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An introduction to the issue of atmospheric ozone layer depletion

Global Warming and Ozone Layer Depletion: Strong, and Peter A. She had just been looking at the record of average surface temperatures of the Earth. The year 1998 was the warmest since reliable temperature records have been kept, and the twentieth year in a row in which the average global surface temperature was higher than the 119-year average.

The next year, 1999, was the fifth warmest on record; the six warmest years on record have occurred in the last decade. And yet, as the class studied the issue further, we learned that the news is not all bad. The nations of the world have already taken collective action to solve one global atmospheric problem: Global warming, as we will discuss below, is a different and a bigger problem, but scientists have already come together to measure, understand the causes of, and set goals for reducing the rate at which it occurs.

The preservice teacher quoted above was attending our college course on the value of Science-Technology-Society STS education for middle and upper elementary students.

The STS movement, as it was advanced during the 1980s largely due to Project Synthesischallenged social studies teachers to prepare students to be scientifically literate as well as socially conscious. This information has been synthesized from comprehensive analyses published by scientists working together in large collaborations, and from works by the authors.

Electromagnetic energy coming from the sun is absorbed by the Earth, which radiates some of this energy outward as infrared energy heat. Greenhouse gases, including water vapor H2Ocarbon dioxide CO2methane CH4and nitrous oxide N2Oare produced as part of the natural system for example, CO2 and H2O are by-products of respiration and combustion.

These gases act much like the glass roof of a greenhouse, letting sunlight through, but keeping heat locked in. Since the Industrial Revolution, humans have developed technologies for example, motor vehicles that produce large quantities of greenhouse gases. Also, humans have invented new molecules that are greenhouse gases, for example, chlorofluorocarbons CFCs and some CFC-substitutes that are used as coolants and solvents. Tree rings, pieces of old coral, and cores taken from glaciers and from mud at the bottom of the ocean provide scientists with samples of atmospheric changes that go back 150,000 years.

This increase in CO2 comes largely from the burning of fossil fuels coal, oil, and natural gas in automobiles and electrical power plants. Most atmospheric scientists are now convinced that human industrial activity has caused an enhanced greenhouse effect, leading to an increase in global warming: To complicate matters, some scientists even speculate that the effects of global warming may perturb ocean circulation patterns so much as to throw us into another ice age.

Depletion of the Ozone Layer An ozone molecule O3 is composed of three atoms of oxygen. Exposure to too much UV radiation is linked to skin cancer, cataracts, and depression of the immune system, and may reduce the productivity of certain crops. The ozone layer is reduced when man-made CFC molecules comprised of chlorine, fluorine, and carbon reach the stratosphere and are broken apart by short-wave energy from the sun. Free chlorine atoms then break apart molecules of ozone, creating an introduction to the issue of atmospheric ozone layer depletion hole in the ozone layer.

Their manufacture is now banned by an international treaty, the Montreal Protocol, signed by 160 nations. But because CFCs have a long atmospheric lifetime about 50 yearsthose manufactured in the 1970s continue to damage the ozone layer today. The amount of CFCs in the stratosphere is now peaking. When the ozone hole was first detected, there was emotional debate in which many U.

It took a few years for scientists to show conclusively that human activity was causing the damage. It did not take long for scientists to invent other chemicals that could replace CFCs for industrial and commercial purposes, but would not harm the ozone layer. CFCs used as propellants were first banned in the United States in 1978. Thus, inclusion of STS issues in social studies instruction links what students are learning in social studies and science classes, providing an interdisciplinary focus.

Americans will face important decisions as consumers, voters, and global citizens. Ideas for the Classroom Applying scientific knowledge and taking citizen actions toward solving societal problems are integral to social studies education.

The STS Investigation and Action instructional model sets forth four categories of citizenship actions: Introductory and investigative lessons provide prerequisite knowledge for citizenship actions.

Each lesson includes social studies and science concepts as well as activities for investigating relationships between the concepts. For example, students use colored transparency film and painted cans to learn about the transmission, absorption, and reflection of light energy. Several lessons in the STS unit on climate change are designed to help students appreciate the relationship between acquiring an introduction to the issue of atmospheric ozone layer depletion and using it to resolve problems that affect society.

Further, opportunities for action provide good creative outlets for students. To help them understand the model, students can decorate the bottles with magazine images to represent different sources of CO2. In the coming years, there will likely be debates in the U. Congress about what might be the best ways to slow global warming.

Banning a single chemical, as was done for CFCs, will not be adequate. Agriculture, manufacturing, power generation, and transportation are a few of the human activities that could be affected by policies to reduce global warming. Without taking sides, a social studies teacher can present some of the opposing viewpoints to the class while also listing the possible costs, benefits, and risks of various policy proposals.

Critical thinking will be called for. Who are the major figures in these debates?

Is There a Connection Between the Ozone Hole and Global Warming?

What interests do they represent? What sources of information do they cite? With a basic introduction to some of the atmospheric science, students should be able to follow much of this news and get involved if they wish.

We will all be affected by the outcome. Finally, teacher modeling of responsible citizenship actions is another suggestion for social studies instruction that emerges from research on elementary teachers. National Oceanic and Atmospheric Administration, 2000. Our unit of study on global climate change is online at www.

National Science Teachers Association, 1982 ; Project Synthesis was an initiative of the National Science Foundation in the late 1970s in which experts critically examined the state of science education. Recommendations for the ideal state of science education were set forth in four goals: Cambridge University Press, 1996 ; J. Mackenzie, Our Changing Planet: Prentice Hall, 1998 ; J. National Academy Press, an introduction to the issue of atmospheric ozone layer depletion.

World Meterological Organization, 1995 ; P. National Science Teachers Association, 1993 7: Borza, Global Atmospheric Change: Pennsylvania State University, 1995 ; See also note 2. This article was originally submitted to the Elementary department of Social Education, whose editor is Mary Haas. The IPCC also sets goals for developed and developing countries to meet for reducing the industrial production of greenhouse gases.

The IPCC is an interesting experiment in international and scientific consensus building and government cooperation. Watch the news for congressional debates about whether the IPCC goals are fair and how nations might best achieve them. For example, one can view a graph that tracks the size of the Antarctic ozone hole from 1979 to 2000, or a recent color image of it. By international agreement, such sprays are no longer manufactured.

The real concern is that CFCs from old refrigerators and air conditioners be properly disposed of, rather than continuing to leak CFCs into the atmosphere. Another misconception is that ozone layer depletion causes global warming by letting in extra solar radiation.

This idea connects two issues global warming and depletion of ozone in the upper atmosphere inappropriately, which diverts attention from the main cause of global warming: These misconceptions may be reinforced by the popular press and are not limited to children: Therein, atmospheric scientists report that the average surface temperature of Earth has increased by approximately 0.

The IPCC now predicts that the average global temperature will increase by 1. An increase of a few degrees Centigrade may not sound like much, but it probably would accelerate the retreat of glaciers and ice caps. Sea level could rise enough to flood coastal cities, especially if temperature increases are sustained beyond the next century. The implications of these findings for society and public policy are great.