About This Module

Topics: Climate, Greenhouse Gases, CO₂ -driven Changes, Temperature Anomalies
Grade Levels: 9-12

Scenario

Global climate change is a change in the long-term weather patterns that characterize the regions of the world. The term "weather" refers to the short-term changes in temperature, wind, and/or precipitation of a region. Weather is influenced by the sun and many other factors. The sun heats Earth's atmosphere and its surface, causing air and water to move around the planet. The result can be as simple as a slight breeze or as complex as the formation of a hurricane.

Some of the sun's incoming short wave radiation is reflected back to space by aerosols—very small particles of dust, water vapor, or chemicals in Earth's atmosphere. In addition, some of the sun's energy that enters Earth's atmosphere is reflected into space by the planet's surface. The reflectivity of Earth's surface and clouds is called albedo. Reflection of solar radiation by aerosols, clouds, and the surface all cool the planet.

The greenhouse effect is a planetary warming process. Some of the radiation from the sun is absorbed by Earth's surface. As the surface heats, it emits long wave radiation (in the infrared) toward the atmosphere. There some of this long wave radiation is absorbed by certain gases called greenhouse gases. These include carbon dioxide (CO₂), chlorofluorocarbons (CFCs), methane (CH₄), nitrous oxide (N₂O), tropospheric ozone (O₃), and water vapor (H₂O). Each molecule of greenhouse gas becomes energized by the long wave radiation. The energized molecules of gas then emit long wave radiation in all directions, some toward the Earth, warming the planet and increasing Earth's temperature. Note that the warming mechanism for the greenhouse effect is not exactly the same as the warming mechanism of greenhouse walls. While greenhouse gases absorb long wave radiation, then emit that energized long wave radiation in all directions, greenhouse walls physically trap heat inside of greenhouses and prevent it from escaping to the atmosphere.

The greenhouse effect is a natural occurrence that maintains Earth's average temperature at approximately 60 degrees Fahrenheit. The greenhouse effect is a necessary phenomenon that keeps all of Earth's heat from escaping to the outer atmosphere. Without the greenhouse effect temperatures on Earth would be much lower than they are now, and the existence of life as we know it on this planet would not be possible. However, increasing greenhouse gases in Earth's atmosphere could increase the greenhouse effect. This could result in an increase in mean global temperatures as well as changes in precipitation patterns.

When weather patterns for an area, influenced by temperature, change in one direction over long periods of time, they can result in a net climate change for that area. The key concept in climate change is time. Natural changes in climate usually occur over such long periods of time that they often are not noticed within several human lifetimes. This gradual nature of change enables plants, animals, and microorganisms to evolve and adapt to the new temperatures and precipitation patterns.

The real threat of climate change lies in how rapidly the change occurs. Scientists are in agreement that global temperatures have increased about 0.8 degrees Celsius since 1900. These temperature changes are depicted in the graph of global land-ocean temperatures shown below from NASA’s GIS Surface Temperature Analysis. The graph (below) shows that increases in mean global temperature have occurred recently at greater rates. Further evidence suggests that future increases in mean global temperature may occur at a rate of  0.2 degrees Celsius (0.4 degrees Fahrenheit) each decade.

Source: NASA-GISS surface temperature analysis: http://climate.nasa.gov/key_indicators#globalTemp

Image description: This graph illustrates the change in global surface temperature relative to 1951-1980 average temperatures. Global surface temperatures in 2012 were the ninth warmest on record. (Source: NASA/GISS) The gray error bars represent the uncertainty on measurements. This research is broadly consistent with similar constructions prepared by the Climatic Research Unit and the National Atmospheric and Oceanic Administration.

The geological record—the physical evidence of the results of processes that have occurred on Earth since it formed—provides evidence of climate changes similar in magnitude to those in the maps above. This means during Earth's history there have been changes in global temperatures similar to these changes. However, the past changes occurred at much slower rates, and thus they were spread out over long periods of time. The slow rate of change allowed most species enough time to adapt to the new climate. The current faster rates of temperature change, on the other hand, might harm ecosystems. Many species of plants, animals, and microorganisms might not have enough time to adapt to the new climate and might become extinct.

Task: Global Mean Temperatures

As a research scientist for the U.S. Panel on Global Climate Change Research, you and your colleagues have been collecting data in the field for months. You have studied research on varying aspects of Earth’s diverse ecosystems, and your colleagues are now gathering to share their experiences and preliminary findings with the rest of the group.

With a major international conference looming, it’s time for all of you to analyze the data and formulate a comprehensive report on global climate change on planet Earth. This conference requires more than a standard report citing data and displaying results in tables and graphs. Analysis of the data will be required to present an accurate picture of the state of the planet’s climate and trends that have been the focus of heated controversy and debate for the last decade. As a scientist, you naturally look at the data from purely objective perspectives.

Given the ongoing controversy surrounding the recorded rise in Earth’s global mean temperatures, your team will have to provide some concrete analysis of temperature data for the report.

Remember: There are quite a few research teams analyzing different global climate change indicators. Your indicator, global mean temperatures, will be an important component to the overall climate change picture.

In order to present accurate, complete, and valid findings, answer the following questions or follow the instructions:

1) Analyze data and identify any trend that occurred in global mean temperatures.

Think “before and after” to help you identify a big picture of Earth's temperature and the changes that may have occurred over decades.

2) What are the impacts of this change? Remember to report the impacts to humans, wildlife, ecosystems, etc.

Changes in environmental temperatures have long-reaching impact and might be slow to develop. This doesn’t mean they are not significant. Look at the long-range effects. The International Panel on Climate Change will need to know impending impacts in order to plan for the future.

3) What appears to be the source(s) of the changes? Can you identify a major cause?

Identifying the cause or source of the changes is important for finding possible ways to remediate the impacts.

4) What strategies do you see that could mitigate or lessen the change? How long would they take to make a difference? What are the pros and cons of the approach?

Sample Rubrics

The developing rubrics page in the Problem Based Learning section provides a content-specific rubric for the Global Temperatures module under the Sample Rubrics heading.

Skill Building Activities

The following activity can be used to help your students learn how they can use NASA satellite data resources to solve the problem-based learning task presented.

Title: Is Grandpa Right, Were Winters Colder When He Was a Boy?

Estimated Time for Completing Activity: 50 minutes

Learning outcomes for this activity:

Students will:

• Access NOAA and NASA climate data from Internet resources.

• Determine changes in average temperatures, precipitation, and cloud cover over time from data.

• Relate global changes to local changes.

Learning Objectives

Alignment of Learning Objectives and Standards
-Temperature as a Key Indicator