Climate threshold

A climate threshold is a critical limit where a climate system responds drastically when exposed to an external forcing, resulting in the system changing into a different stable state.[1] An analogy can be made to tipping a wine glass - if it tips too far from its standing state it will fall and spill the wine, leaving the glass in a stable state on its side. Thus a climate threshold is also referred to as a "tipping point". Climate threholds are an example of how the climate behaves in a non-linear way, often as a result of positive climate feedback mechanisms.

The climate tends to respond to changes in a gradual way until it reaches a threshold. Once past this threshold, what is known as abrupt climate change begins to occur, where the climate's response to a forcing is much larger than the change in that forcing.[2] Thresholds are important to study in order to test how well climate models can simulate their effects.

For example, a threshold exists with the increased amounts of freshwater flowing into the ocean from melting ice. This freshwater is a potential forcing for abrupt climate changes; both sea levels and ocean circulations could change drastically.[3]

References

  1. 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.
  2. IPCC. (Accessed July 4, 2016). Thresholds and Abrupt Climate Change [Online], Available: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-thresholds-and.html
  3. IPCC. (Accessed July 4, 2016). Rapid West Antarctic and/or Greenland Ice Sheet Collapse and Meridional Overturning Circulation Changes [Online], Available: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-7-2-2.html

Authors and Editors

Jordan Hanania, Jason Donev
Last updated: September 17, 2016
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