Now that we are well into spring, it’s become clear that the American West is facing another year of extreme dryness. According to the US Drought Monitor, all 11 western states are experiencing some form of drought, with huge swaths of the Great Basin and Colorado Plateau enveloped in the most severe category—"exceptional.” Parts of Utah and Arizona are beginning to resemble the surface of Mars, as huge dust storms roll across the landscape, turning the air an ominous red. 

We live in a time of intensifying aridity. Droughts across the world, from the tip of South America to the Horn of Africa, are deepening and water shortages are becoming more severe. According to one recent study, 3.8 billion people—half of the world’s population—live in areas facing water scarcity. A growing body of evidence suggests that our industrial activities are playing a significant role in the aridification of our planet. In hydrological matters, the human species suffers from cognitive dissonance on a mass scale: We know water is critical to life, but we continue to behave in a way that jeopardizes this precious resource.

“If there is magic on this planet,” the great science essayist Loren Eiseley wrote, “it is contained in water.” What is it, exactly, about this simple molecule, made up of two hydrogen and one oxygen atoms, that makes it indispensable to life? Water acts as a “universal solvent” capable of dissolving and transporting a variety of nutrients across a wide range of temperatures. It is the medium—the broth in the soup of life—that allows an array of life-giving chemical reactions to take place. It is such an essential ingredient for life as we know it, that the search for life elsewhere in the universe is essentially a quest for water. In an astronomical context, Eiseley’s statement could be rephrased: “If there is magic off this planet, it is contained in water."

So far, we know that there are a few places in our own solar system, including Mars and the moon, that hold water, but it is frozen solid—too cold to harbor life. The most interesting of water-bearing planetoids is the pale world of Enceladus, a small moon of Saturn, which conceals a salty ocean under its icy crust. Here, NASA satellites have captured massive geysers shooting water vapor and ice crystals hundreds of miles into space. 

If water exists anywhere out there like it does on Earth, it’s on exoplanets far beyond our solar system. To locate them, scientists look for the telltale periodic dimming of the stars around which they orbit. (Imagine suspending a baseball from a string and moving it in front of a lightbulb; the light will appear to dim temporarily as the ball passes between it and the observer.) These intermittent flickers, known as “transits,” allow researchers to determine the basic characteristics of exoplanets—their size, for example, or how far away they are from their parent stars.  

In order to get a more complete picture of what these distant worlds are like, scientists carefully analyze the light that passes around them, looking for unique spectral signatures that reveal what elements make up their atmospheres. In 2019, researchers from University College London used spectral analysis to discover, for the first time, water vapor in the atmosphere of a planet well outside our solar system. Dubbed K2-18b, this world, 142 light-years away, inhabits a narrow orbital band around its parent star—often referred to as the goldilocks zone—where liquid water is possible. 

Eight times the mass of our own planet, K2-18b is one of an emerging class of rocky planets known as Super-Earths. If this distant world does harbor life, however, it is surely far different than any found on our own planet. For starters, its gravity is 37 percent stronger than what we experience on our home planet (a person weighing 150 pounds on Earth, would be 50 pounds heavier on this Super-Earth). Moreover, K2-18b makes one complete revolution around its sun every 33 days. Because of its short orbital period, scientists believe that the planet might be “tidally locked,” meaning that one side always faces toward its host star, while the other side faces away, shrouded in perpetual night. 

Chris McKay, a planetary scientist at NASA’s Ames Research Center, has challenged scientific orthodoxy and asserted that water may not, in fact, be a prerequisite for life. He believes that other compounds, including liquid methane and ethane, could replace H2O as a universal solvent. These hydrocarbon compounds are found, for example, in large quantities on Saturn’s largest moon, Titan. 

Titan’s surface sits at an unimaginably frigid -290 degrees Fahrenheit. But these extreme temperatures mean that methane and ethane exist in abundance, in massive “lakes” scattered like inkblots across its surface. Both compounds have properties similar to water in that they adhere to one another and are capable of dissolving a large array of organic molecules. Lifeforms on Titan, if they exist, would require different metabolic machinery from plants and animals on Earth. Scientists speculate that their cells might be protected by exotic membranes called “azotosomes,” comprised of nitrogen, carbon, and hydrogen. 

All of which is well and good for lifeforms capable of assimilating liquid methane—if they happen to exist. But, of course, we humans, along with all of the other organisms on this planet, are water-derived and water-dependent. As stewards of Earth, we must do all we can to protect this vital resource.  

On that account, we are doing a pretty poor job. Maybe it is because water is a ubiquitous substance on our planet that we tend to take it for granted and abuse it.

For decades, our extractive industries have treated water not as if it were the critical ingredient for life, but as garbage. During the gold rush, miners used water to hydraulically blast mountains into oblivion in search of precious metal. In that transaction, the miners collected relatively tiny quantities of gold while ravaging entire rivers and poisoning water sources across the western United States. Today’s oil companies, in a similar vein, blast tens of millions of gallons of water annually into the earth, to hydraulically fracture oil deposits. In the process, they generate lakes worth of hydrocarbon-tainted wastewater. Meanwhile, anthropogenic climate change, driven by the unchecked burning of fossil fuels, is greatly intensifying water scarcity in certain parts of the planet. 

One way or another, whether it is by way of repairing the damage we have caused and conserving what remains, or by our own destruction, we must eventually learn this key lesson: Without water we are nothing.