Greenhouse Effect: The heating of the surface of the earth due to the presence of an atmosphere containing gases that absorb and emit infrared radiation The Earth receives energy from the Sun in the form of visible light and nearby wavelengths Close to 50% of the sun’s energy is absorbed at the earth’s surface The other sunlight (solar radiation) is reradiated back into the atmosphere as longer-wave energy (heat) Greenhouse gases absorb this heat and trap it in the lower atmosphere causing the earth’s temperature to rise

The Earth’s most abundant greenhouse gases are (by contribution to their effect):  Water Vapor (H2O) contributes %  Carbon Dioxide (CO2) contributes 9-26%  Methane (CH4) contributes 3-7%  Ozone (O3) contributes 3-7%

The largest Anthropogenic (human-produced) greenhouse gas is Carbon Dioxide, which is said to contribute the most to additional absorption and emission of thermal infrared The rise is CO2 levels is mostly contributed to the burning of fossil fuels and land-use change

Most significant potential consequences of global warming: Glaciers will melt more and more Positive feedback loops: Glaciers are more reflective than the earth, so when they melt, more of the sun’s heat will be absorbed. Also, as the atmosphere is warmed, the amount of water vapor increases Sea levels will rise Wild land fires Affects on wildlife – polar bears

Critics of Global Warming: Decreasing the level of CO2 harms our industry’s ability to produce and could really hurt our economy Previous weather fluctuations (Medieval Warm Period and the Little Ice Age), is not proven to be anthropogenic It is real, but not a crisis. More people die each year from excess cold than from excess heat Kyoto Protocol: Exemption for developing countries, and China and India’s gross national CO2 emissions now exceed the US