What is climate change?

The United Nations Intergovernmental Panel on Climate Change defines climate change as a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.1 (IPCC, 2012 : Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation)

What is the cause of climate change?

Climate change is primarily caused by the accumulation of greenhouse gases in the atmosphere, trapping the sun’s heat commonly known as the greenhouse effect.  

The “greenhouse effect”, a natural phenomenon which makes the Earth a liveable planet, is the warming that happens when certain gases in Earth’s atmosphere trap heat. These gases let in sunlight but keep heat from escaping, like the glass walls of a greenhouse that is why it is called green house effect.

First, sunlight shines onto the Earth’s surface, where it is absorbed and then radiates back into the atmosphere as heat. In the atmosphere, “greenhouse” gases trap some of this heat, and the rest escapes into space. The more greenhouse gases are in the atmosphere, the more heat gets trapped.

Through the burning of fossil fuels and the emission of other GHGs, humans are continuously enhancing the greenhouse effect, further warming the Earth.

Examples of these gases are:
•    Water vapor
•    Carbon dioxide
•    Methane
•    Nitrous oxide
•    Human-made gases generated during industrial processes such as sulfur hexafluoride, hydroflourocarbons and perfluorocarbons

There are two main approaches to address climate change.

Adaptation: In human systems, the process of adjustment to actual or expected climate and its effects, in order to moderate harm or exploit beneficial opportunities. In natural systems, the process of adjustment to actual climate and its effects; human intervention may facilitate adjustment to expected climate.2 (IPCC, 2012: Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 3-21.)

Mitigation: Technological change and changes in activities that reduce resource inputs and emissions per unit of output and implementing policies to reduce greenhouse gas emissions and enhance sinks.3 (Verbruggen, A., W. Moomaw, J. Nyboer, 2011: Annex I: Glossary, Acronyms, Chemical Symbols and Pre? xes. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation [O. Edenhofer, R. PichsMadruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA)




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