Essential Questions

This exhibition explores where water occurs on Earth, how it's used, and how we can become better stewards of our water planet. You can use the essential questions below to connect the exhibition's educational themes to your curriculum.

Why is water essential to all life?
Life started in water, and the properties of water drove the course of its evolution. About two-thirds of the human body is water. Every living organism needs water to survive. Space probes look for signs of water on other planetary bodies to determine whether they are, or might have been, home to life as we know it.

  • Water is crucial to all ecosystems. Along with temperature, the presence or absence of water determines what lives where on Earth and in what quantities. Species have adapted exquisitely to an amazing variety of freshwater and marine habitats. The ocean is home to the largest known diversity of life on the planet. Ingenuity enables our species to live in environments that range from very wet to very dry.

Tropical cyclones like Katrina, above, are fueled by heat released when moist air rises and the water vapor it contains condenses. ©NASA - Click to enlarge
Tropical cyclones like Katrina, above, are fueled by heat released when moist air rises and the water vapor it contains condenses. ©NASA
(click to enlarge)
How does water shape the planet and regulate its climate?
Water covers more than two-thirds of the Earth's surface, an abundance that is unique in our solar system. It continuously changes from one form to another as it moves through the crust, oceans, and atmosphere in a vast process known as the "water cycle." The oceans store heat in great quantities. By storing and transporting heat, as ocean currents and atmospheric vapor, water is an extremely important modifier and driver of climatic patterns.

  • Earth system processes are made possible by the unique physical and chemical properties of water. The water molecule (H2O) is very stable, is an excellent solvent, and requires a lot of energy to change temperature and states. These properties are the basis of the fundamental connection between life and liquid water. Water exists in three states on Earth: liquid (clouds, rivers, and aquifers), gas (water vapor), and solid (ice, snow, glaciers, and icebergs). Unlike most substances, water is less dense in its solid form than in its liquid form.

Drip irrigation systems like this one use tubes or pipes on or under the soil to deliver water. This low-pressure method is efficient and loses less water to evaporation than other forms of crop irrigation. ©Leonardo Diaz Romero / AGE Fotostock - Click to enlarge
Drip irrigation systems like this one use tubes or pipes on or under the soil to deliver water. This low-pressure method is efficient and loses less water to evaporation than other forms of crop irrigation. ©Leonardo Diaz Romero / AGE Fotostock
(click to enlarge)
How is water distributed across the planet?
Earth's water is a finite resource. The availability of water on land varies due to weather patterns, evaporation rates, and other factors. Most water is contained in the oceans. Less than 3% of all water on Earth is fresh, and less than one-third of that is liquid.

  • Water fuels the growth of human settlements. Access to water has shaped the distribution and spread of homes, farms, and cities across millennia. People live along coastlines, rivers, and lakes because water is useful for food, sanitation, transportation, power, and many industrial processes. Where fresh water is not readily available, people have used many technologies to collect and carry it. Its value and beauty make water a potent symbol in many cultures.

  • Freshwater and marine systems are fragile and susceptible to human misuse. Rivers, lakes, and groundwater can be depleted or polluted, making them unavailable or unsuitable for life. Oceans are under threat from chemical pollution, overfishing, sedimentation, habitat destruction, and other factors. All species, including humans, live "downstream"—all living things use water already used by others. Billions of people live without safe water and sanitation, and global thirst is growing along with the world's population.

How can we be better stewards of our water planet?
We need to use water more efficiently, conserve where possible, protect water quality, and make informed decisions to balance competing demands among species. While the world's aquatic systems have a limited capacity to absorb waste, they can be resilient. Actions we take today can revitalize and sustain this precious resource.

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Water: H2O=Life Online Educator's Guide