Climate change refers to any significant change in measures of climate (such as temperature, precipitation or wind) lasting for an extended period (decades or longer). As through much of its history, the Earth's climate is changing. Right now it is getting warmer. Most of the warming in recent decades is very likely the result of human activities (IPCC, 2007). The National Oceanic and Atmospheric Administration’s (NOAA) State of the Climate Report and the National Aeronautics and Space Administration’s (NASA) Surface Temperature Analysis indicate the average temperature of the Earth’s surface has increased by about 1.2 to 1.4ºF since 1900. Other aspects of the climate are also changing such as precipitation patterns and storminess.
During the past century humans have substantially added to the amount of greenhouse gases in the atmosphere by burning fossil fuels such as coal, natural gas, oil and gasoline to power our cars, factories, utilities and appliances. The added gases — primarily carbon dioxide and methane — are enhancing the natural greenhouse effect, and likely contributing to an increase in global average temperature and related climate changes.