1.4 Tipping points in ocean and atmosphere circulations

Sina Loriani, Yevgeny Aksenov, Henk Dijkstra, Matt England, Alexey Fedorov, Gabriele Messori, Francesco Pausata, JB Sallée, Bablu Sinha, Steven Sherwood, Thejna Tharammal, David I. Armstrong McKay, Govindasamy Bala, Andreas Born, Sybren Drijfhout, Laura Jackson, Kai Kornhuber, Cristiano M. Chiessi, Stefanie Rynders, Didier Swingedouw

Key Messages

  • There is evidence for tipping points in the overturning circulations in the Atlantic and the Southern ocean, as well as for the West African monsoon.
  • Short observational records, potential model biases towards stability, and limited resolution of various important feedback processes in models leave uncertainties, making an assessment of potential tipping difficult.


  • Prevent destabilisation of ocean and atmosphere circulations by urgent and ambitious reduction of greenhouse gas emissions and other pressures such as air pollution.
  • Fill knowledge gaps and improve models to constrain projected impacts for the next decades and beyond. Reduce uncertainties, for example related to the resolution of small-scale processes and interaction of different systems.
  • Invest in observations and palaeo reconstructions to detect early warning signs of tipping dynamics, and foster data sharing and international collaboration.


This chapter assesses scientific evidence for tipping points across circulations in the ocean and atmosphere. The warming of oceans, modified wind patterns and increasing freshwater influx from melting ice hold the potential to disrupt established circulation patterns. We find evidence for tipping points in the Atlantic Meridional Overturning Circulation (AMOC), the North Atlantic Subpolar Gyre (SPG), and the Antarctic Overturning Circulation, which may collapse under warmer and ‘fresher’ (i.e. less salty) conditions. 

A slowdown or collapse of these oceanic circulations would have far-reaching consequences for the rest of the climate system, such as shifts in the monsoons. There is evidence that this has happened in the past, having led to vastly different states of the Sahara following abrupt changes in the West African monsoon, which we also classify as a tipping system. Evidence about tipping of the monsoons over South America and Asia is limited, however large-scale deforestation or air pollution are considered as potential sources of destabilisation. Although theoretically possible, there is little indication for tipping points in tropical clouds or mid-latitude atmospheric circulations. Similarly, tipping towards a more extreme or persistent El Niño Southern Oscillation (ENSO) state is not sufficiently supported by models and observations. 

While the thresholds for many of these systems are uncertain, tipping could be devastating for many millions of people. Stabilising climate (along with minimising other pressures, like aerosol pollution and ecosystem degradation) is critical for reducing the likelihood of reaching tipping points in the ocean-atmosphere system.

The scientific content of this chapter is based on the following manuscript: Loriani et al., Tipping points in ocean and atmosphere circulations. Earth System Dynamics (submitted)

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