Tipping point (climatology)

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Rate of Greenland ice sheet melt

A climate tipping point is a point when a global climate changes from one given stable state to another stable state, much as when stemware, after being tilted from its base, finally tips over. After the tipping point has been passed, a transition to a new state occurs. The tipping event may be irreversible, much like the spilling out of the wine originally contained in the glass: standing up the glass will not put the wine back.


The IPCC AR5 report stated that precise levels of climate change sufficient to trigger a tipping point, defined as a threshold for abrupt and irreversible change, remain uncertain, and that the risk associated with crossing multiple tipping points increases with rising temperature.[1]

In the context of climate change, an "adaptation tipping point" has been defined as "the threshold value or specific boundary condition where ecological, technical, economic, spatial or socially acceptable limits are exceeded."[2]


Global warming proceeds because of changes to the composition of gases in the Earth's atmosphere and Oceans by the emission of greenhouse gases such as carbon dioxide and methane. As warming proceeds, it brings about changes to the natural environment which may result in other changes. For example, warming may begin to melt the Greenland ice sheet and/or West Antarctic Ice Sheet. At some level of temperature rise, the melt of the entire ice sheet will become inevitable; but the ice sheet itself may persist for millennia[citation needed]. A tipping point may be passed without any immediately obvious consequences, nor any acceleration of the warming process. Carbon dioxide as of May 2012 made up 396.18 ppm of Earth's atmosphere[3] and as of 2016 makes up 403.3 ppm of Earth's atmosphere[4]. Monitoring stations in the Arctic spring 2012 measuring more than 400 ppm of the heat-trapping gas in the atmosphere.[5] James E. Hansen said that this tipping point had already been reached in April 2008 when the CO2 level was 385 ppm. (Hansen states 350 ppm as the upper limit.) "Further global warming of 1°C defines a critical threshold. Beyond that we will likely see changes that make Earth a different planet than the one we know."[6] He has further suggested potential projections of runaway climate change on Earth, in his book Storms of My Grandchildren.

Some scientists and other specialists sometimes express concern about global warming and irreversible tipping points, and use metaphors such as "the door is closing"[7] and warn of global food[citation needed] and water shortages[citation needed], hundreds of millions of people being displaced by rising sea levels, famine, unhealthy and unlivable conditions, and storms becoming ever more frequent and severe worldwide.[8]

Others have tried systematically to short-list large scale components of the Earth system that may be subject to tipping points, defining tipping points as a variety of phenomena, including the onset of positive feedback, hysteresis effects, and the possible effect of statistical noise at critical points.[9]

Arctic sea ice[edit]

In 2013, a study noted that there is an ongoing debate as to whether Arctic sea ice has already passed a "tipping point", or if it is likely in the future. They pointed out, "Several recent studies argue that the loss of summer sea ice does not involve an irreversible bifurcation, because it is highly reversible in models". The study identified in 2007 abrupt transition in seasonal variability which persisted since then, and made a distinction between bifurcation and non-bifurcation ‘tipping point'.[10]


Tipping elements as highlighted by Lenton et al. (2008)[9]

Lenton et al. (2008) highlights a number of tipping elements,[9] including:

See also[edit]


  1. ^ IPCC AR5 WGII (2014). "Climate change 2014, Impacts, Adaptation and Vulnerability" (PDF). Archived from the original (PDF) on 2015-05-14.
  2. ^ Ahmed, Farhana; Khan, M Shah Alam; Warner, Jeroen; Moors, Eddy; Terwisscha Van Scheltinga, Catharien (2018-06-28). "Integrated Adaptation Tipping Points (IATPs) for urban flood resilience". Environment and Urbanization. 30 (2): 575–596. doi:10.1177/0956247818776510. ISSN 0956-2478.
  3. ^ "NOAA ESRL DATA". NOAA. 7 May 2012. Retrieved 9 May 2012.
  4. ^ "Worrying Rise". WMO. 31 Oct 2017. Retrieved 31 Oct 2017.
  5. ^ Borenstein, Seth (31 May 2012). "Scientists: Carbon dioxide at highest level in 800,000 years". USA Today. Associated Press.
  6. ^ Earth in crisis, warns NASA's top climate scientist Archived 2008-04-12 at the Wayback Machine PhysOrg.com, April 07, 2008 . Accessed August 2008.
  7. ^ Luderer, Gunnar; Pietzcker, Robert C; Bertram, Christoph; Kriegler, Elmar; Meinshausen, Malte; Edenhofer, Ottmar (1 September 2013). "Economic mitigation challenges: how further delay closes the door for achieving climate targets". Environmental Research Letters. 8 (3): 034033. Bibcode:2013ERL.....8c4033L. doi:10.1088/1748-9326/8/3/034033.
  8. ^ Saunders, Marshall (22 April 2012). "Earth to mankind". The Gainesville Sun. Retrieved 9 May 2012.
  9. ^ a b c Lenton, T. M.; Held, H.; Kriegler, E.; Hall, J. W.; Lucht, W.; Rahmstorf, S.; Schellnhuber, H. J. (2008). "Inaugural Article: Tipping elements in the Earth's climate system". Proceedings of the National Academy of Sciences. 105 (6): 1786–1793. Bibcode:2008PNAS..105.1786L. doi:10.1073/pnas.0705414105. PMC 2538841. PMID 18258748.
  10. ^ Valerie N. Livina, Timothy M. Lenton (2013). "A recent tipping point in the Arctic sea-ice cover: abrupt and persistent increase in the seasonal cycle since 2007". The Cryosphere. 7 (1): 275–286. arXiv:1204.5445. Bibcode:2013TCry....7..275L. doi:10.5194/tc-7-275-2013.CS1 maint: Uses authors parameter (link)
  11. ^ Ian Sample (11 August 2005). "Warming hits 'tipping point'". London: The Guardian. Retrieved 21 September 2009.

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