Part 4—Draw Connections Between the Local and Global Processes

Reservoirs and Fluxes

Today, Earth system scientists are studying reservoirs and fluxes in attempts to understand their impact on Earth's environment. What are reservoirs and fluxes? Here is a simple example. There is a fixed amount of water on Earth. That water is divided up into smaller parts, called reservoirs. Earth's largest reservoir of water is in the ocean. Another reservoir is the water that is frozen in ice caps and glaciers. A third reservoir is the water that is in the ground. Another reservoir is atmospheric water, called water vapor.

• Can you think of other reservoirs of water on Earth?
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  Other reservoirs of water on Earth include the water in all living things (people, tomatoes, birds, etc.) The term used to describe all of the living things on Earth is the biosphere. Another reservoir is all of the fresh water on Earth, which includes lakes, ponds, bogs, rivers, streams, and brooks.
  
  

Flux refers to the movement of water from one reservoir into another. In the work you just completed for Greenville, PA, the reservoir of water in the soil became smaller as spring advanced towards summer, and just the reverse happened as fall advanced towards winter.

• Which reservoir do you think gained water in the summer? In other words, to which reservoir did that soil moisture flow?
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  Note: Students may need to depend on their personal observations to fully answer this question since not all of this information was included in the content of the Chapter. As air temperatures rise above freezing, soil moisture at or close to the surface will evaporate into the atmosphere. As the air continues to warm and plants increase their volume (new leaves, twigs, etc), water moves from the soil into plants. Plants don't simply store all of this additional water; they also release water into the atmosphere (transpiration). So water levels in both vegetation and the atmosphere increase.
  
  

Flux at Various Scales

Although you have studied data for just one location, the movement of water between reservoirs happens all over Earth. During the Ice Ages, the reservoir of frozen water in glaciers, ice caps, and sea ice all increased, while other reservoirs, such as water in the oceans, decreased. Sea level was lower during the ice ages than it is now.

• How do you think Earth's water reservoirs might change if Earth became a lot warmer than it is today?
• What else do you think would change if the water reservoirs changed due to a warmer Earth?
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Responses will vary. There would be less water in glaciers, sea ice, and ice caps, because they would melt, and this would add more water to the ocean. There would also be more water in the atmosphere because there would be more evaporation. There might also be more transpiration from vegetation, and probably more plants to hold more of the Earth's water.

There will be fewer animals and plants that have adapted to live in cold regions. There would be more animals and plants that have adapted to live in warm regions. There would be more water in the ocean, and less land above water; coastlines would change. There would be less fresh water available; regions of the Earth that now depend on getting fresh water from rivers that flow from glaciers would no longer have those sources.

Now that you know how to find GLOBE data for other places around the world, and you know how to use the GLOBE Graphing Tool, you can look for evidence of flows in places other than in Greenville, PA.