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Note: The linked article below seems to be a reasonably good resource for anyone who is interested in learning about climate change. MJ Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the variability or average state of the atmosphere—or average weather—over time scales ranging from decades to millions of years. These changes may come from processes internal to the Earth, be driven by external forces (e.g. variations in sunlight intensity) or, most recently, be caused by human activities.
In recent usage, especially in the context of environmental policy, the term "climate change" often refers only to the ongoing changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations.[1]
For information on temperature measurements over various periods, and the data sources available, see temperature record. For attribution of climate change over the past century, see attribution of recent climate change. Climate change factorsClimate changes reflect variations within the Earth's environment, natural processes going on around it, and the impact of human activity. The external factors which can shape climate are often called climate forcings and include such processes as variations in solar radiation, the Earth's orbit, and greenhouse gas concentrations. Variations within the Earth's climate Weather, in and of itself, is a chaotic non-linear dynamical system, but in many cases, it is observed that the climate (i.e., the average state of weather) is fairly stable and predictable. This includes the average temperature, amount of precipitation, days of sunlight, and many other variables that might be measured at any given site. However, there are also changes within the Earth's environment that can affect the climate.
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