Earth Science: Geology, the Environment, and the Universe

Unit 7: Resources and the Environment

WebQuest Projects 1

Is Global Warming Beyond Our Control?


The Earth's atmosphere is a complex, dynamic system. Weather conditions affect everything from how we travel on a daily basis to the food that can be produced worldwide each year. For millions of years of Earth history, natural cycles of warming and cooling affected Earth organisms in important ways, about which scientists can only speculate. But what about human impact on the atmosphere? Do humans play a role in climate change? Natural atmospheric cycles have occurred for millions of years. Is it possible that human activities over the last 250 years could significantly impact such an established, large, and complicated system?

The Industrial Revolution, which began in Great Britain in the mid-1700s was a watershed event in human interaction with the atmosphere. As fossil fuels were burned in increasingly greater amounts, the amount of carbon dioxide released into the atmosphere rose significantly. Industrialization and population growth continue today. At what cost? While the topic is hotly debated in the scientific community, scientists agree on several points. Atmospheric concentration of carbon dioxide and other greenhouse gases is increasing at an unprecedented rate, there is a direct connection between the concentration of carbon dioxide in Earth's atmosphere and the average surface temperature, and the average temperature at the Earth's surface currently is increasing. However, there is great debate on how much is a result of human activity. Throughout Earth's history, climate change has been driven by natural processes and events rather than by human activity. Is that still the case?


As you complete this WebQuest, you will investigate the nature of the connection between the combustion of fossil fuels, the production of greenhouse gases, and the global warming trend the Earth currently is experiencing. You will conduct internet research to answer questions about the greenhouse effect and changes in Earth's atmosphere and climate. You will review and analyze graphed data at specific Web sites showing how carbon dioxide, global surface mean temperature, and Arctic sea ice have changed throughout Earth's recent and extended history. Finally, based on your evaluation of the information gathered, you will form and write an opinion about the extent of the role humans play in global climate change.


The Web sites given here will help you answer questions about global climate change and how it is measured. The information you gather will help you form an opinion about the level of importance of human activities to the current global warming trend.
The article at this site describes how the level of atmospheric carbon dioxide is changing over time. A forecast from the Intergovernmental Panel on Climate Change is given for atmospheric CO2 level and average global temperature change by the year 2100. Be sure to visit the interactive global warming features at this site, which give graphed data regarding CO2 emissions worldwide, a description of the greenhouse effect, and a history of global warming over the last 20,000 years.
Visit this site to find answers to frequently asked questions about global warming. Questions include "Is the climate warming?" and "Can observed changes be explained by natural variability?" Links within the answers provide graphed data and additional related information.
The article at this site explains the process of global warming, and describes specific human activities that are altering the composition of Earth's atmosphere.
The paleoclimate record shows that rapid and dramatic climate changes have occurred throughout Earth's history. Visit this site to learn what scientists know and don't know about what caused these changes, as well as how Earth's climate was affected by them.
This site is based on a timeline which describes Earth's climate history for periods ranging from current to more than 100,000 years ago. Visit this site to learn about natural cycles of climate change over time, and the factors that may cause these cycles to occur.
Visit this site to learn about abrupt climate change through answers to a series of frequently asked questions. Questions include "Have humans contributed to global warming?" and "Can global warming cause an Ice Age?"
The article at this site explains how scientists use a wide variety of information to understand past climate change and predict future trends. Graphs showing estimates of mean surface air temperature, as recently as the last 1000 years and as distant as the last 100 million years, are provided.
This site explains how Earth's climate changed abruptly during a period in Earth's history known as the Younger Dryas. The article found here relates long-term global warming to possible rapid cooling of the climate.
The article at this Web site explains how scientists use ice cores to learn how Earth's climate has changed over the last 200,000 years.
This site gives a chronology that outlines the history of weather data collection in the United States.
The article at this site addresses changes in global climate that began 8000 years ago. Visit this site to learn about a new theory connecting the development of farmlands in Asia and Europe to increases in atmospheric CO2 and methane thousands of years ago.


1 week to answer the questions, analyze the graphs, and write an opinion


Read the following series of questions before beginning your research. As you explore each Web site, look for answers to the questions.

Questions about Global Climate Change
  1. The greenhouse effect is a natural atmospheric process that has a tremendous impact on Earth. Describe this process, including what causes it, the factors that influence it, and how it affects Earth.
  2. Identify the major greenhouse gases found in Earth's atmosphere.
  3. While the term greenhouse effect often has a negative connotation when used in the media, the process is crucial to life on Earth. Explain why.
  4. Compare the levels of atmospheric carbon dioxide just prior to the beginning of the industrial age in the mid-1700s and in 2004.
  5. Changes in the concentration of greenhouse gases can cause changes in Earth's average surface temperature. What other natural factors or events also can cause long-term changes in surface temperature?
  6. How long have consistent weather measurements been collected and recorded throughout the United States?
  7. Atmospheric composition and conditions are different today than at other times in Earth's history. What types of things do scientists examine to learn what the atmosphere was like hundreds, thousands, or even hundreds of thousands of years in the past? Specifically, explain how a history of climate can be reconstructed from an ice core.
  8. Analysis of air pockets in glacial ice show that an abrupt climate change took place about 12,000 years ago. The discovery of this period, named Younger Dryas, has changed scientific thinking about the length of time required for global climate change. Describe the Younger Dryas period, including how it could be related to a past global warming trend.
Next, visit the Web sites listed below. Use information from your research to answer the questions. As you study the sites, remember that you will use the information you gather to write your opinion about the extent to which human activities affect global climate change. Your written opinion should include specific information that supports your view.

Scientists collect data about global change through both direct and indirect measurements. Graphed data often shows trends and patterns that can help researchers evaluate past changes in climate and make predictions about future climate changes. Study each of the six graphs shown at the Web sites listed below, then write a brief analysis of the data shown by each graph. Your analysis should include a description of the variables shown on the graph and a summary of any trends or patterns you observe. Consider copying and printing each graph, then making notes and writing your analysis directly on the page that shows the graphed data.

Graphs to analyze
Carbon dioxide concentration, as measured at Mauna Loa, Hawaii, from 1955 to the present
Atmospheric concentration of carbon dioxide and methane and Antarctic temperature, from 420,000 years ago until prior to the Industrial Revolution
Global surface mean temperature anomalies from 1880 to the present
Reconstructed annual northern hemisphere mean temperature from 1400 to 2000
Estimate of Earth's mean surface temperature for the last 800,000 years
Arctic sea ice extent anomalies from 1973 to 2000

Finally, write your opinion which answers the following question: "Is human activity responsible for the current global warming trend affecting the Earth?" Your written opinion does not need to be lengthy, but should include details from your research that support your point of view. Be prepared to defend your opinion during discussion with your classmates and teacher.


While completing this WebQuest, you have learned about the greenhouse effect and its importance to life on Earth. You have examined various factors that can cause changes in Earth's surface temperature, including changes in atmospheric concentration of greenhouse gases. You have analyzed graphs showing how surface temperature and atmospheric carbon dioxide concentration have changed during Earth's recent and extended past, and have learned how scientists estimate these measurements when they cannot be made directly. Based on your research, you have written an opinion about the dominant cause of the recent global warming trend. In developing your view, you have recognized that while scientists agree that the Earth's mean surface temperature is increasing, they do not all agree on the extent of the role played by the burning of fossil fuels in global warming. Forming an opinion supported by data, and recognizing the validity of differing opinions, also supported by data, are crucial skills in science and in many real-world tasks.

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