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). Climate change may result from:

• Natural factors, such as changes in the sun's intensity or slow changes in the earth's orbit around the sun
• Natural processes within the climate system (e.g. changes in ocean circulation)
• Human activities that change the atmosphere's composition (e.g., through burning fossil fuels) and the land surface (e.g., deforestation, reforestation, urbanization, desertification, etc.)