1. The Greenhouse effect Is a natural process necessary for sustaining life on earth Is a natural process necessary for sustaining life on earth Is produced by the sun’s energy and earth’s atmosphere Is produced by the sun’s energy and earth’s atmosphere

2. How it works Energy in the form of solar radiation is emitted toward earth. Energy in the form of solar radiation is emitted toward earth. 26% is reflected 26% is reflected 19% absorbed 19% absorbed

3. 55% reaches earth’s surface. 55% reaches earth’s surface. 4% of that is reflected to space and 4% of that is reflected to space and the remaining 51% is absorbed by earth’s surface and re-emitted as long wave infrared radiation. the remaining 51% is absorbed by earth’s surface and re-emitted as long wave infrared radiation.

4. Greenhouse gases trap this radiation, warm the atmosphere and emits the heat back to earth where a cycle begins. Greenhouse gases trap this radiation, warm the atmosphere and emits the heat back to earth where a cycle begins.

5. Main Greenhouse Gases CO2 has had a 33% increase in concentration in last 200 years. CO2 has had a 33% increase in concentration in last 200 years. Comes from burning fossil fuels for industry, transportation, heat, cooking, and electricity generation. Comes from burning fossil fuels for industry, transportation, heat, cooking, and electricity generation. Also released Also released from deforestation

6. Methane has risen 151% since 1750. Methane has risen 151% since 1750. Released by large herds of cattle, tapping into fossil fuel deposits, dumping organic matter into landfills, and crops such as rice. Released by large herds of cattle, tapping into fossil fuel deposits, dumping organic matter into landfills, and crops such as rice. Humans are cause of half of methane released Humans are cause of half of methane released

7. Ozone serves a dual purpose. Ozone serves a dual purpose.  In lower stratosphere it keeps earth cooler by absorbing radiation before it reaches earth.  In troposphere it is building up and then trapping heat. It also causes health problems. It has decreased in stratosphere because of CFCs but increased 36% in troposphere since 1750. It has decreased in stratosphere because of CFCs but increased 36% in troposphere since 1750.

8. Halocarbon gases are man made. Halocarbon gases are man made. They include chlorofluorocarbons (CFCs) which deplete the ozone layer. They include chlorofluorocarbons (CFCs) which deplete the ozone layer. Emissions have almost stopped now due to the Montreal Protocol. Emissions have almost stopped now due to the Montreal Protocol.

9. Montreal Protocol Was called in 1987 because of health concerns and fears of global warming. Was called in 1987 because of health concerns and fears of global warming. Signed by 180 nations, demanded CFC production dropped by 50%. Several amendments now have dropped it to 95%. Signed by 180 nations, demanded CFC production dropped by 50%. Several amendments now have dropped it to 95%.

10. Future of the Climate Scientists all agree earth’s climate is warming due to increased greenhouse gas concentrations. They do not know how it will continue, however. Scientists all agree earth’s climate is warming due to increased greenhouse gas concentrations. They do not know how it will continue, however. Some believe it will all work itself out. Some believe it will all work itself out. World Health Organization says immediate and long term health benefits will come from reducing gas emissions. World Health Organization says immediate and long term health benefits will come from reducing gas emissions.

11. Reducing Greenhouse Gases We can build more efficient machines. Automobiles are highly inefficient and transportation is second highest contributor to gas emissions in U.S. We can build more efficient machines. Automobiles are highly inefficient and transportation is second highest contributor to gas emissions in U.S. Planting trees. An average tree intakes 13 pounds of carbon and carbon dioxide a year and maintains it for the life of the tree. Planting trees. An average tree intakes 13 pounds of carbon and carbon dioxide a year and maintains it for the life of the tree.

12. So the greenhouse effect is necessary for maintaining life on earth. So the greenhouse effect is necessary for maintaining life on earth. Our climate is changing and we do not know how it will continue. Our climate is changing and we do not know how it will continue. Greenhouse gas concentrations are rising and need to be slowed as much as possible. Greenhouse gas concentrations are rising and need to be slowed as much as possible. Estimates point to a 1-3 degrees Celsius rise in earth’s average temperature over the next century. Estimates point to a 1-3 degrees Celsius rise in earth’s average temperature over the next century.