already 1 billion people go to bed hungry each night, partly for lack of water to grow food.
A special report in the Economist, “For want of a drink,” gives the total amount of salt water as 97.5%. “Of the 2½% of water that is not salty, about 70% is frozen, either at the poles, in glaciers or in permafrost,” they report. “So all living things, except those in the sea, have about 0.75% of the total to survive on.” It is on this small amount that all Earth's land life—plants, animals and people—depend.
In the past this has been sufficient, but things are changing with the ever growing human population. The Economist report states the looming water crisis this way:
When, 60 years ago, the world’s population was about 2.5 billion, worries about water supply affected relatively few people. Both drought and hunger existed, as they have throughout history, but most people could be fed without irrigated farming. Then the green revolution, in an inspired combination of new crop breeds, fertilisers and water, made possible a huge rise in the population. The number of people on Earth rose to 6 billion in 2000, nearly 7 billion today, and is heading for 9 billion in 2050. The area under irrigation has doubled and the amount of water drawn for farming has tripled. The proportion of people living in countries chronically short of water, which stood at 8% (500m) at the turn of the 21st century, is set to rise to 45% (4 billion) by 2050. And already 1 billion people go to bed hungry each night, partly for lack of water to grow food.
Most liquid freshwater is in underground aquifers or similar formations, accessed using wells. The rest falls as rain, collecting in lakes and reservoirs or in rivers where it is eventually transported to the sea. All the H2O in freshwater aquifers, lakes and rivers must constantly be replaced by precipitation—water vapor condensing in the atmosphere to fall as rain or snow. Where this water comes from and where it goes is shown in the graphic, taken from the report, on the left.
Water distribution
The fact is, there is a hundred times more water in the ground than is in all the world's rivers and lakes. Surface-water sources, such as rivers, only constitute about 300 cubic miles (about 1/10,000 of one percent of Earth's total water). Moreover, that water is not evenly distributed—just nine countries account for 60% of all available fresh supplies. Among the water rich countries only Brazil, Canada, Colombia, Congo, Indonesia and Russia have an abundance. While America is relatively well off, China and India, with over a third of the world’s population between them, have less than 10% of its water.
Worldwide, agriculture accounts for 70% of all water consumption, compared with 20% for industry and 10% for domestic use. In developed nations, however, industries consume more than half of the water available for human use. Belgium, for example, uses 80% of its water for industry. World demand for freshwater is increasing by 17 trillion US Gallons (64 trillion liters) a year. Increasingly, this demand is being met by sinking wells into underground aquifers, tapping water supplies that are hundreds or thousands of years old. Freshwater withdrawals have tripled over the past 50 years.
Unfortunately, many countries are consuming underground water resources at nonrenewable rates. From the United States to India and China, the quantities being withdrawn exceed the annual recharge. In the Hai river basin in China, for example, deep-groundwater tables have dropped by up to 290 feet (90 m). In cities like Bangkok, Buenos Aires and Jakarta, aquifers are overdrawn, polluted or contaminated by salt. The 20 million inhabitants of Mexico City draw over 70% of their water from an aquifer that, at current extraction rates, will run dry in less than 200 years.
In the US, parts of the Ogallala aquifer, which covers 174,000 square miles (450,000 km2) running beneath eight states, are seriously overdrawn. The water-permeated thickness of the Ogallala aquifer, also known as the High Plains aquifer, ranges from a few feet to more than 1000 feet (300 m). The depth of the water below the surface of the land ranges from almost 400 feet (122 m) in parts of the north to between 100 to 200 feet (30 to 61 m) throughout much of the south. Present-day recharge of the aquifer with fresh water occurs at a slow rate; this implies that much of the water in the aquifer is paleowater, dating back to the time of the last ice age glacial period.
In parts of the area, farmers began using ground water for irrigation extensively in the 1930s and 1940s. Estimated irrigated acreage in the area overlying the High Plains aquifer increased rapidly from 1940 to 1980. Withdrawals from the Ogallala Aquifer for irrigation amounted to 21 million acre feet (26 km3) in 2000—slightly greater than the historical discharge rate of the Colorado River. As of 2005, the cumulative depletion totaled 253 million acre-feet (312 km3). Some estimates say the Ogallala will dry up in as little as 25 years.
It is a similar story around the world: rising populations require greater agricultural production, which demands more freshwater. In terms of water withdrawal, the US is in third place behind India and China. Remote sensing technologies are being used to track groundwater levels worldwide at both large and small scales. NASA's Gravity Recovery and Climate Experiment (GRACE) performs large-scale, long-term analysis using changes in gravity at the earth’s surface to examine the removal of groundwater from large aquifers worldwide.
World water withdrawal
GRACE measurements show that India’s breadbasket region may be running out of water. According to NASA satellite data, reported in Nature, groundwater levels in aquifers in northwest India have declined one foot per year over the past decade. Researchers conclude the loss is due almost entirely to groundwater pumping and consumption by human activities, such as irrigating cropland. As a result, aquifers are being drained much faster than they can be replenished by rainfall or river runoff.
Water is a finite resource but, fortunately, a constantly renewed one. Water evaporates from the world's salty seas, traveling withing the atmosphere to the far reaches of the planet to fall as rain or snow. For most of man's history, people have been dependent on nature for this supply of fresh water. Even today, large portions of the world's population depend on the Monsoon to bring water for drinking and agriculture—when the Monsoon fails, people can go hungry and even starve to death.
Earth's water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go in a hurry. Since the water cycle is truly a “cycle,” there is no beginning or end. Water changes state among liquid, vapor, and ice at various places in the water cycle, with these processes happening sometimes quickly and sometimes over millions of years.
The water cycle
While some have tried to tie increasing water shortages to global warming that link is weak at best. The UN's own “3rd United Nations World Water Development Report: Water in a Changing World ” (WWDR-3) puts it this way:
While climate change will create important pressures on water, it is not currently the most important driver of these pressures outside the water sector. The most important drivers – forces and processes generated by human activities – are demographics and the increasing consumption that comes with rising per capita incomes.
For all of human history, water use has risen with increasing wealth. Mankind's earliest civilizations grew up in the river valleys of the Nile, the Indus, the Yellow, and the Tigris & Euphrates. Today people tap the unseen rivers that flow beneath the surface of our planet, but even those resources are limited. Though water used in agriculture is not destroyed, as oil is when it is burned, an estimated 85% of irrigation water escapes into the atmosphere by evaporation. This water is no longer available for human use until it condenses and falls back to Earth, somewhere.
Petroleum takes about 100 million years to form and a convergence of the right biological and geological circumstances. For all intents and purposes, when we have used up the current deposits of oil stored within Earth's crust it is all gone. Happily, there are other sources of energy available—nuclear, wind and solar—but this is not the case with water. True, freshwater is renewable, but that renewal takes place at nature's own pace. In essence, nature keeps the biosphere on a strict water allowance, and that means mankind must learn to live with the finite supplies we are given.
The hay farms of Saudi Arabia won't outlast their oil
Though some nations make new freshwater using desalinization this is a very expensive proposition and, with the world already facing energy shortages, not a viable large-scale option. Fortunately, there is great room for improvement in how we utilize our water resources, particularly in agriculture. Many farmers in the Texas High Plains, which rely heavily on the underground source, are now turning away from irrigated agriculture, allowing underground aquifers to recover. Drip irrigation has an efficiency of up to 95% with no runoff, no erosion and little evaporation loss. With a population approaching 10 billion by 2050, humanity will have to cooperate and conserve the world's freshwater resources. Otherwise we may find ourselves in the same position as our ancient ancestors, fighting each other for access to waterholes.
