What’s the Big Deal About Water, Anyway?
Water. H2O. Dihydrogen monoxide. Regardless of what we call it, there is no doubt that this simple molecule is crucial to human survival. We rely on it for everything from drinking, to showering, to cooking food, to watering crops. Up to 60% of the adult human body is composed of water, and without it, a person would only be able to survive for about a week at most.
Beyond the basic necessity of water, nearly all of us are also familiar with the importance of water conservation. Turn off the tap while brushing your teeth! Take shorter showers! Collect rainwater to water your plants! These mantras are well-engraved into our minds, so much so that they seem to be common sense. Of course we should conserve water — the prospect of such a critical resource running out is far too scary for us to act otherwise.
But how exactly can water “run out”? Water is, after all, a renewable resource. From as early as elementary school, we’ve learned that water transitions through a number of forms via the hydrologic cycle. The liquid water that we can use can progress along two broad paths: in the first, the water evaporates to become water vapor in the atmosphere before eventually condensing and returning to Earth’s surface in the form of precipitation. In the second, the water infiltrates through the ground and enters underground reservoirs of groundwater, known as aquifers. Neither path leads to any net loss or gain of water; in fact, the same supply of water has been continuously recycled since the very creation of our planet. So, why should we need to worry about how much water we use if it is all eventually returned by nature? What, in short, is the big deal about water?
To answer this, a key distinction needs to be made between global water and local water. It’s true that the total supply of global water can’t be depleted; locally available reservoirs, on the other hand, absolutely can. Human communities rely on large, easily accessible reservoirs of fresh water, namely aquifers, lakes, and rivers. The water extracted from these reservoirs, however, does not always return to the same source after being recycled. Instead, it is relocated and dispersed, making it temporarily inaccessible for large-scale human use. In order for water to be sustainable, the rate of regional water consumption cannot exceed the rate at which dispersed water is able to return to local reservoirs.
Perhaps a simpler analogy would be to think of water as a stack of dishes at a restaurant. The total number never changes, but as they are distributed to tables, the amount of dishes still available for use decreases. For the dishes to be usable again, they must be washed, dried, and returned to the initial stack. If, at any point, the rate at which dishes are needed exceeds the rate at which they are restocked, a shortage ensues.
Due to population growth, the rate of water consumption is increasing, but the supply of fresh water remains constant at best. To make matters worse, when the residues of pesticides, herbicides, and fertilizer used in agriculture are washed into the earth by rainfall, both groundwater and surface reservoirs can be contaminated. This, along with other forms of water pollution, actually reduces the amount of available clean water. We are, speaking by analogy, hurtling toward a shortage of dishes, and the consequences are far more dire than a few unhappy customers.
In 2011, approximately 1.1 billion people around the world did not have access to clean drinking water. As the global population increases, the number of people living under water stress is projected to increase to over five billion by 2050. Due to global climate change, the possibility of increasingly severe droughts may threaten to drive that number even higher.
So, what’s the big deal about water, anyway?
Everything. And even that may be an understatement.
Works Cited
Fishman, Charles. The Big Thirst, Free Press, 2011.
Mann, Charles C. The Wizard and the Prophet, Alfred A. Knopf, 2018.
“The Water in You.” The USGS Water Science School. USGS, https://water.usgs.gov/edu/propertyyou.html. Accessed 25 Aug. 2018.
“Water Stress to Affect 52% of World’s Population by 2050.” Water Footprint Network. Water Footprint Network, http://waterfootprint.org/en/about-us/news/news/water-stress-affect-52-worlds-population-2050/. Accessed 25 Aug. 2018.
+++
To learn more about making your voice heard, visit us at our website. To take action, sign and share our petition to safeguard science in our schools, communities, and futures. To be a part of our conversation, join us on Twitter@ScienceTeens, on Instagram at scienceteens, and on Snapchat at march4science.
