Climate change

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 over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) and, more recently, human activities.

In recent usage, especially in the context of environmental policy, the term "climate change" often refers to changes in modern climate which according to the IPCC are 90-95% likely to have been in part caused by human action. Consequently the term anthropogenic climate change is frequently adopted; this phenomenon is also referred to in the mainstream media 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] In the 1970s timeframe, this term was more often associated with the phenomena of global cooling.

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.

Contents

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• 1 Climate change factors
  • 1.1 Variations within the Earth's climate
    • 1.1.1 Glaciation
    • 1.1.2 Ocean variability
    • 1.1.3 The memory of climate
  • 1.2 Non-climate factors driving climate change
    • 1.2.1 Greenhouse gases
    • 1.2.2 Plate tectonics
    • 1.2.3 Solar variation
    • 1.2.4 Orbital variations
    • 1.2.5 Volcanism
  • 1.3 Human influences on climate change
    • 1.3.1 Fossil fuels
    • 1.3.2 Aerosols
    • 1.3.3 Cement manufacture
    • 1.3.4 Land use
    • 1.3.5 Livestock
• 2 Interplay of factors
• 3 Monitoring the current status of climate
• 4 Evidence for climatic change
  • 4.1 Pollen analysis
  • 4.2 Beetles
  • 4.3 Glacial geology
  • 4.4 Historical records
• 5 Examples of climate change
• 6 Climate change and economics
• 7 Climate change in popular culture
• 8 Climate Change and biodiversity
• 9 See also
• 10 References
• 11 Notes
• 12 External links
  • 12.1 Public administrations and organizations
  • 12.2 Other links

http://en.wikipedia.org/wiki/Climate_change