Global climate change Essay

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GLOBAL CLIMATE CHANGE The information contained in this report is designed to provide you clear, understandable information regarding the science and impacts of global climate change (what many people refer to as "global warming"). We provide information about greenhouse gases, their sources and atmospheric concentrations; global temperature data; the greenhouse effect; and projected impacts of climate change. The global climate - considered the average weather, usually over a 30-year time period - can be influenced by both natural forces and human activities. "Climate change" refers to any change in climate over time whether due to natural variability or as a result of human activity. Natural changes in climate result from processes internal to the climate system, such as the complex transfer of heat, moisture and momentum between the atmosphere and ocean. Natural changes can also stem from external "forcings" of climate, such as changes in the Sun's energy output or in the amount of volcanically-ejected gases and particles in the atmosphere. Climate change historically has occurred as a result of these natural forces, but is now occurring in part because of human activities. The greenhouse effect - which allows incoming solar radiation to pass through the Earth's atmosphere but prevents much of the outgoing infra-red radiation from escaping into outer space - is a natural process. The natural greenhouse effect has kept the Earth's average surface temperature approximately 33 degrees Celsius (roughly 60 degrees Fahrenheit) warmer than it would be were there no atmosphere. Natural greenhouse gases (GHGs) include water vapor, carbon dioxide (CO2), ozone (O3), and other trace gases. Without this natural greenhouse effect, life on Earth as we know it would not exist. Emissions of some of these greenhouse gases as a result of human activities over the past

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