Objective: To make students consider what they have learned about the scientific use of models.

Goal: Students will:

• Read and comprehend the article.
• Use questions for thought to consider the content they have read.

Standards met: LA1, LA2, LA3, LA7, LA8, LA9, LA11

Procedure:

• In class or as a homework assignment have students read the Climate Models article below.
• Ask students to respond verbally or in written form to the questions for thought and or comprehension questions.

Assessment:

• Class discussion questions and/or written comprehension and questions for thought.

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Climate Models Help Scientists Understand Global Shifts in Water Availability
Released: 11/16/2005 4:34:29 PM

USGS scientists have a clearer picture of global shifts in water availability after examining a century of streamflow measurements from 165 locations around the world. Simulations from an ensemble of 12 global climate models compared favorably with the historical streamflow data. The scientists discovered that climate models have significant relevance in simulating historical long-term trends in streamflow around the world. That finding lends credibility to the same models’ streamflow forecasts for the coming decades.

And what do the models show about the future? The models predict 10 to 40 percent increases in runoff in eastern equatorial Africa, the La Plata basin and high latitude North America and Eurasia by the year 2050. They also predict 10 to 30 percent decreases in runoff in southern Africa, southern Europe, the Middle East and mid-latitude western North America by the year 2050.

The article, "Global pattern of trends in streamflow and water availability in a changing climate," to be published tomorrow in the journal Nature, examines water-availability projections of climate models. The USGS scientists discovered that climate models are useful for simulating regional historical long-term trends in streamflow around the world.
Lead author Christopher Milly explains the complex pattern of streamflow change by noting a basic fact of thermodynamics, "A warmer atmosphere can carry more water. So, warmer winds can deliver more water to a region, but they can also take more away. This give-and-take plays out differently in different parts of the world, causing decreases in water supply here, and increases there."

Water availability is directly related to climate. However, there is no simple relationship for all regions between future temperatures and future water resources. Some regions may experience increases in precipitation and run-off while other regions may experience decreases.

According to the study’s authors, changes in sustainable water availability could have considerable regional-scale consequences for economies as well as ecosystems. Water availability on the continents is important for human health, economic activity, ecosystem function and geophysical processes.

The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.

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Questions for Thought – Student Sheet

1. How does this article relate to what you learned during the Models science lesson?
   
   

2. Why do scientists use models to predict what will happen in the future with the world’s climate?
   
   
   

3. In the third paragraph what does the author tell us about Miller’s findings on climate change as it relates to different parts of the world?
   
   

4. Give concrete examples from your previous knowledge of why you think that water has such an impact on the economics and ecosystems of a region.

5. As it relates to the last paragraph explain how you think humans can “manage” the environment.

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