“Human nature is like water. It takes the shape of its container.”
—Wallace Stevens
“It is said by the Eldar that in water there lives yet the echo of the Music of the Ainur [the immortal Spirits existing before the Creation]…”
—J. R. R. Tolkien, Silmarillion
“Life in us is like the water in a river.”
—Henry David Thoreau
“They both listened silently to the water, which to them was not just water, but the voice of life, the voice of Being, the voice of perpetual Becoming.”
—Hermann Hesse, Siddartha
“All the rivers run into the sea; yet the sea is not full; to the place from where the rivers come, thither they return again.”
—Ecclesiastes 1:7
The amount of water on our planet is relatively fixed. Water exists within different containers, such as glaciers, rivers or the oceans, above ground or below ground, but there is almost no change in the absolute amount because very few molecules of water escape our atmosphere into space. Water, thus, cycles through the physical and biological realms on our planet, a natural re-circulating system that many refer to as the life-blood of our planet. The pattern of water’s distribution and particularly the availability of fresh water determines where organisms can live, what crops can be grown and even the nature of human societies.
Water is the one substance that all macroscopic and most microscopic life cannot do without. Life can exist without air or oxygen but it cannot survive without water. Moreover, life is primarily comprised of water. An adult human, for example, is 50-60% water on average. And because of the cycling process across time and geography, water provides an inexorable connection among all living things. Water flows through all of us.
The estimates are that there is 1.4 x 109 km3 of water on the planet of which 3.5 x 107 km3 is freshwater[1]. Not all of the freshwater is currently available to us; for example, the water that is sequestered in geologically sealed aquifers well below the earth’s surface is not accessible. The largest majority of freshwater exists in the form of glaciers and snowmelt (68.6%), while groundwater comprises the next largest source (31.4%). Lakes hold only 0.5% and rivers, despite their magnificence, hold only six one-thousandths of a percent (.006%). The water contained in the biological realm is estimated to be 1.1 x 103 km3 or only 0.003% of the total freshwater on the planet.
The measure of how water circulates among the various “containers” is known as residence time or renewal time: the time that an average molecule resides within a container or is replaced within that container. So, for example, an average molecule of water resides in the ocean for 25,000 years, in glaciers and snow cover for 56 years, in rivers for 18 days, and in the atmosphere for 9 days. Biological water has a much shorter residence time – only several hours; remember that this is an average over all life forms.
These data allow us to realize just how connected we are through water. Using three hours as the average residence time of a molecule of water in the biological realm, it is easy to show that an average molecule of water can flow through all life forms in 4,000 days, approximately 11 years. Thus, on average, a water molecule in our body spent the previous 11 years traveling through all other life forms, including humans, before arriving in us. This means that our body water has been recycled through both the biosphere and the hydrosphere.
But we can ask a more interesting question: what is the connection between the water in any of our bodies and all other humans who have lived? According to the UN, modern humans (Homo sapiens) appeared on the earth approximately 50,000 years ago. Demographers[2] have estimated that there have been 108 billion people who have lived since then. Using some average physiological data for contemporary humans and a residence time of 14 days, I estimate that an average water molecule could pass through all of humanity in approximately 100 years. Moreover, a water molecule in our bodies has passed through one billion other people. Thus, as we approach 100 years old, we approach the possibility of having shared water with all 108 billion humans who have ever lived. Water ties us all together—a common bond. The freshwaters that have passed through the human realm have recorded our deeds, triumphs and tragedies.
Ancient peoples treated waters in two ways: i) as a revered substance; and ii) as a carrier of waste. It is not surprising that in many cultures or religions water plays a critical role in creation myths (e.g., Hindus, Balinese and Pe’aroá) or rituals (e.g., Judaism, Christianity, Ashuara).
Despite its role as the giver of life and recorder of history, water is now and has often been treated capriciously. Because it flows from us and by us, we see water as a source to remove waste and to pollute. A sign on the edge of a creek in 1984 in the village of El Real, upper Tuira River basin, eastern Panama, read “Maintain the cleanliness of the village, throw your garbage in the river.” A practice not unprecedented in the United States or elsewhere. The Cuyahoga River in Ohio, regarded as the most polluted in the US from garbage and industrial waste, caught fire 13 times between 1868 and 1969; the last fire, though not the most potent, reached a height of five stories above the water. Many rivers and lakes around the world have been treated as sewers in ancient and modern times. Clean-up efforts in many rivers (e.g., the Rhine, the Connecticut) have cost millions of dollars and devastation to aquatic life may never be restored.
The biosphere is completely dependent upon and connected by the water cycle. Climatic changes due to global warming are having a profound impact upon the water cycle. Many river systems around the world depend upon snow pack and glacial melt for their water. Increased air temperatures have changed the type of precipitation in many mountainous regions from snow to rain. The result in areas such as the Rockies and the Tibetan Plateau is higher winter flows, less snow pack and very low summer flows. Another conundrum is that as the global climate warms, more surface water will evaporate. Increased atmospheric water will increase precipitation but where the rain will fall is open to question and it is predicted[3] that many arid regions will become even drier over this century.
The main point is that water is a precious commodity that we need to use and treat with respect. Water flows around the planet and becomes a crucial fabric of our existence and life. The water in our bodies connects us with all other life forms and, indeed, with all other humans who have lived. In the prescient words of Yoko Ono:
“You are water,
I’m water,
we’re all water in different containers.
That’s why it’s so easy to meet,
someday we’ll evaporate together.”
Barry Chernoff is the Schumann Professor of Environmental Studies, Biology and Earth & Environmental Sciences. He is the Director of Wesleyan’s College of the Environment.