Global Warming

Rising Levels of Greenhouse Gases Carbon dioxide accounts for 49% of the human-caused input of greenhouse gases. Major Sources of CO 2 input: Fossil-fuel burning80% Deforestation20% CO 2 remains in the atmosphere for about 500 years once it gets there. Industrial countries account for about 76% of the annual emmissions

Chlorofluorocarbons (CFC’s) account for 14% of the human input of greenhouse gases. CFC’s generally have 10,000 to 20,000 times the impact on global warming per molecule when compared to CO 2 CFC’s stay in the atmosphere 65 to 111 years and also contribute to ozone depletion. Major Sources: Leaking air conditioners and refrigerators Evaporation of industrial solvents Production of plastic foams Propellant in aerosol cans

Methane (CH 4 ) is responsible for 18% of the human input of greenhouse gases. It is produced by bacteria that decompose organic matter in anaerobic environments. Natural sources produce about 1/3 of the methane in the atmosphere and include: Emissions from water logged soils, bogs, marshes, and rice paddies The gut of termites The gut of livestock Coal seams Other sources include landfills, natural gas wells, pipelines, storage tanks, furnaces, etc. Methane stays about 7 to 10 years in the atmosphere and is about 25 times more effective in warming the atmosphere when compared to CO 2

Nitrous Oxide (N 2 O) is responsible for 6% of the human input of greenhouse gases. N 2 O is released from the breakdown of nitrogen fertilizers in soil, livestock wastes, and nitrate contaminated water. N 2 O is also created when biomass fuels are burned. It stays in the atmosphere for about 150 years and is 230 times more potent than CO 2 as a greenhouse gas.

Contributing Countries United States18% European Countries13% Soviet Union12% Brazil11% China 7% India 4% Japan 4% Canada 2% Mexico 1.4%

Greenhouse Gas Emission Effects While there is no doubt greenhouse gases are being emitted into the atmosphere at increasing rates, the effect of these emissions is a subject for debate First, the effect on global temperature is widely debated. Reliable temperature measurements are only available from Since that time the temperature has only risen slightly or by some estimates has even fallen. Since this amount is so small the normal short-term temperature swings have not been exceeded.

Global Temperature Measurements

Sea Level Trends

Precipitation

SO….What will happen? Current models project the earth’s temperature will rise o C over the next 50 years. There are many uncertainties in this modeling. Modelers believe their models are accurate to within a factor of two. This means the actual warming may be between 0.7 o C and 11 o C. That is 10 to 100 times faster than has occurred during the last 10,000 years. A rise of 1.5 o C would make the earth warmer than it has been in the last 100,000 years.

Local Effects It is very difficult to model the effect global warming would have on any one particular area, but many estimates have been made. It is reasonable to suppose that sea levels would rise and precipitation patterns would change. This would obviously cause many problems: flooding, food production problems, etc.

What can be done? Input approaches Ban production of CFC’s Cut fossil fuel use Improve energy efficiency Shift to alternative energy sources Promote energy efficiency in lesser developed countries Increase use of nuclear power Tax gasoline and emissions Reduce use of coal Capture methane released from landfills\Reduce beef production Stop Deforestation Slow population growth

Output Approaches Develop methods to remove CO 2 from stack gases. Plant trees Recycle CO 2 in industrial processes Stimulate removal of CO 2 from atmosphere by photosynthesis Individual Actions Be aware of your CO 2 emissions and reduce them Reduce your use and unnecessary waste of energy Don’t use electricity to heat space or water Make your home energy efficient Use alternative energy sources Use natural gas where you can in place of electricity Plant trees Reduce, Reuse, Recycle Buy reusable products Support appropriate legislation