Climate system Q&A: What are the ‘tipping points’?

A tipping point is the point at which small changes in the Earth’s climate system become significant enough to cause a larger, more critical change that can be abrupt, irreversible, and lead to cascading effects.

If tipping points — sometimes called tipping elements — are crossed, they are likely to have severe impacts on human society. They are large-scale components of the Earth system characterised by “a threshold behaviour”, such as dieback of the Amazon rainforest; collapse of the Greenland ice sheet or the Gulf Stream slowing down.

What happens when climate tipping points are about to break through?

When relevant aspects of the climate approach a threshold, these components can be tipped into a different state by what are known as “small external perturbations”. In short, they become so vulnerable due to global heating, it doesn’t take much to finally push them in the wrong direction.

To compare them with the human body, tipping points could be described as organs which drastically alter or stop functioning normally if certain requirements, such as oxygen supply, are not met.

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Alternatively, tipping points can also be explained by a see-saw and a rolling ball. Before the pivot, you have to keep pushing the ball yourself up the incline. But after the pivot the ball rolls away quickly without any further pushing.

[ Climate at risk of crossing critical ‘tipping points’ sooner than expected — study ]

[ Risk of passing multiple climate tipping points escalates ‘above 1.5 degrees of global warming’  ]

When did tipping points begin to feature in climate science?

The concept of tipping points was introduced by the UN Intergovernmental Panel on Climate Change (IPCC) 20 years ago, but then it was thought they would only occur if global warming reached 5 degrees above pre-industrial levels. Recent IPCC assessments, however, suggest tipping points could be reached between 1 degree and 2 degrees of warming.

On top of that, the threshold behaviour is often based on self-reinforcing processes which, once tipped, can continue without further forcing. It is thus possible that a component of the Earth system remains “tipped”, even if the background climate falls back below the threshold or, for instance, carbon dioxide in the atmosphere is significantly reduced.

Does this mean tipping points will quickly lead to an unlivable planet?

There will never be a point where all is lost, according to climate scientists Johan Rockström and Owen Gaffney. If the world crosses tipping points, it may still be able to control the rate of change by acting decisively.

But the longer we wait, the more turbulence and turmoil left for generations to come, they explained in their book Breaking Boundaries published, last year.

Are there positive climate tipping points?

Scientists are increasingly identifying positive tipping points that are sources of hope. They can be found in a range of areas — from agriculture and ecosystem regeneration to politics and public opinion. Some are already in progress; others are yet to be triggered. Understanding these areas and working to identify opportunities could facilitate the activation of such tipping points with the potential to combine into cascades of positive change.

“Just as tipping points are part of the greatest threat we face — the same logic may also provide the solution. At the University of Exeter [UE], we have identified a variety of positive tipping points in human societies that can propel rapid decarbonisation. This concept could unlock the stalemate — the sense that there’s nothing we can do about climate change,” explains Prof Tim Lenton, director of the Global Systems Institute at UE.