Climate Change

A change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability over comparable time periods.

Source:

Climate Action Network International, "Climate Change Basics Glossary," Available Online at http://www.climatenetwork.org/climate-change-basics/climate-change-basics-glossary/?searchterm=glossary.  Retrieved October 27, 2008

Alternate Definition:

Climate change as referred to in the observational record of climate occurs because of internal changes within the climate system or in the interaction between its components, or because of changes in external forcing either for natural reasons or because of human activities. It is generally not possible clearly to make attribution between these causes. Projections of future climate change reported by IPCC generally consider only the influence on climate of anthropogenic increases in greenhouse gases and other human-related factors. (IPCC Usage)

Source:

Intergovernmental Panel on Climate Change, "Climate Change: A Glossary by the Intergovernmental Panel on Climate Change," Available Online at http://www.ipcc.ch/pdf/glossary/ipcc-glossary.pdf, Retrieved October 27, 2008