This unit will introduce high school students taking Environmental Science or Earth and Space Science to the history of Global warming. It begins with an examination of climatic fluctuations of the planet over the last 770 million years in order to show that climate changes, and often does so radically and quickly.

This will be followed by defining what the greenhouse effect is in broad terms. Finally students will examine the recent history of the science and politics behind global warming. Both sides of the debate will be critically examined as well as the implications for each position.

There is little doubt that of the many environmental issues challenging humanity, that of Global Warming is the one most often seen reported in the news. Numerous conferences, national organizations, and international organizations provide new releases to the media on a weekly basis.

Those who read these reports are subject to a very one sided view of the issue with little space given to opposing views. Science is based on vigorous debate where all sides of an issue are examined under a microscope. This lack of an airing of the debate on global warming robs citizens of the knowledge needed to make critical decisions regarding their future and that of the planet.

In this unit, high school students will study the history of the climate of earth and see how the debate on global warming fits into the larger scheme of things. This unit will serve as an adjunct to Chapter 31, Climate and Climate Change, in the Pittsburgh School district text for 11^th/12^th grade Earth and Space science.

The Geologic History of the Climate

Dramatic changes in the earth’s climate is a normal state for our planet. Recent geologic discoveries underscores this basic fact. 770 million years ago a single continent broke apart into smaller continents due to plate tectonics. The result of this break up was to expose formerly landlocked areas to oceanic sources of moisture.

Our planet has a thermostat, found within the carbon cycle, that controls the temperature of the planet. During the breakup of this continent, increased rainfall from the oceans scrubbed carbon dioxide out of the atmosphere. The rain combined with atmospheric carbon dioxide to form carbonic acid which reacted with exposed rocks, weathering them and carrying the products into the ocean. Here the weathered material precipitated out into carbonate rocks, locking up the carbon dioxide for millions of years.

Global temperatures fell and ice packs started to form in the oceans and glaciers appeared above the snowline of mountains. The ice reflected more solar energy than the dark ocean water causing a further drop in temperatures. This feedback cycle triggered a planet wide cooling that resulted in "snowball earth."

On this snowball earth temperatures drop to –50 degrees Celsius and the oceans are frozen to a depth of a kilometer. The air is so cold that no moisture exists in it, stopping the growth of glaciers. However, without moisture there is no rainfall, allowing the carbon dioxide from erupting volcanoes to gradually build up over 10 million years. The 1,000 fold buildup of carbon dioxide triggers a rapid warming of the planet.

Increased warming increase the amount of water vapor in the atmosphere due to evaporation. This acts to intensify the greenhouse conditions until the surface temperature reach an average of 50 degrees Celsius. Torrential rains on this hothouse earth wash the carbon dioxide out of the atmosphere, forming carbonic acid, which weather the exposed rocks. The cycle begins again.

How often did our planet suffer these extremes in climatic conditions? Possibly as many as four times between 750 and 580 million years ago.

At the end of this period the planet settled down into a warmer pattern conducive to the development of a multitude of new species of multi-cellular life forms. 570 million years ago, the Paleozoic Era began, and lasted 320 million years, until a great extinction of some sort destroyed 90 % of all life on the planet. Climatic change continued, with great drying outs, ice ages, and the advance and retreats of the ocean into great shallow seas.

It was during one period of this era that the great deposits of coal, oil, and natural gas was laid down. This was the Pennsylvanian period, during which, much of the worlds land masses were located near the equator. The conditions were right for the formation of massive swamps and warm shallow seas.

The beginning of the Mesozoic Era, 250 million years ago, was marked by the break up of the super continent Pangaea. All the modern continents were located close to the equator at this time surrounded by warm seas. The climate during this period of time was mild with ice-free poles. The temperature was 10 to 20 degrees Celsius warmer than it is now (fig. 1).

For 185 million years dinosaurs ruled the planet. At the end of this period a massive environmental disaster struck, radically changing the climate. The first change in climate was a consequence of the break up of Pangaea. Like before, more land mass was exposed to marine moisture increasing rainfall across the planet. This rainfall reduced the amount of carbon dioxide causing a gradual drop in temperature. Ice began to form and ocean levels dropped.

At this time the crisis was exacerbated by the arrival of a 10-kilometer asteroid that struck the planet in the vicinity of the Yucatan peninsula. A huge cloud of debris was carried up into the atmosphere blocking out light and rapidly dropping the temperature of the planet. Within this cloud of debris was an aerosol of sulfuric acid caused by the vaporization of a massive bed of gypsum coincidentally located right where the asteroid struck.

Scientists have since discovered that sulfuric acid aerosols are extraordinarily effective in blocking out incoming solar radiation. Temperatures on the planet dropped further. At the same time the huge quantities of ocean water that was vaporized began falling as torrential rains washing more carbon dioxide out of the atmosphere just when the planet could least afford the loss of greenhouse gases.

Meanwhile, on the far side of the planet in India, massive volcanic eruptions began in an area now know as the Deccan Traps. Evidence indicates that massive eruptions propelled huge quantities of more sun blocking dust and sulfuric acid aerosols into the atmosphere. There is some thought that the shock of the asteroid strike may have caused these eruptions.

In the last 65 million years the planet has not been as warm as it was during the Mesozoic. In fact, during the last million years the planets temperature has been so low that there have been repeated episodes of mass glaciation. This trend extends to the present where the present epoch, the Holocene, is considered an interglacial period. An interglacial period is considered a period of temporary warming between extended periods of glaciation.

Figure 1 A schematic reconstruction (solid line) of mean global surface temperature through the last 100 million years, based on analyses of various marine and terrestrial deposits. The dashed-line extension is a prediction of future trends through the coming 400 years, based on the assumption of substantial utilization of the fossil fuel reservoir. The vertical line shows the approximate range of surface temperature in climate model predictions for a doubling of CO₂ levels, at about 100 years in the future. Modified from T. J. Crowley, Journal of Climate, vol 3, pp 1282-1292, 1990.

During the last million years, the ice advanced and retreated four times. The last advance ended 11, 000 years ago. During the past 160,000 years, temperatures were, on average, 3 degrees Celsius cooler than they are now (fig.2). What is the cause of this drop in temperature?

One explanation for the cause of ice ages is called the Milankovich cycle. In this cycle there are times when the incoming solar radiation (insolation) is reduced due to the earth’s orbit being more elongated, which carries the planet farther from the sun than normal. At the same time, the earth’s axis is titled farther over, which also reduces the amount of heat from the sun. Lastly, the solar cycle is at a low, such that the sun is giving off less heat than normal. The combination of these three cycles, when they align, result in a general cooling of the planet.

· 21,000 year cycle: Elliptical orbit of the earth around the sun

· 41,000 year cycle: Cycle of the +/- 1.5 degree wobble in the          earth's orbit

· 100,000 year cycle: Variations in solar energy input

The late Cenozoic was also marked by widespread volcanic eruptions which would have introduced dust and sulfuric acid aerosols into the atmosphere. Both of which would have reduced insolation. This was also a time when numerous mountain ranges were being uplifted. When this occurs, weathering increases due to the steepness of the land and the increased exposure of rocks. This in turn increases the amount of carbon dioxide locked away as carbonate rocks.

Since the end of the last ice age, levels of carbon dioxide have been increasing steadily. This has resulted in the surface of the planet changing from being predominantly frozen wastelands and deserts to a surface dominated by forests and grasslands. During this period, the maximum average temperature of the planet was reached during the Holocene maximum (fig. 3). This occurred between 7,500 and 4000 years ago with a temperature 1 degree Celsius above today’s average.

Figure 2 Air temperature near Antarctica for the last 150,000 years. Temperatures given are inferred from hydrogen/deuterium ratios measured in an ice core from the Antarctic Vostok station, with reference to the value for 1900. Compiled by R. S. Bradley and J. A. Eddy based on J. Jouzel et al., Nature vol 329, pp 403-408, 1987 and published in EarthQuest, vol 5, no 1, 1991.

Figure 3 Variations in regional surface temperatures for the last 18,000 years, estimated from a variety of sources. Shown are changes in ° </°>C, from the value for 1900. Compiled by R. S. Bradley and J. A. Eddy based on J. T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge University Press, Cambridge, 1990 and published in EarthQuest, vol 5, no 1, 1991.

The first centuries of this millennium saw a period of especially mild temperatures that may have reached their maximum during the 12^th and 13^th centuries. This was the so-called "Medieval Warm Period." This period was followed by the "Little Ice Age" in which average global temperatures dropped by 0.5 to 1 degree Celsius (fig. 4). The consequences of this drop was the advance of alpine glaciers and harsh winters that froze many rivers solid.

The Little Ice Age is considered to have stopped between 1840 and 1860. Since then the planet has grown warmer. This point in history is also recognized as the beginning of the Industrial Revolution in which man learned to use the energy trapped in fossil fuels to power industry.

It can be seen from the history of our planet that climatic change has happened often. The changes are dramatic and often results in massive extinction's due to changes in habitats. Recent evidence from ice cores also indicate that massive changes can occur in a relatively short span of time. Perhaps within 50 years, the life span to a typical human.

The question facing mankind now is are we facing a major climatic change, and, if so, what is the cause? Popular press presents the case that human activity has caused a massive buildup of CO2 in the atmosphere. This buildup is causing a global increase in temperatures due to the "Greenhouse Effect."

Figure 4 Example of regional variations in surface air temperature for the last 1000 years, estimated from a variety of sources, including temperature-sensitive tree growth indices and written records of various kinds, largely from western Europe and eastern North America. Shown are changes in regional temperature in ° </°>C, from the baseline value for 1900. Compiled by R. S. Bradley and J. A. Eddy based on J. T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge UniversityPress, Cambridge, 1990 and published in EarthQuest, vol 5, no 1, 1991.

The Greenhouse Effect

Our planet receives most of its heat energy from the sun. It arrives here mainly as radiation in the visible light spectrum. As this light enters the atmosphere it is referred to as "Incoming Solar Radiation" or Insolation. Some of this insolation will be reflected back into space by high clouds in the atmosphere. Some will be absorbed by the atmosphere and lower clouds.

However, most will reach the surface of the planet and warm it. Heat absorbed from the visible light will warm the ground, which will then re-emit the energy as infra-red radiation which further warms the lower atmosphere.

Greenhouse gases such as Methane, Water Vapor, and CO2 allow the visible light to pass through the atmosphere and warm the surface. However, these same gases block infrared radiation from passing out of the atmosphere. The heat is held in and the atmosphere is warmed. If it were not for these gases, our planets temperature would average –16 degrees C.

History of Global Warming

1827- Jean Fourier, a French mathematician and physicist determined that heat from the sun absorbed by the earth was reflected back to the earth by the atmosphere. He identified Carbon Dioxide as the reflective gas and coined the term "Greenhouse Effect."

1860- John Tyndall, an English scientist, isolated Carbon Dioxide and water vapor as the two most important heat absorbers in the atmosphere, with water vapor being the more powerful of the two.

1896- Svante Arrhenius, a Swedish chemist, proposes that changes in the amount of Carbon Dioxide in the atmosphere could be responsible for the coming and goings of ice ages. He calculated the impact of doubling the amount of carbon dioxide in the atmosphere and came up with an increase in global temperatures of 5 to 6 degrees Celsius (twice today’s estimate). He went on to estimate how long it would take this doubling to take place based on the existing rate of coal burning. This was the first time anyone had linked burning fossil fuels with climate change. The results of his math was 3,000 years to double amount of carbon dioxide in the atmosphere.

1938- G. S. Callendar, an English meteorologist, tried to convince the Royal Society that Global Warming had started. He used data from 200 weather stations world wide to show that average temperatures had increased between 1880 and 1930 by 1/2 a degree Celsius. He further estimated that is would rise 2 degrees Celsius over the next century. He saw no harm in this and thought it would improve plant growth and delay the return of the glaciers.

1950’s- Global temperatures begin to cool slightly

1957- Roger Revelle, an American scientist, discovers that the oceans are not absorbing as much carbon dioxide as originally thought. Stated "human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future."

1958- Roger Revelle and Charles Keeting establish the Manua Loa observatory for taking carbon dioxide readings far from any contamination. After two years of readings a clear trend is seen in increasing levels of carbon dioxide. Plotted on a graph, the curve, called a Keeting curve, showed seasonal changes in carbon dioxide as plants absorb it in the summer and its released by decaying vegetation in fall and winter. The graph shows a steady saw-toothed curve upwards each year to the presence.

1965- White House orders study to see if burning fossil fuel increases carbon dioxide in the atmosphere.

1988- Toronto Conference held. Goals are set to cut carbon dioxide emissions by 20 % by 2005 and reduce deforestation. A goal of establishing a world atmosphere fund supported by a levy on fossil fuel consumption by developed countries (carbon tax). The South Pacific forum held consisting of island countries threatened by rising sea levels.

1992- Earth summit at Rio de Janeiro. North wants forests preserved as carbon sinks while South consider lumber on of their major economic resources. Issue of the loss of biological diversity tied to global warming. Estimates are that 50,000 species per year are becoming extinct due to climatic stress.

1997- Kyoto Protocol. Industrial nations agree to reduce average greenhouse emissions to 5 % below 1990 emissions beginning 2012. United States signed the protocol but the senate did not ratify.

What are the Greenhouse Gases?

Carbon Dioxide is the most commonly discussed of the greenhouse gases and, as such, the most widely recognized by the layman. It is a natural product that arises from respiration, decay of land plants, and volcanic activity. Of the estimated 186 billion tons of CO2 that enters the atmosphere each year from all sources, 6 billion tons come from human activity, 90 billion tons come from biological activity in the earth’s oceans, and the remaining 90 billion tons come from volcanoes and decaying land plants.

This human activity includes simple respiration and the burning of fossil fuels. It is the burning of the fossil fuels that concerns environmentalists. Interestingly, another by product of burning fossil fuels is sulfur dioxide. This reacts with rain to form acid rain. It has turned out that models for increases in temperatures due to global warming have been off by a considerable amount due to the present of this gas in the industrial countries.

Sulfur dioxide is an incredibly effective sun block. When Mt. Pinatubo erupted in 1991, 20 million tons of sulfur dioxide was blown into the troposphere. The consequence was a global drop in temperature due to a 2% reduction in solar radiation. Average worldwide temperatures dropped 1/4 degree C. for two years.

Since the beginning of the industrial revolution, CO2 has increased by 27% in the atmosphere. This works out to about 360 parts per million or less than 4/100ths of 1% of all gases present .

It is known that there has been a 27% increase of CO2 in the last 200 years in the atmosphere. The question is, how much is due to man and how much is due to nature? It does appear that there is some correlation between the amount of solar activity and the amount of CO2 in the atmosphere. Whatever the cause, it is estimated that this additional CO2 may last 50-200 years in the atmosphere.

Methane is another of the greenhouse gases and is 20 times more efficient than CO2 at trapping heat. Since 1750, amount of methane in the atmosphere has more than doubled. Methane by itself is responsible for 15-20% of the heat up of the atmosphere and lasts 12-17 years in the atmosphere.

Quantifying its source is a bit more difficult than for CO2. It is generated in landfills, rice paddies, and from natural gas. It is also generated by animals who are ruminants, such as cows, every time they chew their cuds. As population grows, people will raise more cows and more rice, increasing the sources of methane. However, an estimated 1/5^th of methane comes from a source that is hard to control, termite flatulence.

The plus side of methane is its short life span in the atmosphere. However, of great concern is the methane stored in the permafrost of the arctic and locked in massive undersea beds. A slight warming of the permafrost may release methane locked up as methane hydrates in tremendous quantities. 1 cubic meter of permafrost may contain 160 cubic meters of methane. This suggests a very disturbing scenario of a runaway greenhouse effect in which the warmer it gets, the more permafrost is melted releasing more methane, making it warmer…. And so on.

Another gas is Nitrous Oxide. This produced by automobiles and natural ocean processes. There has been a slight 13% increase in the last 200 years and is survives 125 years in the atmosphere.

This overlooked gas may become more significant in the future. Scientist believed that the oceans produced about 2 million tons of it per year from deep water sources. In 1998, scientist discovered it being produced in much shallower waters and tripled their estimate to 6 million tons of year going into the atmosphere. What concerns them is that El Nino activity could increase this quantity even more by disturbing deep Pacific waters. Some scientist see a relation between increased numbers of El Nino events and global warming.

As mentioned, the most common of the greenhouse gases is water vapor. It presents a quandary to those attempting to model the climate and what is happening to it. For water vapor condensed as high clouds reduces insolation, and so cools the planet down. Water vapor condensed as low clouds reduces radiation, and so warms the planet up. As the planet warms up, more water evaporates which means more cloud cover. The question is unresolved on how this increase in cloud cover will affect the climate.

Consequences of Global Warming

Most of the increase in warming of the planet due to the greenhouse effect will occur between the 40 degrees and 70 degrees north. This will reduce the difference between night and day temperatures as a result of increased cloud cover keeping the nights warmer. This would cause more heat related deaths due to heat stroke and salmonella. Shifting climate zones northward would also introduce tropical diseases into areas previously free of them.

This will also increase the amount of melting of glaciers with the possible consequence of rising sea levels. These sea levels may also rise due to thermal expansion of warm water. In the south pacific this thermal expansion near the equator actually raises the sea level 1 meter. This has been a trend over the last 100 years with an average estimated rise of 1-2.5 mm per year (4-10 inches net gain over the last 100 years).

Some models that have been run show that if the East Antarctic ice sheet were to melt, the level of the oceans would rise a catastrophic 200 feet. Fortunately this is very unlikely even with the worst case scenarios. More possible would be the melting of the west Antarctic ice sheet. In this case the oceans would rise 13-23 feet.

The impact of one projected rise in sea level of 20 inches by 2100 would be the loss of many island nations. The AOSIS (Association of Small Island States) fear they will have their islands rendered largely uninhabitable by 2050 due to wave erosion of coasts, saltwater intrusion into aquifers, and sinking land due to extraction of groundwater.

Additional rises in sea level to 36 inches would put 1/3 of the worlds crop growing areas at risk, as well as the homes of 1 billion people. This potentially could create up to 50 million environmental refugees.

One of the major areas of study in regards to global warming is what will happen to the Gulf Stream. This warm current of ocean water is what keeps Northern Europe inhabitable. Carrying water warmed in the tropics up the east coast of North America and then across the Atlantic to Europe, it keeps Europe from having a climate like northern Canada.

If excess fresh water is released into the north Atlantic from the Arctic, the Gulf Stream will cease to flow as it does. Paradoxically Europe may freeze as a result of global warming, with weather like Siberia putting millions of people in danger.

This increase in CO2 may have a positive effect as well. One is the increase in plant growth which may result in huge production increases in crops. As the warm climate moves north, large parts of Canada and Russia will become viable for agriculture as well as extending the growing season of the existing agricultural areas.

Back in the 1970’s there was a very real concern that we were headed back into another ice age. As shown before, we are at the end of an interglacial period and due for a drop in global temperatures triggering another ice age. One scientist has proposed that our unintended modification of the atmosphere may be the greatest benefit that came out of the industrial revolution.

Students will be able to:

1. Understand the cyclical changes of the climate over the previous 800 million years.

2. Identify natural causes for climatic variation.

3. List the major historical events leading to the present concept of global warming.

4. Explain how the greenhouse effect works.

5. Identify the major greenhouse gases and their natural and manmade sources.

6. List possible consequences of global warming on the planet and humanity.

7. Use available research to examine both sides of the debate on whether global warming is occurring.

8. Use available research to examine both sides of the debate on causes of global warming.

Students will be given a series of lectures using the material provided in the rationales section to give them the background material needed for the learning objectives. Interspersed between lecture sections, classroom activities and assignments will be given. These will include hands on labs and written assignments. The unit will culminate with the students forming committees in order to formulate strategies for Pittsburgh to use to meet the potential challenge of global warming. These committees will also propose ideas for people to use to combat the causes of global warming.

Activity one: Students will be given a writing assignment before the unit begins which will require them to interview a parent or grandparent. In this interview students will ask the following questions; Was it colder in the winter when you were my age?

Did it snow more in the winter?

Was it hotter in the summer?

Was it dryer or wetter in the summer?

What is your most vivid weather memory?

Did you pay much attention to the weather?

How did weather affect the way you lived?

Activity two: Students will construct a timeline using data tape. Students will develop a scale for the timeline, (for example one centimeter equals 1 million years) and plot the major climatic events provided to them in the first lecture on the climatic history of the earth. Students will illustrate the major climate change points with appropriate pictures on their timeline.
Materials needed; One 7 meter length of tape per two students

One meter stick per two students

One box of colored pencils per two students

Activity three: Students will construct a bar graph using the following data set for the ten warmest years between 1880 and 1992, in degrees Fahrenheit.

1973;59.31 1977;59.30 1980;59.51 1981;59.64 1983;59.51

1986;59.30 1987;59.56 1988;59.64 1989;59.45 1990;59.81

Students will answer the following questions;

During which year was the average world wide temperatures highest?

Is there a warming trend indicated by this graph?

Is there a steady climb in temperatures shown in this graph?

Develop three additional questions you would ask before deciding whether this

was proof for or against global warming.

Activity four: Students will construct a line graph using the following data set of average temperatures for Pittsburgh. July, being the hottest month will be plotted every ten years, starting in 1900 in degrees Fahrenheit.

1900;73.4 1910;72 1920;68.9 1930;73 1940;71.3 1950;68.1

1960;68.2 1970;70.6 1980;70.4 1990;69.9 2000;69.2

During which year was Pittsburgh the warmest?

Is there a warming trend indicated by this graph?

Is there a steady climb in temperatures shown in this graph?

Develop three additional questions you would ask before deciding whether this was proof for or against global warming.

Activity six: Students will conduct a self energy audit in order to determine how much carbon dioxide their activities add to the atmosphere

Problem 1: 1 gallon of gasoline releases 20 pounds of carbon dioxide in the atmosphere.

Miles per gallon your car gets: _____________ mpg

Miles per day car is driven: _____________ miles

30 days per month x daily miles = __________ miles per month

Miles per month/ mpg = ______________ gallons of gasoline per month

Gallons of gasoline per month x 20 lbs. of CO2 per gallon = ____________ lbs. of CO2 released per month

Problem 2: RE-calculate problem 1 using 54 miles per gallon as your fuel efficiency

Problem 3: Calculate your other energy use rates

Source Usage Pounds of CO2 Total Monthly

Per month emitted/kWh emissions

Electricity _______kwh x 1.5 lbs./kWh ___________ lbs. CO2

Natural Gas _______therms x 12 lbs./therm ___________lbs CO2

Heating Oil _______gal. x 23 lbs./gal. ___________lbs CO2

Gasoline _______gal. x 20 lbs./gal. ___________lbs CO2

Asks students to figure out how they could cut back their CO2 production by 25%. What sacrifices would they have to make?

Activity five: Students will form city planning committees in the areas of health, agriculture, transportation, education, and disaster management. Each committee will develop strategies for the city to use to better prepare for a global warming scenario. They will also propose ideas for ways in which people can combat the causes of global warming.

Reference List

Bilger, Burkhard. Global Warming. New York, Chelsea House Publishers, 1992.

Johnson, Rebecca L. The Greenhouse Effect: Life on a Warmer Planet. Minneapolis: Scerner Publications, 1990.

Oppenhiemer, Michael, and Robert H. Boyle. Dead Heat: The Race Against the Greenhouse Effect. New York: Basic Books, 1990.

Pringle, Lawrence. Global Warming: Assessing the Greenhouse Threat. New York: Arcade Publishing, 1990.

Revkin, Andrew. Global Warming: Understanding the Forecast. New York: Abbeville Press, 1992.

Snow, Theodore P. Global Change. Children’s Press, 1990

Tesar, Jenny. Our Fragile Planet: Global Warming. New York: Facts on File, 1991

Reading list for students

Crowley, Thomas J. Remembrance of things past: Greenhouse Lessons from the Geologic Record. Consequences: Volume 2, Number 1 1996 http://gcrio.ciesin.org/CONSEQUENCES/winter96/geoclimate.htm

(Note: Mr. Crowley was contacted for permission to use the graphs incorporated into the lecture note portion of this unit in May, 2001)

Hoyt, Douglas V. Karl Popper and the IPCC Climate Models. http://users.erols.com/dhoyt1/annex2.htm

Javna, John. 50 Simple Things Kids Can do to Save the Earth. New York: Andrews and McMeel, 1990.

List of Materials for classroom use

30 sets of colored pencils

adding machine tape, 10 rolls

15 meter sticks

Pittsburgh Public Schools Science Standards Addressed

1. All students explain how scientific principles of chemical, physical, and biological phenomena have developed and relate them to real-world situations

2. All students demonstrate knowledge of basic concepts and principles of physical, chemical, biological, and earth sciences

3. All students explain the relationships among science, technology, and society

4. All students evaluate advantages, disadvantages, and ethical implications associated with the impact of science and technology of current and future life

5. All students evaluate the impact on current and future life of the development and use of varied energy forms, natural and synthetic materials, and production and processing of food and other agricultural products