View source for Abrupt climate change

[[Category:Done 2016-04-30]] 
<onlyinclude>'''Abrupt climate change''' is a specific type of [[climate change]] that can occur naturally or possibly as a result of human activities. In abrupt climate change, the [[climate]] system changes to a new climate state rapidly, generally over a time scale which is much faster than the typical time scale of the [[climate forcing]] responsible for the change.</onlyinclude> Essentially, abrupt climate change is any sudden change in the climate system which results in a new climate state much more suddenly than is expected for whatever mechanism is responsible for the change.<ref name= nap>Committee on Abrupt Climate Change, National Research Council. (December 23, 2015). ''Abrupt Climate Change: Inevitable Surprises'' [Online]. Available: http://www.nap.edu/read/10136/chapter/3</ref> Abrupt climate change is often surprising ([[nonlinearity|non-linear]]), hard on living systems (which could include people), and almost impossible to reverse.<ref name = nap/> Many experts fear that [[anthropogenic]] [[climate change]] could become abrupt climate change, dramatically impacting people all over the world in bad ways.

Although [[external forcing]]s can result in abrupt climate change, not all abrupt climate changes are externally forced. Some of these changes may be unexpected, and occur as the result of some strong, rapidly changing forcing that pushes the climate system in a [[nonlinearity|nonlinear]] fashion.<ref>IPCC, 2012: Glossary of terms. 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 (IPCC). Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 555-564. </ref> Abrupt climate changes can impact a region, hemisphere, or even the entire globe.<ref name="RE1">NOAA. (December 23, 2015). ''Defining Abrupt Climate Change'' [Online]. Available: http://www.ncdc.noaa.gov/paleo/abrupt/story1.html</ref> One major concern with the climate change that is currently occurring as a result of human activities is that the changes that are occurring at a steady rate now could rapidly and suddenly change the climate system of the Earth. This case is concerning as there is not a good way to predict this sudden climate change, as well as the fact that adapting to some sudden change in the overall climate of a region would be extremely difficult.

==Types of Changes==
There are several different ways that a drastic, abrupt change in the climate could occur. From observations of paleoclimatic records, there are four major types of changes that if they were to occur, they would pose significant risks in terms of how well society would be able to adapt to said changes. Essentially, if human activities are pushing the climate towards some sort of abrupt change, it is the following changes that would pose the biggest threat to humanity:<ref>US Climate Change Science Program. (December 23, 2015). ''Abrupt Climate Change'' [Online]. Available: http://data.globalchange.gov/assets/71/4c/6665e91ddf094b0bb21bec42f03e/sap3-4-final-report-all.pdf</ref>
# Rapid changes in the amount of ice in [[glacier]]s and ice sheets. The melting of these ice packs would result in a in increase in sea level, potentially flooding or submerging coastal towns and cities. Additionally, the loss of these [[ice cap]]s and glaciers would change the [[albedo]] of the surface of the Earth, changing the amount of incoming [[solar radiation]] that is reflected and absorbed. This would further impact changes in the average [[global surface temperature|global temperature]].
# Widespread, long term changes to how water cycles across the Earth in the [[hydrologic cycle]]. Because [[water]] is incredibly important to life on Earth, significant changes in where fresh water is located and how it moves would significantly impact life.
# Abrupt change in the flow of warm salty water in the Atlantic Ocean. 
# Rapid release of [[methane]] - a [[greenhouse gas]] - trapped in permafrost into the [[atmosphere]], which would rapidly accelerate the global warming process.
Other possible changes include:<ref>IPCC. (December 23, 2015). ''Climate Change 2014 Synthesis Report'' [Online]. Available: https://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_FINAL_full.pdf#89</ref>
# [[Ocean acidification]]
# Changes in the composition of [[biome]]s
# Changes in the levels of soil [[carbon]]

==Current Climate Change==
One common notion that exists surrounding climate change is that climate is always changing, so any change happening currently is no different than natural climate shifts over time. However, the changes occurring in the climate presently are more accelerated than previous climate change events. This comparatively rapid increase in global surface temperature and changes in weather patterns can be seen as abrupt in comparison to historical events. For more information on how the climate is changing rapidly as a result of human effects, please see the IPCC's summary [http://www.climatechange2013.org/images/report/WG1AR5_FAQbrochure_FINAL.pdf#14 here] or watch the video from 'This is not cool with Peter Sinclair' by Yale Climate Connections:

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==References==
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