JQ#30 1.What is a greenhouse gas? (Hint…think about what it feels like in a greenhouse.) 2.What gases found in our atmosphere are greenhouse gases? (Hint – they are in that 1% other category!) 3.How do greenhouse gases affect Earth?
Greenhouse Gas Simulation Infrared Radiation or HEAT people will: If you touch a H2, O2, or N2 – keep moving out to space If you touch a greenhouse gas - Methane, Ozone, CO2, or Water Vapor – let go and bounce back towards Earth After you pass the clouds, you may leave into space
Greenhouse Gas Simulation #1 Question #1: What role do greenhouse gases like carbon dioxide, ozone, methane, and water vapor play in the temperature of the Earths surface? Question #2: How does this affect human life on Earth? Question #3: Do all gases absorb heat?
Greenhouse Gas Simulation #2 In your notebook…. 4. Record or draw what you witnessed in the 2nd simulation 5.Explain the role of greenhouse gases on the surface temperature of Earth. 6.How do greenhouse gases affect human life? 7. What happens to the heat energy when the amount of greenhouse gases increases?
Review of Greenhouse Gases
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits infrared radiation, or heat energy. The main greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, fluorinated gases, and ozone.
The Greenhouse Effect The greenhouse effect is a process by which heat from a planets surface is absorbed by greenhouse gases in the atmosphere, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an increase in the average surface temperature above what it would be in the absence of those gases.
Carbon Dioxide (CO 2 ) Enters the atmosphere through: – Burning fossil fuels (coal, natural gas and oil) – Burning of solid waste – Burning trees and wood products – Certain chemical reactions (e.g., manufacture of cement). Carbon dioxide is removed from the atmosphere (or "sequestered") when it is absorbed by plants as part of the biological carbon cycle.
Water Vapor (H 2 O) Enters the atmosphere through: – Evaporation or transpiration in the water cycle Leaves the atmosphere through condensation and precipitation!
Methane (CH 4 ) Methane is emitted during: – The production and transport of coal, natural gas, and oil – Livestock and other agricultural practices – Decay of organic waste in landfills. – Decay of organic material in wetlands. (This is the largest natural source.)
Nitrous Oxide (N 2 O) Emitted during: – Agricultural and industrial activities – Burning of fossil fuels and solid waste
Fluorinated Gases They are synthetic, powerful greenhouse gases that are very potent but are made in small amounts – Hydrofluorocarbons (HFCs) - Used for refrigeration and air conditioners – Perfluorocarbons (PFCs) – Used as a solvent – Sulfur hexafluoride - Used in the electrical industry – Chlorofluorocarbons (CFCs, Freon), Hydrochlorofluorocarbons (HCFCs) and Halons – Used as a refrigerant, propellants, and solvents
Global Warming Potential Certain greenhouse gases (GHGs) are more effective at warming Earth ("thickening the blanket") than others.The two most important characteristics of a GHG in terms of climate impact are how well the gas absorbs energy (preventing it from immediately escaping to space), and how long the gas stays in the atmosphere. The Global Warming Potential (GWP) for a gas is a measure of the total energy that a gas absorbs over a particular period of time (usually 100 years), compared to carbon dioxide.  The larger the GWP, the more warming the gas causes. For example, methane's 100-year GWP is 21, which means that methane will cause 21 times as much warming as an equivalent mass of carbon dioxide over a 100-year time period.  Carbon dioxide (CO 2 ) has a GWP of 1 and serves as a baseline for other GWP values. CO 2 remains in the atmosphere for a very long time - changes in atmospheric CO 2 concentrations persist for thousands of years. Methane (CH 4 ) has a GWP more than 20 times higher than CO 2 for a 100-year time scale. CH 4 emitted today lasts for only about a decade in the atmosphere, on average.  However, on a pound- for-pound basis, CH 4 absorbs more energy than CO 2, making its GWP higher. Nitrous Oxide (N2O) has a GWP 300 times that of CO 2 for a 100-year timescale. N2O emitted today remains in the atmosphere for more than 100 years, on average.  Chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) are sometimes called high-GWP gases because, for a given amount of mass, they trap substantially more heat than CO 2.
Albedo How strongly something reflects light. – Clouds, ice, snow, and air pollutants have a high albedo. – Dark land cover, trees, oceans have a low albedo.