Carbon Cycle Notes:

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Index:

• Greenhouse Effect
• Carbon Cycle
• Historical and Future Predictions
• Global Concerns

Greenhouse Effect:

1. Water Vapor:
1. Predominant greenhouse gas, humans have little control over the amount in the environment.
2. Increased heat results in increased evaporation.  Hotter air holds more water vapor, creates feedback loop so the earth gets warmer.
2. Carbon Dioxide:
1. Humans and natural causes have contributed to the CO₂  in the atmosphere.
2. IPCC (International Panel on Climate change) estimates rising Carbon Dioxide due to fossil emissions accounts for 60% of the global warming since 1850.
3. Carbon Dioxide levels are rising at 0.3% each year (thought to come from human actions).
4. The atmosphere now has 30% more Carbon Dioxide than before the industrial revolution.

1. At the current rate, the atmosphere should contain two times the pre-industrial Carbon Dioxide level by 2060 (see National Geographic, May 1998, Unlocking the Climate Puzzle)
2. A carbon dioxide molecule may last in the atmosphere up to 100 years.
3. Atmospheric carbon dioxide is released from fossil fuel, cattle, cement, burning biomass, as well as other means.
1. Methane:
1. Principal ingredient of natural gas.
2. Generated by bacteria in rice paddies, decomposing garbage, cattle, and ruminant animals.
3. Fossil fuel production, landfills, pipeline breaks, as well as, other means.
4. CH₄ is 2.5 time as prevalent as before the industrial revolution.
5. Each molecule absorbs 20 to 30 times as much radiation as a CO₂   molecule (A more potent greenhouse gas.)
6. Caused an estimated 15% of Global Warming in modern times.
2. CFC's:
1. Are destructive to stratospheric O₃ -- causing a high level hole in the ozone which leads to increased UV radiation.
2. Persists in the atmosphere for centuries.
3. NO2:
1. Agriculture and industry, cars (in effect: the burning of organic materials and soil denitrification).
2. Each molecule has 200 times the heat absorption capacity of  a molecule of CO₂.  (A very potent greenhouse gas.)

1. The little ice age cold snap in 1570 - 1730 (caused European farmers to leave fields) was triggered by only a 0.5 degree Celsius reduction in temperature.

Carbon Cycle:  How does CO₂ fit in?  (or:  "Carbon:  Why is it important?)

1. Two ways Carbon fits in:
1. The geochemical cycle recycles the raw materials that make up all the body structures from hair, muscle, skin.  These are all Carbon based.  (The fundamental unit of all living things.)
2. Carbon forms bonds that store energy to allow all living organisms to think, move, eat, sleep, breathe, repair...
 
1. Possible Pathways:
• A carbon atom may travel a path rapidly like in sugar eaten at breakfast and energy taken as bonds split and exhaled as CO₂ the same day.
                        OR
• A carbon atom may travel a path slowly like in sugar made into body muscle that stays in the body until it decays and CO₂ is released.
                        OR
• A carbon atom is put into a tree (as wood) and when the tree is burned, CO₂ is released (another slowly).
• Carbon can also travel very slowly.  It could be located in a plant which eventually dies.  Over time, the biomass from the plant is buried under sediment and placed under extreme pressure which allows it to eventually form coal.  (Coal can be extracted from the earth as an immediate fuel source by being burned, thus releasing CO₂ into the atmosphere.)
• Carbon could be stored in CaCO₃ made from shells and skeletons of marine animals.
2. Tracing the path of a Carbon atom.
1. The Carbon Cycle begins with CO₂ accumulating in plant sugar molecules created in the process of photosynthesis.  This carbon material is eventually moved into other organisms through the energy web.
2. Atmospheric CO₂ is a source of carbon in the cycle.  It passes into the ecosystem through living organisms.
3. CO₂ is released into the atmosphere weathering, respiration, and combustion.
1. Weathering:  CaCO₃ is in rocks.  When rocks combine with water, carbonic acid is formed and it then splits into carbonate, bicarbonate, and hydrogen ions.
2. Respiration:  sugar + O₂ will produce CO₂ + H₂O.
3. Combustion:   when trees are burned, CO₂ is released.
4. Each carbon molecule has made approximately 30 trips through he carbon cycle in the last 4 billion years (the carbons are constantly being recycled over and over and over).
2. Sources of CO₂:

1. Atmosphere:
1. Burning of fuel wood.
2. Burning of fossil fuels.
3. Burning of peat (organic materials buried in bogs).
4. Cow farts (other ruminants can be included as well)
5. Generation of heat.
6. Generation of electricity.
7. Production of cement.
2. Where CO₂ can "sink" (or be stored for great periods of time).
1. As fossil fuels:  organisms die, fall to the bottom of wetlands/oceans, are compressed by water and sediment.  They first form peat and then coal and or petroluem or natural gas.
1. Coal:
1. from dead plants.
2. U.S. still uses 22% of the world's budget of coal (mostly for generating electricity)
3. Coal (coke) used to run steam engines in industrial revolution for factories.
4. During the Industrial Revolution coal was used to make electricity to run factories and for transportation
2. Petroleum:
1. From dead aquatic microorganisms.
2. Each person in the U.S. uses 200 gallons of petroleum each year.
3. The U.S. consumes 30% of the total global consumption of petroleum.
4. Products:  propane, jet fuel, heating oil,  kerosene, tar.
5. From fossilized remains of aquatic organisms.
3. Natural Gas:
1. From decomposition of all organic material.
2. Most efficient of all fossil fuels at 89% (11% loss to heat) verses 70% energy loss while burning coal.
2. Other sinks of CO_2:
1. Phytoplankton in oceans and ocean itself.
2. Forests.
CO₂ Production
1. More CO₂ is produced each year at an increasing rate of approximately 0.3%.
1. This is thought to be from human actions (anthropogenic).
2. Approximately 85 billion metric tons of CO₂ are released each year.

Historical and Future Predictions:

1. The past 100 years the temperature has increased 0.5 degrees Celsius.
1. Globally, we are now the warmest we have been since 1400 AD.
2. Warming effects are greatest over the mid latitude (Europe/Plains) in winter and spring (hotter and drier for wheat and corn belts).
3. Seasonal differences in CO₂, release more in winter and less in summer (photosynthesis).
2. Effects/Predictions:

1. Frost free season is now eleven days longer than in 1950 in North America (better for food crops).
2. Night temperature increases more than day temperature because the increased gases keep the temperature warmer (more crops).
3. Precipitation has increased recently.  Land usually flooded every 100 to 500 years.  Now we are flooding every 2 to 3 decades (each precipitation event has even more rain).
4. Summers:
1. Are hotter and drier.
2. Hurts cattle and humans with more frequent heat waves.
3. Dry seasons have less water, hurts crops.
4. Global Warming causes greater warming at the Polar Region opposed to the equator (this was recorded by GFDL).
1. models have predicted 100 years before melting.
5. The Northern Polar Ice Cap is expected to melt, but the water levels are not expected to rise significantly with this because water has already been displaced by ice.
6. The Southern Polar Ice Cap is not displacing water.  It is located on land shelves.  When this melts, the water levels are expected to rise 5-6 meters, mixing fresh water into salt water.  This will upset the global conveyor patterns of ocean currents.
1. This will displace 70 million people in China and Bangladesh.
2. Insurance Companies believe that $2 trillion of US coastline will be lost.  This could prove catastrophic to the economy.
7. Species displacement predicted:
1. Malarial mosquitoes have increased their range from 40 to 60% of world.  This would greatly increase disease.
2. Animals would move to higher, more favorable climates (disrupting entire ecosystems, pulling threads holding ecosystems together).
8. Increased heat/UV/Pollutants would decrease the immune system in humans and animals, increasing the frequency and amount of lethal diseases.
Image Location:  NOAA Climgraph: Educational Graphics on Global Climate

Global Concerns:

1. Skeptics argue that models aren't accurate.
1. They are not sure how oceans take extra CO₂ from the atmosphere, and water vapor is really the most important greenhouse gas that will increase temperatures.
2. The earth system is self-correcting, built-in mechanisms compensate for the changes in the atmosphere.
3. Increased CO₂ increases plant growth and make H₂O use more efficient.
4. Without putting CO₂ into the atmosphere, we would cool tremendously.
5. Increased sulfate aerosols (volcanic and fossil fuel emissions) actually reduce temperatures and offset the heating effects of carbon dioxide
2. Regulations:
1. 1979 - Geneva - scientists and policy makers meet for first time to discuss the problem of increasing greenhouse gases.
2. 1992 - Rio Accord:  Earth Summit objective:  stabilize greenhouse gases to prevent dangerous effects.  First agree to track the emissions of CO₂ .
3. 1995 - IPCC panel.  Scientists all over the world study increasing temperature effects and determine the 1.3 to 3.5 degree celsius increase:
1. Return to pre-1990 emissions.
2. U.S. producers produce an extra 22 million tons of CO₂.  U.S. is the largest anthropogenic source of CO₂.
3. China is second (will soon be first).
4. Kyoto Protocol:  Japan, December 1997.
1. All industrial nations pledge, 160 nations agreed to roll back to 5.2% below 1990 levels of all greenhouse gases.

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Resources:

National Geographic, May 1998, Unlocking the Climate Puzzle.

Kaufman, Donald G. and Franz, Celilia M., 1996, Biosphere 2000: Protecting our Global Environment, Kendall/Hunt Publishing Co., Debuque, IOWA
 
Scripps Institute of Oceaonography, l997, International Experiment in Indian Ocean to Study Role of Pollutants in Climate Change, on line

Quayle, Robert G. and Thomas, R. Karl (Eds.), l996, ( NOAA)  A Synopsis for Policymakers of Intergovernmental Panel on Climate Change, on line

Godfrey, Cahterine, l997, (NOAA)  Decadal-to-Centennial Climate Change: What We Know-What We Don't, on line
 
UNEP, Information Unit on Climate Change (IUCC), l993, Oceans and the Carbon Cycle, on line

Barron, Eric J., l995, Eos Vol.76, No. 18, May 2, l995, pp. 185, l89-l90, American Geophysical Union, Global Change Researchers Assess Projections of Climate Change, on line

The Lancet, Vol 351, October - December 1993, Health in Climate Change

Center for Diseae Control, teacher's site "EXCITE"  on line. 

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